A coating or film applied to a surface to prevent or reduce its adhesion to another material. See release agent.


(a)The decomposition and volatilization of solid material. (b)In printing, intensely focused laser energy is used to impose a digital image onto the printing plate surface by ablating (evaporating away) a thin surface film (the ablation mask) to the appropriate pattern. In effect it creates an exceptionally thin photonegative attached directly to the printing plate material.


Surface damage caused by the rubbing of a part against another part or package surface. The wearing away of a material’s surface by friction.

abrasion resistance

The ability of a surface to withstand the effects of repeated rubbing, scuffing and scratching. Also referred to as scuff or rub resistance. The Sutherland ink rub tester is an instrument commonly used to evaluate a printing ink’s resistance to abrasion.


See acrylonitrile-butadiene-styrene.


The material property that causes a material to take up liquids with which it is in contact.


A material that will absorb liquids or gases into itself. An important packaging material category are those that absorb undesirable gases such as water vapor and oxygen. Oxygen scavengers, mostly based on finely divided iron, can be incorporated into packaging for use with oxygen-sensitive products. The absorbent chemical can be placed in a separate packet or sachet, or may be incorporated into some part of the packaging material itself. Moisture or water vapor absorbers or desiccants are used to remove or control the moisture or humidity level in a package. The majority of these are based on silica gels. Other systems are available for gases such as ethylene oxide, which is related to the ripening of certain fruits.


In automated packaging operations, a device, table, or type of conveyor designed to permit the gathering of materials, packages or objects. Accumulators should not be confused with buffers. The definition of buffer is to shield or cushion an upstream machine from a downstream machine that stops (via conveyor length or off-loading areas such as tables or conveyors where the inputs can gather). The two definitions are not interchangeable. See also accumulation.


Translucent to opaque resins produced by polymerization of formaldehyde and characterized by a high melting point, high strength and stiffness, and solvent resistance.


  1. a) In its chemical sense, acetate describes any chemical structure having an acetate functional group in its molecule. Acetate is often used as a generic description of any one of a family of plastic materials (for example cellulose acetate) or to one of a family of solvents, (for example, n propyl acetate). (b) In graphic arts the term “acetate” is occasionally used to describe film or sheet key-line overlays even though poly(ethylene terephthalate) (Mylar) has replaced cellulose acetate materials in most current applications.


A very active solvent used mainly in gravure inks. The fastest drying solvent in the ketone family.


Without color, a black-and-white image.


Trade name for a polychlorotrifluoroethylene (PCTFE) polymer. The polymer has outstanding moisture and excellent oxygen barrier properties, as well as being clear, rigid, and relatively easy to thermoform. Its main packaging application

is for pharmaceutical blister packages. Economics limits its use in other fields.


A general chemical term for thermoplastic materials made by polymerization of monomeric esters of acrylic acids. Acrylic plastics have crystal clarity, good surface hardness, good mechanical and chemical stability, and exceptional weatherability. Their cost prevents wide use in the packaging industry as molded parts or films. Acrylic resins are used extensively in adhesive formulations, particularly pressure- sensitive variations. Acrylic resins also are used in some printing ink formulations, particularly those that will experience outdoor exposure.


A monomer with the structure (CH = CHCN). Acrylonitrile polymer is rigid and can be impact modified with butadiene. Its copolymers have good gas barrier, chemical resistance, and are thermoformable.

acrylonitrile-butadiene-styrene (ABS)

Any of a family of thermoplastics based on acrylonitrile, butadiene, and styrene. The standard grades are rigid, hard, and tough, and possess good impact strength, heat resistance, low-temperature properties, and chemical resistance. ABS has had some limited application for thermoformed parts and film. ABS is sometimes used for large industrial and military shipping containers.

active packaging

Packaging that acts to help preserve products such as food because of substances like an antioxidant or a desiccant incorporated into the packaging material.


Materials such as plasticizers, preservatives, slip agents, antistatic agents, processing aids, and others, added to a base material in order to achieve a specific result. The term is broadly applied to any material added in small amounts to formulated products such as inks, plastics, papers, adhesives, and so on.

additive synthesis

The combining or adding together of different light wave- lengths to produce another color. Additive synthesis usually refers to the combining of red, green, and blue wavelengths since these are the only ones detected by the human eye. Red light plus blue light is seen as magenta, red light plus green light is seen as yellow, and blue light plus green light is seen as cyan. When all three wavelengths are mixed in about equal proportions, the human eye sees white. See also subtractive synthesis.


To stick together. To cause two surfaces to be held together by adhesion, for example, ink to stock.


The surface or material to which an adhesive has been applied. One of the two surfaces to be joined by an adhesive.


The attachment of one material to another primarily by molecular attraction. See also adhesion, mechanical and adhesion, specific.

adhesion, mechanical

A theory of adhesion that proposes that bonds are formed when liquid adhesive flows into irregularities and cavities in the material surface. When the adhesive solidifies, it becomes trapped and can no longer be removed.

adhesion promoter

A coating applied to the substrate that improves the bond of a material being attached to it. See primer.

adhesion, specific

A theory of adhesion that proposes that adhesive bonds are formed when polar molecules of the adhesive and substrate are brought into close enough proximity that they form a bond by mutual attraction of opposite polarities.

adhesion, ultimate

In most adhesive applications, final bond strength measured at some time after application is greater than initial bond strength as measured immediately after application. Ultimate bond strength is the strength of a bond at its maximum cured or matured state.


A substance that can be used to join two surfaces. A typical adhesive is a liquid capable of forming molecular attractions to the substrates (wetting), and then solidifying by evaporation of volatiles, cooling, or chemical reaction. See also adhesion, specific and adhesion, mechanical.

aging resistance

The resistance to deterioration and change by oxygen and ozone in the air, heat and light, or an internal chemical action. Stability over time. Related to shelf life.

air knife, air knife coater

A process where an excess amount of coating is applied by some means and the excess removed and final metering carried out by a sharp directed stream of high velocity air from a slot nozzle.

air entrapment, air entrainment

Air bubbles mixed in with inks, adhesives, coatings and other fluid materials.

air gap

The distance from the die lips of a polymer-melt extruder and the chill roll.


The positioning of mechanical components, stations, machines or material flow in relation to other mechanical components, stations, or machines in order to have an accurate material flow, correct positioning, or correct register.


Chemical agent having a pH value higher than 7 where pH of 7 is neutral, up to 14 indicates degree of alkalinity, and down to 1 indicates degree of acidity. Also referred to as a caustic or a base.

alkalinity, alkali activity

The degree of concentration of free hydroxyl ions (OH) capable of forming an alkali. On the pH scale a solution with pH higher than 7.

alkali-resistance, alkali resistant

The ability to withstand the action of alkaline materials and chemicals.

adhesive, thermoplastic

A synthetic adhesive requiring controlled heat to activate for application. Requires minimal holding time to obtain adhesive bond. See adhesive, hot melt.

adhesive, thermosetting

An adhesive that polymerizes and hardens and in this state it can no longer be melted. The polymerization reaction can be initiated by mixing two reactive components (as in two-part epoxy), by adding a catalyst, by heat, by UV radiation or by electron beam.

adhesive, two component, adhesive, two part

An adhesive system that requires the mixing of two reactive components. A two part epoxy is an example of such an adhesive. In some instances the second material is a catalyst and added only in very small amounts. In both instances, the mixing of the components starts an irreversible chemical reaction (polymerization). Two component adhesives have a limited pot life.

adhesive, waterborne

An adhesive that is either dissolved in water (for example a starch) or suspended in a water-based emulsion (for example a poly(vinyl acetate emulsion).

adhesive, waterproof

An adhesive that is not significantly affected by immersion in water over extended time periods.

adhesive, water-resistant

An adhesive that maintains reasonable bond quality after immersion in water for short periods of time as compared to a waterproof adhesive that would not be affected by water for extended periods of time.


Adhesiveness is, the ability of a material to adhere to other surfaces.


The material on whose surface adsorption takes place.


Attraction of a substance to a surface resulting from the attraction of molecules of the two substances, for example, the condensation or adhesion of gases, liquids, or dissolved substances on the surface of solids. The phenomenon occurs without any chemical reaction.


Foreign or undesirable material in a product or package material. The adulterant may suggest unsanitary handling, or improper manufacturing procedures. The offending material may simply be esthetically objectionable or may pose a health or environmental hazard.

advance disposal fee (ADF)

Revenue generation to cover waste disposal costs by placing a levy on packages or packaging materials at the point of production or purchase.


(a) Plastic alloys are blends of polymers or copolymers with other polymers as compared to copolymers that are compounds with chemically bound monomers in a molecular chain. (b) A metal produced from a combination or admixture of two or more elements, at least one of which is a metal.


Prevailing uncontrolled atmospheric conditions. Ambient temperature, for example, would refer to temperatures in the typical room comfort range. A specimen tested at ambient conditions would have been tested at whatever the room conditions were that day.

American National Standards Institute (ANSI)

A federation of technical societies, trade associations, and other interested parties based in New York, New York. Its main functions are to provide systematic means for developing U.S. standards and to promote the development and use of national standards domestically. ANSI does not write standards, but will approve a standard as a U.S. Standard provided it is accepted by a consensus of all national groups substantially concerned with its scope and provisions. ANSI also coordinates standardization activities and serves as clearinghouse for information on U.S. and foreign standards as well as representing U.S. interests in international standardization work.

American Society for Testing and Materials

See ASTM International.


A general term any of a group of synthetic resins containing the NH2 functional group; for example urea- and melamine- formaldehyde plastics.


Not having any definite form or shape. In packaging, used mostly to describe the structure of a polymer. See polymer, amorphous and polymer, crystalline.

amorphous phase

A phase within a plastic that is devoid of crystallinity. At processing temperatures, all thermoplastics are in the amorphous state. See polymer, crystalline.


When describing vibration, the distance from a mean reference position to the point of maximum displacement.

Double amplitude describes the distance displaced to both sides of the reference point.

anchor coat

See primer. Also tie coat.


Having no water.

anilox roll

A metal or ceramic roll with finely engraved cells across its entire surface. The size and geometry of the cells will determine the amount of ink resident on the roll. Used in flexographic printing presses to meter ink.

anilox system

An inking system used in flexographic printing presses, comprising an anilox roll and a method of applying excess ink to the roll and then wiping it clean so that only ink resident in the cells remains. Excess ink may be applied by flooding the surface of the anilox roll from a sealed ink chamber or from an elastomer-covered fountain roller running in an ink pan. The excess ink is removed by wiping with a doctor blade. The ink is transferred from the anilox roll to the print-plate cylinder.


Describes a material that exhibits different properties depending on the direction of the test. For example, paper, an anisotropic material, will exhibit different stiffness and tear properties depending on the direction of measurement.


Broadly, to control a material’s heating and cooling cycle so that internal molecular structures have time to move and assume new positions. Metals that have been hardened by rapid cooling or by work stresses are annealed to soften them and make them more malleable. Similarly plastics are annealed to remove internal stresses.


Heating a material above a critical temperature and holding it at that range for a specific period of time, followed by cooling at a controlled rate. Plastic materials that have been oriented are annealed in order to relieve internal stresses that would otherwise impart heat shrink properties.


See the American National Standards Institute.

aseptic packaging

(a) Any packaging where the contained product has been made sterile by some means. (b) In some usage, the term has become synonymous with various proprietary flexible and semi-rigid packaging such as those produced by TetraPak, Combibloc and others, where separately sterilized product is introduced into a separately sterilized packages under sterile conditions to give a shelf-stable manufactured good. The advantage of this methodology is that’s since the sterilizing of product and package are done separately, the finished package can be filled at room temperatures and pressures, eliminating the need for strong, high temperature tolerant packaging materials.

aspect ratio

(a) The ratio of height to width. A tall, thin package would have a high aspect ratio. (b) In bar coding, the ratio of the height to width of a bar code symbol.

ASTM International (ASTM)

A consensus organization for developing standards and test methods. Based in West Conshohocken, Pennsylvania, it usually is referred to as ASTM. The majority of testing procedures used in the packaging industry have been developed by ASTM committees. Most (but not all) standards concerning packaging are developed by ASTM committee D-10 and can be found Volume 15.09. Formerly American Society for Testing and Materials (ASTM).


Describes a polymer in which the pendant functional groups, for example, -CH3 in polypropylene, are randomly located around the main chain.

atmospheric pressure

Pressure exerted by the atmosphere in all directions, equal at sea level to about 101kpa (14.7 pounds per square inch).

antifoaming agent

An additive used to prevent or eliminate foaming in liquid preparations. Some inks and adhesives contain antifoaming additives.

antifogging agent

Moisture tends to condense in droplets on clear plastic films, obstructing the view of the product. Antifogging agents are surfactants that promote the deposition of a continuous film of moisture.


A substance that inhibits microbial growth.


A substance that prevents or reduces the rate of product deterioration due to exposure of the material to atmospheric oxygen. Many antioxidants work by absorbing or reacting with oxygen contained in a package.


Any material that reduces penetration into a substrate.

antislip surface

Any surface treated or prepared to have a higher coefficient of friction. Also anti-skid.

antislip treatment

A treatment that increases a material’s coefficient of friction.

antistatic agent

See static dissipative agent.

antistatic packaging

See static dissipative material.


See average outgoing quality.


See average outgoing quality level.

application rate

The amount of coating, ink, adhesive or other material applied over a given area. There are many ways of expressing this in the inch/pound system. The mass in grams per square metre is the most common term in SI metric.


Pertaining to water. A coating, ink, or adhesive formulation in which water is the solvent.

arc of contact

The angular wrap in degrees of a material around a roll.

automatic vision inspection

Technology that couples video cameras and computers to inspect items or parts. Significant features of a scanned image are compared with the same features of a good part that has been previously placed in the computer’s memory. Any difference between the corresponding characteristics of the two parts will be either within a tolerance and hence good, or out of tolerance and therefore bad.

average outgoing quality (AOQ)

The quality of outgoing product following the use of an acceptance sampling plan for a given value of incoming product quality.

average outgoing quality limit (AOQL)

For a given acceptance sampling plan, the maximum average outgoing quality over all possible levels of incoming quality.

azeotrope, azeotropic

A mixture of solvents that exhibits a constant maximum or minimum boiling point.


An intermediate, partially cured stage in the reaction of certain thermosetting resins. B-stage resins are somewhat thermoplastic: swell in contact with certain solvents, and can be worked in contrast to a fully cured resin. See A-stage, C-stage.


The application of heat to set an ink, adhesive, or coating. Bake usually implies that there is a setting or chemical change taking place beyond simply removing of water or solvents as in drying.


In pressure-sensitive labeling, the release liner.


Microscopic unicellular microorganisms that reproduce by splitting into two identical cells (binary fission). Bacteria grow exponentially and can divide as fast as every 20 minutes. Also called microbes.


A substance that will retard or stop the growth of bacteria. Bacteriostats may be incorporated into products or package materials to control microorganisms.


A preformed, flexible container, generally enclosed on all but one side, which forms an opening that may or may not be sealed after filling. May be made of any single flexible material, multiple independent layers of flexible materials, or of laminated materials. The term duplex is used to describe bags made with two layers of paper. Multiwall describes bags with three or more independent walls. The term sack, although often used as a synonym for a “bag,” generally refers to heavier duty or shipping bags.

bag liner

The inner liners of bags used for packaging coffee, tea, and other consumer and industrial products. Glassine, greaseproof paper, waxed paper, or plastic films are frequently used for this purpose in order to create the required contact surface or to provide a suitable barrier. With greasy products, liners prevent the staining of the bag material.

bag, automatic self-opening

A bag constructed with side gussets and a preformed flat, square bottom, which permits it to stand upright when

empty and that can be opened with a quick flip of the wrist. The air entering the top of the bag automatically opens the bottom. Also called SOS (self-opening square) bag.

bag, baler

A large paper sack with a square bottom.

bag, block-bottom

A paper bag where the base opens into a square form.

bag, bulk

A bag made from textile, reinforced, film, or paper, capable of carrying or holding a ton or more of loose material.

bag, carryout

A plain or decorated, usually paper or plastic, that is provided by a retailer for containing and carrying out a client’s purchases.

bag, combination

A bag, not laminated, composed of two or more materials, e.g., a film face and a paper back.

bag, crimp-bottom

A flat bag made with a crimp seal rather than a foldover; usually heat sealed.

bag, doublewall

See bag, duplex.

bag, drawstring

A bag that is closed by tightening a sliding drawstring inside the top perimeter of the bag.

bag, duplex

A bag constructed of two plies of packaging material.

bag, fashion carrier

A paper bag, usually flat or satchel style, with a large flap closure at the top. The closure is usually reinforced with board to take a carrying handle consisting of a punched board hand hole, twine, or a plastic device.

bag, film

A general classification for bags made from flexible plastic film.

bag, film-front

Usually supplied as a flat-style bag having a solid paper back and a transparent window in front for product visibility.

bag, flat

A gusset-less paper bag on which the bottom is simply folded over flat and glued.

bag, grocery

A paper bag with fitted plastic or fiber carrier handles and reinforcement at the mouth , usually in a self-opening gusseted and half-block bottom style.

bag, gusseted

A bag whose sides are folded into a bellows form that unfolds and expands when opened and filled.

bag, half-block

A modified block-bottom paper bag style in which the points on the base are folded to overlap. The open bag has a rectangular cross section.

bag, merchandise

A general classification of bags used by retail stores for various over-the-counter packaging purposes. Sizes range from100x160mm(4x6.25in)530x610mm(21x24in.)inflate and gusseted construction. Merchandise bags are standard items.

bag, mesh

A bag produced from a natural or synthetic material that has been woven into a net-like form. Mesh bags are commonly used for packaging of various produce items such as onions or potatoes. The open weave of the bag provides product visibility as well as allowing the product to breathe.

bag, multiwall

A bag having more than one wall or ply. The plies are not joined as in a lamination. Usually used in reference to paper bags constructed of multiple layers of paper.

bag, paper

A preformed flat or gusseted flexible container that is longitudinally seamed and closed at one end. It is made from one or more plies of paper, or from paper in combination with flexible materials such plastic film, foil, or multiple layers of paper. Bags are invariably supplied closed at one end by the manufacturer with closure of the opposite end affected by the user. There is no sharp dividing line between paper bags and sacks in terms of size.

bag, pasted

Typically a paper bag that has been assembled by gluing the appropriate surfaces.

bag, pinch-bottom

A multiwall bag having the bottom closed by turning it up in a single, cross-tube fold. Each inner wall is shortened to facilitate the fold, which is secured by a thermoplastic adhesive.

bag, satchel-bottom

A gusseted paper tube that has a bottom folded back and glued to form a square-bottomed bag.

bag, self-opening

See bag, self-opening.

bag, self-opening satchel

A satchel bag having a rectangular base, which can be quickly opened by snapping it in the air.

bag, self-opening square (SOS)

Self-opening square bags or sacks that will stand alone when empty. Term does not apply to satchel-bottom bags or sacks.

bag, self-sealing

A bag having a pressure-sensitive or self-adhering adhesive on its inner closure surfaces.

bag, sewn open-mouth

A multiwall bag having the bottom sewn closed leaving the top, or mouth, open for product filling.

bag, sewn-bottom

See bag, sewn open-mouth.

bag, sewn-valve

A multiwall bag having both ends sewn and a small opening retained at the corner of one end for product filling. Various kinds of sleeves are built into this valve to prevent the product from sifting out; i.e., tuck-in, internal, etc.

bag, triplex

A multiwall bag of three-ply construction, usually made of kraft paper.

bag, T-shirt

A plastic bag with gusseted sides that increase the bag’s carrying volume as well as providing for a double thickness of material for the carrying handles. Commonly used as a carry-out bag in the retail trade.

bag, zip-lock

A plastic bag with an incorporated zipper device, which can be readily opened by pulling the two sides of the bag apart and resealed by pressing the mating halves of the zipper together and running the fingers down its length. Ziploc is a registered trade name for such a system.

bag-in-box (BIB)

A packaging system in which a flexible bag or pouch is enclosed in an outer box made of a rigid material such as paperboard or corrugated. Some retail products are sold this way, but most BIB packages are found in industrial and hospital-restaurant-institutional product delivery systems.


A pressure dispensing system where the product is contained in a bag that in turn is inserted into a sealed can. The can is pressurized by a propellant and the product expelled by opening a valve similar to a conventional aerosol container. Bag-in-can systems are popular for dispensing paste products such as shaving creams.

baggy edge

Rolls of film or laminate where one side of the material coming off the roll is loose or baggy while the opposite edge is taut.

baggy, bagginess

A roll of material that has loose and tight sections across its width. A roll in which the tension is not even across the width of the roll. A slack floppy area in a web caused by the material being stretched and permanently elongated in certain areas. The bagged area will have a thinner gauge.


(a) (noun) A unit bound together under tension with plastic shrink-wrap, metal strapping or other means. (b) (verb) The act of compressing and tying materials into a large bundle known as a bale.

baler, baling press

A machine for compressing and baling scrap and other materials.


(a) A circumferential ring around a roll of material usually caused by a slight variation in material thickness. (See gauge band). (b) A secondary closure consisting of a continuous plastic liner shrunk over the cap and neck of a bottle for decoration, tamper evidence or additional protection of contents. (c) Generally, any relatively narrow strip of paper, film, metal, or other material encircling an object or package. (d) Metal or plastic strapping.

band sealer

A machine used to heat-seal the mouth of a bag by passing the mouth between two moving bands that are pressed together by heating bars. The heated bands soften and fuse the sealing surfaces of the bag. A second set of bands may be used to remove heat from the seal area.


(a) The darker element of a printed bar code symbol. (b) A metric unit for pressure: 1 bar = 100kpa. (approximately 14 pounds per square inch).

bar coater

A metal rod wound with fine wire around its axis so that liquids can be drawn down evenly at a given thickness across a substrate. The amount of liquid applied is a function of the core rod diameter and the diameter of the wire winding. The rod is rotated to distribute wear and dislodge any material accumulations against the rod. Bar coaters are used to meter lightweight coatings on smooth surfaces. Also called Mayer rod coaters.


A trade name for acrylonitrile made by BP Chemicals, Cleveland, OH.


An instrument for measuring atmospheric pressure.

barometric pressure

The atmospheric pressure at a given location.
Reported in SI units as kPa and in metric as reading millimetres of mercury. In inch/pound systems it may be reported as inches of mercury, inches of water, millibar, or pounds per square inch.

barometric pumping

The “breathing” of a package caused by changes in barometric pressure. See breathing.


In packaging, the term is most commonly used to describe the ability of a material to stop or retard the passage of atmospheric gases, water vapor, and volatile flavor and aroma ingredients.

barrier material

A material designed to prevent, to a specified degree, the penetration of water, oils, water vapor, aromatic components or other gases. Barrier materials may serve to exclude or retain such elements without or within a package.


(a) The fundamental part of a processed material, such as the film or paper base of a coated sheet. (b) The full strength of ink or tone, or generally the major ingredient used in a clear lacquer, varnish, or ink. May refer to either solvent or binder system. (c) A cylinder before it is engraved to become an anilox roll or gravure roll. (d) The bottom portion of a container, such as the bottom of a bag.

base (chemical)

An alkaline substances (pH greater than 7.0) that yields hydroxyl ions (OH-) in solution. Substances with pH values below 7 are classed as acids. See alkali.

base coat

The first applied coat of a multiple system of coatings.

base color

The first color laid down that serves as a background on which other colors are printed. For example, a metal can may be covered with a white base coat and cured. The white then serves as a background for subsequent colors.

base film, base stock

The untreated film web-stock to which print, coatings, laminations and other processes will be applied.

basis weight

Generally, the mass of a given area of a material. Older measuring systems have various traditional units depending on the material. In paper, the basis weight is the weight in pounds of a ream of paper cut to its basic size. The basis weight for most packaging papers is reported as the pounds weight of 30002 feet of paper. For paperboard and linerboard used for corrugated containers, basis weight is expressed in lb. per 10002 feet. In metric, this is reported as the grammage: the grams per metre2 of a given material.


A quantity of material handled or processed in one lot or cycle. For purposes of traceability and record-keeping batches are typically identified with a numerical or other code. Such identification is a legal requirement in some industries.


One of the many hydrometer scales used to determine the relative density of liquids as compared to a standard liquid. There are two Baume scales: one for liquids lighter than water; the other for liquids heavier than water.

bead, beading

(a) A thickened section around the edge of a roll of material. (b) The juncture of melted poly caused by a hot knife on a side-seal bag machine.

bearer bars

(a) Type-high supports at each end of a printing plate to help carry and even out the impression load and to reduce bounce. Rotary cutting dies will also position bearer bars around each end of the die. (b) In bar coding, a printed perimeter frame around a machine-readable bar code, including the quiet zones, whose purpose is to even out printing plate pressure and produce a more consistent and scannable bar code within the bearer bars. Bearer bars are particularly recommended when printing corrugated board. See also bounce.


The gussets or tucks in the sides of a bag.


A fullness in cross section of the web or foil, either in the center or near the sides. Also known as web sag or bag.


Benchmarking is a comparison or scale of product, function, practice, or strategy between identical industry segments. Functional benchmarking can be a comparison of the functional process or manufacturing technique relating to product development, packaging line design, machinery, line control, and logistics of inputs in and packages out. Utilization can be a form of functional benchmarking.


Describes the ability of a paperboard to be bent or folded on a score without splitting the top liner. A full bending board can be bent 180 degrees without showing significant failure of the top liner.

beta gauge

A measuring instrument that uses low-level radiation for measuring the thickness of film materials.

bi-directional bar-code

A bar-code symbol capable of being read independent of scanning direction.


The adhesive component that holds together the nonadhesive components of a compound mixture such as a printing ink.

bingo card

See calendar blister.


A material that is capable of being converted by microorganisms into basic elements and compounds such as carbon dioxide and water.

biological evaluation

A protocol designed to determine the microbiological integrity of the package, where the sealed package is exposed to biological indicators.

biological oxygen demand (BOD)

The quantity of oxygen used in the biochemical oxidation of organic matter under specified conditions of time and temperature.

black printer

In color reproduction, the black plate, made to increase contrast of dark tones. Black (or another dark color) is needed in process printing since no combination of the three process colors can produce a jet black. Also called the key color.


A photographic or other graphic reproduction comprised of black pigmentation over a white background.


(a) A large, usually polyester, sheet on which flexographic printing plates are mounted prior to being applied to the press. It usually has some device along both leading and trailing edges for mounting onto the printing plate cylinder. (b) See also blanket cylinder, blanket roll.

blanket buildup

An accumulation of material on the nonimage or image area of an offset blanket from various sources such as paper, ink, dampeners, and air contaminants.

blanket, compressible

A compressible material designed to withstand shocks to the printing plate and also to absorb differences in board caliper. Also called cushion stickyback.

blanket cylinder, blanket roll

A resilient rubber roll that receives the wet ink image from the printing plate and then transfers it to the substrate to be printed. Printing processes using blanket rolls are referred to

as being offset. For example lithography is always offset (uses a blanket roll). Packaging gravure is not normally offset. See also printing, offset.


(a) (noun) A chemical, such as chlorine, sodium hypochlorite, or an oxidizing agent such as hydrogen peroxide, which removes color or renders the treated material lighter in color. (b) (verb) To remove color.

bleached paper, bleached board

Any type of paper or board, made from bleached (white) pulp. Paper grades made from a mixture of bleached and unbleached pulps, or pulps bleached to an intermediate stage are called semi-bleached.


(a) The printed area beyond the item’s cut edge. Bleeds are added to a graphic design so that printed areas extend completely to the edge of the finished package, label, or wrapper, regardless of any register variation during printing or die-cutting. (b) To diffuse or run when wetted. Undesired movement of color from one surface to another.


(a) A small raised area caused by expansion as from a trapped gas or fluid beneath the surface. (b) With adhesives, a small localized area free of or freed from adhesion. The absence of adhesion in a pair of adhesive-bonded surfaces. Blisters may be caused by: 1) Lack of adhesive because of skips in its application; 2) Absence of final adhesion due to greasy or hard-sized areas, damp spots, or other contaminants that prevent wetting out: 3) Excessive penetration of adhesive into porous areas: 4) Encapsulation of residual solvents between two nonporous substrates.

blister card

See blister packaging.

blister, double

See clamshell.

blister packaging

A package type where the item is secured between a preformed (usually transparent plastic) dome or “bubble” and a paperboard surface or carrier. Attachment may be by stapling, heat-sealing, gluing, or other means. In other instances, the blister folds over the product in clam-shell fashion to form an enclosing container. Blisters are most commonly thermoformed from polyvinyl chloride, however, other thermoplastics are also used.


(a) A solid form, such as a core in a die, over which a part is shaped. (b) A barrier. (e) (verb) To form a part over a solid core of desired shape.

block color

A color printed as a solid mass of constant density without gradations, tints, or tones.


(a) An undesired adhesion between touching layers of a material, as might occur under moderate pressure and/or temperature during storage or use. A common problem with plastic rollstock, stacked plastic sheets, and tapes.

blocking resistance, block resistance

The characteristic of a material that allows it to resist blocking. Blocking resistance is typically developed in plastic films by the addition of various anti-blocking additives.


(a) (noun) Material migrating to the surface. An exudation of an ingredient from a product as visibly evidenced on the product or package. For example, plasticizer from poly(vinyl chloride). (b) A surface film on packages or packaging materials resulting from attack by the atmosphere or from the deposition of smoke or other vapor. (c) (verb) To undergo a process resulting in bloom. See also blushing.

blow hole

In shrink film, a hole or area melted through by excessive heat or poor sealing.

blow-up ratio

(a) In blown film manufacture, the ratio of the expanded film bubble to the initial extrusion diameter. (b) In extrusion blow molding, the ratio of the parison diameter to the maximum mold cavity diameter.

blowing agent

A substance used to generate gas, either by chemical reaction or evaporation, to cause a resin to expand into a cellular structure. The blowing agent may be a substance that is a liquid at room temperature, but that boils away at some elevated temperature to produce the gas that will expand the plastic. Low-boiling-point hydrocarbons and halogenated hydrocarbons are commonly used as blowing agents.


An enlargement of a photograph or image.


(a) Defects in the appearance of lacquer-type coatings resulting from the condensation of water from the ambient air, most likely to occur in periods of high humidity. Blushing can occur when the rate of evaporation of volatile organic solvents from the solvent-containing material is sufficient to lower its temperature to the dew point. Blushing may be avoided by use of a retarded or “slow solvent” to reduce the rate of evaporation, however, this will in turn, delay the setting of the coating. (b) A milky, foggy or flat appearance in an ink or coating due to precipitation or an ingredient incompatibility. (c) A defect appearing in plastic sheet during thermoforming wherein the sheet develops a white spot or “blush.”


See biological oxygen demand.


(a) In viscous fluids such as adhesives, paints or inks, the term body is used to give a qualitative indication of consistency, related to viscosity. (b) Principal part of a container, usually the largest part in one piece containing the sides.


A significant increase in viscosity of an ink or coating.


A flexible package usually containing a food product, that can be placed into boiling water to reheat it for serving. The bag or pouch material must be able to tolerate this treatment. Laminates are typically based on nylon or poly(ethylene terephthalate) and use adhesives capable of maintaining a bond at boiling temperatures.


(a) (noun) The junction between two materials that have been joined. (b) (verb) To attach materials together by adhesives. (c) Name originally given to a paper that was used for printing bonds and stock certificates.


The state of two materials being joined together with a medium such as adhesive.

bond, internal

Usually used to describe the internal separation strength of a paperboard sheet. Also called Z-direction strength.

bond line

The adhesive layer between two bonded substrates.

bond strength

The strength of an adhesive bond.

bond, fiber-tear

In an adhesively bonded paper assembly, the tear of fiber as opposed to separation of adhesive when the assembly is pulled apart. If the adhesive bond is weak, separation will occur at the paper-adhesive interface rather than the paper fiber. An adhesive bond cannot be stronger than the bond strength of the surface fibers to the underlying substrate mass.

bond, peeling

(a) A bond where two adhered paper surfaces may be pulled apart without the tearing of the fibers. The amount of force necessary to separate the two sheets determines the strength of the adhesive bond. Use of qualifying words such as “strong peeling” or “weak peeling” often helps describe bonds of this type. Opposite of tearing bond which pulls fibers apart before the adhesive separates. (b) Any bond where failure occurs in the substrate before the adhesive.

brand consciousness

See brand awareness.

brand image

The real or perceptual qualities attributed to a product by consumers.

brand loyalty

Consumer faithfulness to a particular brand, and the reluctance to purchase similar competitive products.

bread wrap

Thin paper, usually glazed imitation parchment or bleached kraft waxed after printing. Currently largely supplanted by film.

break, break for color

In artwork, the separation of the image to be printed into different colors.


Passing a material such as paper over a dull edge in order to remove curl.


The rupture of web stock during processing. Used mostly to describe paper rupture.

breaking strength

A measure of the force required to break an object or material.


Describes packaging that is freely able to allow the permeation or circulation of air or other gases. For example, all fresh produce respires and therefore must have access to oxygen. By definition a breathable package requires low barrier materials or designs.


(a) A desiccant-containing device that may be inserted into an opening in a moisture barrier package so that air which is breathed in by virtue of atmospheric pressure changes will be dehydrated before entering the package. (b) A sealed container that allows air to enter without allowing bacteria to enter.


(a) The passage of gases into or out of a package through an opening as a result of variations in external pressure. (b) Controlled passage of gases through a packaging material.

brick pack

(a) A paperboard container that incorporates an aluminum foil barrier and polymer components, which seal the aluminum foil to the paper and enable the container to be hermetically closed by heat sealing. (b) An aseptic package used for juice and milk products.

bond, tearing

A paper bond having sufficient strength that is necessary to tear fibers of one or the other adhered surfaces in order to separate them, while, at the same time, there is no failure in adhesion or cohesion of the adhesive. See bond, fiber-tear.

bond, zippery

A peel-able bond characterized by the brittle failure on one or more surfaces of the lamination being tested.

bonding range

The time after the adhesive is applied within which a satisfactory bond can be made when the substrate surfaces are brought together. See also open time.

bonding, dry

The process of laminating or joining two surfaces using an adhesive system from which all solvents or volatiles have been removed prior to the mating of the surfaces. Dry bonding must be used when joining any two surfaces that are not porous enough to allow the rapid escape of volatiles.

bonding, extrusion

A process wherein a film of molten polymeric material is extruded and immediately pressed between two substrate materials while still hot. The cooled polymer will bond the two materials together.

bonding, solvent

The joining of articles made of thermoplastic resins by applying a solvent capable of dissolving the surfaces to be joined, and pressing the softened surfaces together until the bond has gained strength. Adhesion is attained by diffusion of liquefied polymer molecule chain segments across the interface, followed by solvent, evaporation or absorption of it into adjacent material. Acrylonitrile-butadiene-styrene, acrylic, cellulose acetate, propionate, and butyrate, polycarbonate, polystyrene, and vinyl are plastics able to be joined by solvent bonding.


See polypropoylene, biaxially oriented.


Rotating printing or die-cutting cylinders will experience different pressures during rotation as greater or lesser areas are pressed against the impression cylinders. This can result in erratic movement or bounce of the cylinder. Bounce can be reduced by incorporating bearer bars into the plate or cutting die.


Describes a polymer chain that has additional side chains branching away from the main or linear chain. Also branched.


The design, graphics, trademarks, and other features that call attention to the product and make it easily recognizable to the consumer. Specific brand markings and features are usually protected as registered trademarks. Overall brand appearance, sometimes referred to as trade dress, may be challenged if it is judged to cause confusion as to its true identity in the marketplace.

British Standards Institution

A British equivalent to ANSI based in London. Often referred to by acronym BSI.

Brookfield viscometer

The Brookfield Synchrolectric viscometer is the most widely used instrument for measuring the viscosities of adhesives and other liquids. A synchronous motor provides a selection of four or eight spindle speeds. Near the tip of the spindle, is either a crossbar or horizontal disk whose drag torque in the liquid is detected by a torsion spring. By taking readings at different rotational speeds, one can study such viscous flow phenomenon as thixotropy and pseudoplasticity.


See British Standards Institution.


See British thermal unit.


(a) In blown-film extrusion, the expanding tube moving from the die to the collapsing rolls at the top of the tower. (b) A void within a molding or an extrusion.


Deep narrow folds in a rolled material, generally running in the transverse (cross) direction.


A buffer shields or cushions an upstream machine from a downstream machine that stops or slows down (via conveyor length or off-load areas to let the inputs gather). Generally, buffering is a technique used to maintain uptime and improve utilization. It should not be confused with accumulation. See accumulator.

build up

(a) Rebuilding a roll diameter to original factory manufacture (OFM) operating tolerances by plating or welding material to the base roll. (b) Material that clings to machine parts. See also blanket build up.

bulk, bulk factor

(a) A comparison of a sheet material’s density compared to its thickness. (b) Ratio of the volume of loose molding powder to the volume of the same weight of resin after molding.


(a) (noun) A package that is formed by utilizing the contents as a mandrel around which flexible packaging material is wrapped and sealed. The contents are thus unitized for handling and shipping. (b) Two or more articles bound or rolled together usually without compression, so as to form a package or pack. See bale. (c) (verb) To wrap a combination of several small unit-packages into a single unit, usually by machine.


In the manufacture of printing plates, a term used to describe the exposure of the plate to a light source in order to develop or fix an image.

bursting pressure

(a) The internal pressure at which a container will burst. (b) The pounds per square inch required to burst a paperboard or other material when conducting a Mullen burst test. See bursting strength.

bursting strength

A measure of the ability of a sheet to resist rupture when pressure is applied to one of its sides by a specified instrument under specified conditions.


A monomer with the structure (CH2=CH-CH=CH2).


See coated two sides.


Cellulose acetate. See also cellulosic.


See cellulose acetate-butyrate.


Acronym for computer-aided design. Use of a computer and drafting software to produce and store graphic or engineering prints for layout, installation, machining, assembly, and fabrication. Also the use of computers in interactive engineering drawings and the storage and retrieval of designs.


Acronym for computer-aided design/ computer-aided manufacturing. The term implies the use of a computer and post-processing or linking software to manipulate and compile design data into a machine language for a machine(s) to execute the desired function.


(a) The collecting of dried ink on rollers and plates. (b) The formation of a cake or lump of a powdered or granular material, usually caused by ingress of moisture to contents of a package.

calendar blister

A large calendar blister card designed for ease of use and to assist in patient compliance. Normally will hold a month’s supply of medication, although other time frames also are produced. Also bingo card.


(a) (noun) A group or stack of rollers through which sheet material is passed, under controlled conditions of heat, pressure, and/or time, in order to alter the thickness, density, or surface finish. For example, in papermaking, a set of heavy metal rolls resting on one another in a vertical stack at the end of a papermaking machine. Paper is passed between some or all of the rolls to increase smoothness and surface gloss, or to densify the paper coatings or other additives may be applied during calendering operations. (b) The equipment used in heat-transfer printing through which designs are melted and transferred to a substrate. (c) (verb) To pass through a calender. Calendering. (d) Calendered: Having been passed through a calender.

calender cuts

Paper defects caused by the creasing or cutting of wrinkles in the paper during calendering.

calender stack

A group of rolls through which material is passed to reduce thickness, increase density, and improve surface smoothness and gloss.


The process of determining the error of a measuring technique or instrument by comparing its readings with the values of known standards, or the readings of a more accurate technique or instrument. In its strictest sense, calibration of a measuring instrument implies traceability to a national standard.


(a) The precision instrument used to measure thickness. (b) (noun) The thickness of a material such as paper, film, or foil, measured under specified conditions. (c) (verb) To measure with a caliper.

can composite

Any can manufactured or assembled from two or more materials. In most instances it refers to cans with convolute or spirally wound paperboard bodies and applied metal, plastic or paper ends. See can, fiber.

can, convolute

A can with the body made of fiberboard formed by convolute winding of paper to build up the required thickness. The paper or winding material advances to the mandrel in a direction perpendicular to its axis. A tube is formed by having each ply wrapped around itself and placed directly over the preceding ply. The length of the tube is the same as the width of the paper from which it is wound. See can, fiber.

can, fiber

A rigid container having a body constructed almost completely of lightweight paperboard fiber stock, which may be lined, treated, or coated to achieve desired chemical and physical characteristics. The can ends may be made of paperboard, plastic, or metal. The body may be spirally wound, convolute wound, or it may be laminated or lapseamed from an appropriate number of supplies built up to the desired strength characteristics. Fiber cans may be round, oval, or oblong.


See controlled-atmosphere packaging.


A relative measure of how capable, or effective, the actual packaging process is to produce the appropriate volume of needed packages within the planned plant operational time period or schedule.

capacity, package

May refer to the rated volume of a package for a given product or the total volume inside a package. The latter is more correctly called the overflow capacity.

capacity, machine

Capacity for a given machine or line is the upper sustainable limit passing a specified point in a given time period. In some usage capacity is the speed at which the percentage of rejects and/or jams begins to rise in a nonlinear manner. Capacity is usually expressed as a rate (packages or length per minute). Typically, a line will operate at a somewhat lower speed, called the actual set run speed.

carbon black

A black pigment produced by the incomplete burning of natural gas or oil. Carbon black has good ultraviolet barrier properties.


Any material that can cause cancer.


a stiff paper or paperboard used as a stiffener or backing sheet in packaging. Card does not specifically denote a particular paper composition.


A general term for a paperboard 150 micrometres (0.006 inches) or more thick. The word has been adopted by the public to describe various materials including (incorrectly) corrugated board.

carded packaging

Packaging systems based on holding the product against a stiff paperboard backing card. Product attachment might be with a preformed plastic blister (blister package), with a plastic film drawn in tight conformance with the product (skin packaging), or by mechanical attachments such as twist ties, staples, or tapes. Carded packages are usually displayed on Peg-Boards and have the advantage of providing good product visibility and display.

carrier web

A sheet of material whose purpose is to support or carry another material. For example, pressure-sensitive labels are supported by a carrier web, often referred to as a release liner or paper in this application. Heat-transferred printing inks and metallized decorations are most typically supported by a poly(ethylene terephthalate) carrier web to the point of use.


A folding box generally made from paperboard. In domestic commerce, the term “carton” is generally recognized as the acceptable designation for folding paperboard boxes but never for a shipping container. In maritime and export usage, the term carton refers to a corrugated or solid-fiber shipping container.


A paperboard used for folding cartons and made from furnish designed to produce a stock that is bendable enough to be folded without cracking along score lines.


A non-specific term for a box or container. Avoided in some instances because of possible confusion with “case” used to indicate “in this instance”. For example in the statement: “Damage was observed in three cases”.

case hardening

The drying of a coating’s exterior surface while the internal volume is still not fully dried. Case hardening can lead to defects such as checking.


A protein-based adhesive made from acidified milk curd. Used to make sizings, adhesive solutions, and coatings. Casein adhesives have good cold-water resistance but can be readily dispersed in hot caustic solutions. This property makes them ideal for labeling refillable beverage bottles, where the label must resist cold-water immersion but must be readily removed at the refill point.


A product ready for display as delivered to the retailer. Used in particular with reference to meats and produce, which traditionally have required some preparation at the point of sale.

casing, food

A flexible tubing into which foods are stuffed to provide a skin-tight covering. Used in packaging prepared meats, poultry, cheese, and other food products. Casings may be made of animal protein or synthetic materials such as regenerated cellulose, or various plastics.

casting; casting, extrusion

The manufacture of unsupported thermoplastic film or sheet by casting a thin curtain of molten resin onto a chilled revolving drum. After the plastic cools and solidifies, it is edge trimmed and wound onto rolls for further processing. See film, cast and film blown.


A chemical substance that initiates or accelerates a chemical reaction but is not itself changed by the reaction. For example, when added to coating materials or adhesives, catalysts will promote cure at lower than normal bake time or temperature, or both.

catch weight, catchweight

A term typically used in packaging fresh produce and meat to indicate random weights; opposite of “set” or uniform weights. In catch weighing, the items are packaged just as they are received without attempting to select items of a uniform or predetermined weight and are marked with their actual respective weights.


Materials having a pH level above 7. Like acids, caustic materials can be corrosive. Also known as alkalines or bases.


(a) Individual wells or depressions chemically etched or mechanically engraved into the surface of a gravure print cylinder or a flexo anilox roll. The cells meter, retain, and transfer ink in the gravure and flexographic printing processes. Such cells will have various geometries depending on the specific application. (b) An individual void in an expanded or cellular plastic. If the cell is totally enclosed by walls, the structure is said to be closed cell. If the cell is not totally enclosed but interconnects with other cells, the structure is said to be open cell.

cell, channel

Engraving on an anilox roll where a channel is cut between cells to assist in ink release.


Transparent film made of regenerated cellulose, a process wherein natural cellulose is altered to make it soluble and then regenerated to its original state by casting the soluble intermediate into an acid bath. Cellophane is a thermoset plastic and cannot be processed by the usual thermoprocessing methods. Once the predominant clear packaging film, cellophane has been almost entirely replaced by polypropylene and other synthetic polymers.


A Union Carbide trade name for ethylene monoethyl ether solvent. Cellosolve is used as a retarding solvent in some printing inks.


A carbohydrate constituent of the walls and skeletons of vegetable cells. Cellulose typically occurs in a fibrous form, with each plant species having a characteristic fiber form. Long fibers are particularly desirable for papermaking.

cellulose acetate (CA)

A thermoplastic material made by the esterification of cellulose with acetic anhydride and acetic acid. Cellulose acetate can be extruded or cast into a transparent film, molded, or fabricated into various shapes. Hydrocarbon-based synthetics have replaced CA in many packaging applications.

cellulose propionate (CAP)

A thermoplastic material made by the reaction of propionic acid and a hydride with wood pulp or cotton linters in the presence of a catalyst. Cellulose propionate may be extruded or injection molded and has high moldability. Hydrocarbonbased synthetics have largely replaced CAP in packaging applications.

cellulose, regenerated

The raw basic ingredient used to manufacture cellulose-based polymeric materials such as cellulose propionate, cellulose nitrate, and cellophane. Hydrocarbon-based synthetics have replaced cellulose based polymers in most packaging applications.


There are three major cellulosic groups within which there are many different grades. The main groups are cellulose acetate, cellulose acetate-butyrate and cellulose propionate. These are often referred to simply as acetate, butyrate, and propionate. Hydrocarbon-based synthetics have replaced cellulose based polymers in most packaging applications.

cement, cementing

Sometimes used to describe an adhesive, similar to the term “glue”, or the act of joining two substrates with cement (adhesive). The packaging definition is not related to construction materials such as concrete or Portland cement.


A depreciated term for a temperature scale having 0 and 100 degrees as the freezing and boiling points of water. The internationally recognized term for this temperature scale is Celsius.

certificate of compliance

A document signed by an authorized party affirming that the supplier of a product or service has met the requirements of the relevant specification, contract, or regulation.

certified material test report

A document attesting that the material is in accordance with specified requirements, including the actual results of all required chemical analyses, tests, and examinations.


Acronym for Code of Federal Regulations.


Acronym for Current Good Manufacturing Practice. See good manufacturing practice.


(a) A printing ink condition in which the pigment is not properly bound to the paper and can be easily rubbed off as a powder. (b) A form of coating deterioration characterized by the formation of a loose chalk-like powder on the film surface.

change parts

Set of machine parts necessary to convert a machine to operate on any given size of package or product type.


The resetting or reconfiguring of a machine or production line to run a different product or package.

changeover time

The time required for resetting or changing a machine or line from one production operation to another. Changeover time includes the time from the moment of stopping the production of one product to the full-speed production of quality product in the new format. It includes: preparing for a changeover from one production operation to another - removal and replacement of change parts - alignment, adjustment, and calibration of all line elements - all subsequent activities including run-in time before the machine is operating at the required set-speed and producing quality packages.


A tunnel-like delamination in a laminated material. See tunneling.


(a) An individual letter, symbol, or punctuation mark that makes up a full typeface. (b) In bar coding, a single group of bars and spaces that represents an individual number, letter, or mark in a bar code.

check character

A character included within a UPC bar code whose value is used for the purpose of performing a mathematical check to ensure the accuracy of that message. Also called a check digit.


Fine lines in a coating’s surface. See crazing.

check weigh

Verifying consumer packages on a scale to ensure that it contains as much product as the label states. Check weighing also may be used for counting discrete objects, and to control losses through overfilling.

chemical resistance

The ability of a material to remain unchanged following contact with chemical agents. Chemical resistance implies that there is no significant chemical activity between the contacting materials. Chemical resistant properties can include stain resistance, swelling resistance, and corrosion resistance.

child-resistant packaging

A package or closure designed so that young children have difficulty opening the container. Child-resistant closures are designed to take advantage of a child’s limited ability to combine motions. In most countries, child-resistant closure requirements are defined by law. ASTM D 3475, Standard Classification of Child Resistant Packages lists nine categories of packaging and sources of each. In the United States “Child-resistant” indicates that a package will pass a test protocol administered by the Consumer Product Safety Commission. In Canada, test protocols are the responsibility of The Canadian Standards Association.


The term “childproof” should not be used to describe a package since the term suggests absolute effectiveness. Standard tests for child-resistant closures allow for a small success rate when tested on children within the specified age range. The correct term is child-resistant.

chill roll

A metal roll or drum cooled internally with water or other coolant. Chill rolls are used to remove heat after processes such as thermal drying or casting of molten polymer into film.


A low-quality paperboard made of recycled paper for use where specified strength or printing quality is not necessary. It may be a bending or nonbending grade. Chipboard is used for pads, dividers, backing sheets, and filler pieces.

chipboard, bending

A grade of paperboard used in the manufacture of folding cartons. It is composed principally of recycled paper and can be bent 180 degrees without breaking or separating plies.


Used in either elemental or combined form for bleaching pulp in the papermaking process. Chlorine is also a constituent of important polymers such as poly(vinyl chloride) and poly(vinylidene chloride). Elemental chlorine is a toxic and corrosive gas and a constituent of highly toxic organic compounds such as dioxin. On this basis, the use of chlorine and chlorine-containing materials has been challenged by some environmental bodies.

chlorofluorocarbon (CFC)

A group of chlorinated compounds mainly used as propellants in aerosols and as blowing agents for some plastics until the late 1980s. Concern over depletion of the ozone layer has virtually eliminated chlorofluorocarbons from packaging applications.

chlorotrifluoroethylene (CTFE)

A plastic material characterized by exceptional moisture and good oxygen-barrier properties as well as good clarity and easy thermoformability. Its cost restricts it mostly to the pharmaceutical industry. More properly described as polychlorotrifluoroethylene (PCTFE). Aclar is a trade name for a product based on chlorotrifluoroethylene.


Intensity or purity of a color or the lack of white or gray. A Munsell Color Space Model term that specifies the strength or saturation of a color.


A process in which a gas or liquid solution moves through a hollow tube (column) containing a subdivided solid phase into which some components of the solution are absorbed to varying degrees. This is followed by pure carrier gas or solvent and the exiting flow is monitored by a detector system. Smaller molecules are more quickly and thoroughly absorbed than larger molecules, and therefore larger molecules emerge first, smaller ones later. The detector signal is proportional to the concentration of each species in the effluent. Some variations of the process are gas chromatography (the gas mixture is passed through a porous bed, or through a capillary tube lined with an absorbent liquid or solid phase); paper chromatography (a drop of specimen is placed near one end of a porous paper), and thin-layer chromatography, (the sample is placed on an absorbent cake spread on a smooth glass plate). See chromatography, gas.

chromatography, gas (GC)

An instrumental method of accurately determining the composition of volatile solvents and oils, and their residual presence in materials such as laminates or plastics. The specimen is vaporized and introduced into a carrier gas (usually helium) that is passed through a column packed with adsorbent particles. Volatile components are first adsorbed from, then desorbed into the ongoing stream of carrier gas at characteristic rates that separate the stream into its constituent molecules. The exit time and the quantity exiting are detected, usually by thermal detectors, and recorded on a strip chart. The identities and relative concentrations of the sample constituents may be determined from the peak positions and areas. See also chromatography.

chub pack

A cylindrical package, sausage-like in appearance, made of flexible packaging materials, with ends sealed by metal clips or other means. Chub packs are used to contain semi-solid materials such as cheese spreads, meat luncheon spreads, explosive slurries, frostings, frozen bread dough, and drywall compound to name a few.


Devices inserted into a roll core to support it and allow mounting it into a roll stand.


See Commission Internationale de l’Eclairage.


Acronym for computer-integrated manufacturing. A manufacturing operation that is totally integrated with computer- based data communications systems and a management philosophy that emphasizes digital information flow and knowledge exchange between humans, humans and ma- chines, or machines and machines.

clamp mark

Marks on a material made by clamps that have been used to hold the stock in position for an operation. For example, marks on paper resulting from the clamps holding the paper while cutting with a guillotine.


A blister package in the form of two hinged plastic shells or bubbles. Clamshell blister packaging has the advantage of providing total product visibility. Some clamshells are made to be reclosable.


Freedom from translucency or haze. In flexible packaging materials, clarity is quantified by measuring the transmission of a light beam projected through the film. Clarity is expressed as a function of the transmitted light. (Reference method: ASTM D 2457.)

Class 100, Class 1000

Refers to work areas in which the air contains no more than 100 (or 1000) particles 0.5 micrometre in size or larger per cubic foot. Pharmaceutical products often need to be packed in areas with specified particulate levels.

clay coated paper, paperboard

A paper or paperboard that has had its surface smoothed and leveled with a clay-coating. The coating may contain other mineral ingredients besides clay. See clay.

clay lift

The failure of a clay coating to adhere firmly to the substrate paper stock. Clay lift is often responsible for what is sometimes classed as an adhesive failure, when in fact the adhesive has formed a satisfactory bond with the clay surface of the paper, and the failure has actually occurred at the clay\paper interface.


Tendency of adjacent film materials to adhere to each other. In most instances the mating surfaces can be separated without visible damage. Cling is a desirable attribute and deliberately introduced for applications such as stretch and cling wrapping. In most other applications, cling is detrimental. See also blocking.


Any device used to close a bottle, jar, can, or similar container to retain the contents. Most closures are held in place by a screw thread. However, closures may also snap over the finish, plug into it, or fasten in another way. A closure may be required to effect a hermetic seal to preserve the contents.

closure liner

A layer of material placed inside a closure to provide a cushion to which the container finish is held by compression, thus forming a seal that prevents leakage, evaporation, or the entrance of air into the package. Traditional liners are formed from a soft, resilient backing piece (for example, a pulpboard or cellular plastic) and a facing material selected for chemical compatibility and barrier characteristics appropriate to the product. Flowed-in liners are plastic compounds (usually vinyls) that combine the functions of the backing and facing materials and are applied in liquid form and then cured.

closure, sewn

A bag closure stitched on paper or textile bags and sacks.

closure, tamper-evident

A closure system having an indicator or barrier to entry,

which, if breached or missing, can reasonably be expected to provide visible evidence to consumers that tampering has occurred. “Tamper-resistant” is a depreciated term for tamper- evident (TE).


Cyan, magenta, yellow, black — subtractive primary colors, printing colors for process color reproduction.


See computer numerical control.

coat, coating

(a) (verb) To apply a layer of a liquid substance to the surface of a material or object. The objective might be protective, decorative, a primer for subsequent coatings, improved barrier properties, waterproofing, antistatic and so on. Coating does not usually include the application of a layer or ply of preformed dry material by laminating. (b) (noun) The applied material.

coat, anchor

A coating applied to the surface of a substrate to effect or increase the adhesion of subsequent coatings. See also primer.

coat, flood

The coating of an entire surface with an ink, adhesive, varnish, or other material.

coat, prime

A coating applied over a substrate for the purpose of improving an ink or adhesive bond.

coated one side (C1S)

Refers to a paper or paperboard that has been clay-coated on one side.

coated two sides (C2S)

Refers to a paper or paperboard that has been coated with clay on both sides.

coater, roll

A machine that uses various roll configurations to apply coatings or adhesives to a substrate.


An outer covering of a film or web that was applied as a fluid and subsequently dried or cured.

coating weight

The amount of coating material applied to the base material. For films, in the inch/pound system, this is expressed in a number of ways including mixed inch/pound and metric measures. In the metric system, all coatings are expressed as grammage; the mass per 1 square metre.

coating, antifog

A coating applied to packaging films that inhibits the condensation and accumulation water droplets on the inner surface. See antifogging agent.

coating, barrier

(a) Most commonly, any coating applied to a material whose purpose is to reduce or stop the permeation of a specified gas through the material. (b) In some instances the provided barrier may be towards liquids such as water, oils or greases. See barrier and barrier material.

coating, blade

A method of coating using a flexible blade set at a calibrated distance from the substrate surface. The blade smoothes and evens an excess of coating applied just prior to the blade.

coating, double

Application of one coating over another.

coating, engraved-roll

See coating, gravure.

coating, exterior

(a) A coating, formulated to withstand exposure to sunlight, and suitable for outdoor use. (b) Any coating applied to the outside of an article may be referred to as an exterior coating.

coating, extrusion

The extrusion of a thin molten polymeric film onto the surface of a substrate material and cooling to form a continuous coating.

coating, film

Essentially a polymeric film usually applied to a base film or foil to impart protective, decorative, or hot-sealable properties. Usually applied as hot melts or dispersions. Can be applied as a solution, and the solvent removed by evaporation.

coating, glass

A technology wherein silicone oxide (SiOx) is deposited onto plastic film. The light deposition of SiOx (glass) is similar to aluminum deposition during vacuum metallizing in that the resulting material remains flexible. Like aluminum, the addition of a layer of SiOx significantly improves gas and aroma barrier, with the added advantage that the coating is clear.

coating, gravure

A roll-coating process in which the amount of coating applied to the substrate web is metered by the depth and geometry of an all-over engraved pattern in the application roll. The process may be direct, where the gravure roll transfers material directly to the substrate, or it may be offset, where the coating material is first transferred to a resilient offset roll between the engraved roll and the substrate.

coating, heat-seal

An adhesive coating applied to a packaging material that is capable of being activated by heat, pressure, and dwell time to form a bond. The coating may be applied as a hot melt (for example, waxes or resins), from a solvent solution, or from a water emulsion.

coating, high gloss

A coating that provides a high level of surface sheen or reflectance to the applied surface. See gloss.

coating, hot-melt

A thermoplastic adhesive, applied to a substrate at temperatures from 75 to 230oC (170 to 450oF). The coating is usually activated by the application of heat at some later manufacturing stage.

coating, kiss-roll

A process by which thin coatings can be applied to substrates such as paper. A roll immersed in the coating fluid transfers a layer of coating to a second roll from which a portion of the layer is transferred to the substrate.

coating, knife

A coating method where an excess of material is applied and then leveled and metered by a knife or blade set at a calibrated distance above the substrate. Knife coaters have the advantage of being able to level a substrate with surface irregularities.

coating, pattern

The application of a material such as a varnish or an adhesive in a specific pattern. Pattern-coated adhesives, typically cold- or heat-seal, eliminate the need for adhesive application equipment during the packaging operation.

coating, photopolymer

A coating that will polymerize on exposure to light to produce a solid, light-stable material. Photopolymers in various forms are most commonly used to prepare printing plates using photographic techniques.

coating, protective

A coating that protects a material or printed surface from such events as abrasion, sunlight, moisture, chemicals, or other outside degrading influences.

coating, reverse-roll

A method of applying coatings using revolving rolls. Simple machines have three rolls: two of metal (metering roll and applicator (casting) roll) and a resilient rubber-surfaced roll (backing roll). The metering roll determines the amount of coating on the Pan applicator and the applicator roll transfers coating to the web as it passes around the backing roll. The applicator roll is turning in the opposite direction to the travel of the substrate. Reverse roll coater designs may also include engraved cylinder metering, doctor blades or additional rolls.

coating, ultraviolet

Coatings that consist of monomeric or prepolymer substances and a photoinitiator and that are polymerized in the presence of ultraviolet (UV) light. See ultraviolet listings.

coating, vinyl heat-seal

A coating used for applications such as heat sealable lid- stock to facilitate sealing to polyvinyl chloride or to polystyrene.

coating, water-based

Coating formulations that contain polymeric components suspended, emulsified, or dissolved, in an aqueous carrier.

coating, web

A process where coatings are applied to continuous substrates such as papers, plastics, and metal foils. Gravure and extrusion coating are the most common methods. There are a great number of other systems that might be employed some of which are: calender coating, air knife coating, roller coating, and kiss coating.

coating, weight

The amount of coating material applied to the base material. For films, in the inch/pound system, this is expressed in a number of ways including mixed inch/pound and metric measures. In the metric system, all coatings are expressed as grammage; the mass per 1 square metre.


The formation of undesirable threads of adhesive or coating during application.

Code 39

A machine-readable bar code where each character is made up of nine elements (four bars and five spaces). Three of the elements are always wide. Separate characters are defined by intercharacter gaps. Code 39 is a variable length code in that no fixed number of characters makes up a code. Standard Code 39 can encode 44 different characters, while an expanded version can encode the entire 128 character ASCII set.

code number, free-standing

Machine-readable code numbers printed only as human- readable form at some location on the container other than adjacent to the bar code. The number is normally printed in a fairly large font and helps stock pickers identify containers in a warehouse location.

code reader

A photoelectric or magnetic device that detects a code imprinted on a package and produces appropriate output signals identifying the code.

coefficient of expansion

The fractional change in length (or volume) of a material for a unit change in temperature.

coefficient of friction (COF)

A measure of the slipperiness of a surface determined by observing the force required to pull a known weight over a surface. Static COF is the force required to initiate motion while dynamic COF is the force required to continue the movement of the one surface over the other. Static COF is always greater than dynamic COF. As a general rule, low coefficient of friction allows for lower power requirements and easier machining where flexible materials are being pulled over stationary machine parts. However too low a COF can also result in telescoping rolls and packages that will slide at very low angles.

coefficient of friction tester

An instrument for measuring slip resistance of various substrates. There are several methods that are used including determining the angle of an inclined plane at which a package begins to move or noting the force required to pull a known mass over the test surface. See coefficient of friction.


The extrusion of two or more materials simultaneously through a single die in such a way that the separate materials fuse together to form a single structure. A separate extruder is required for each material to be coextruded. The materials still retain their individual properties except for the immediate contact area.


See coefficient of friction.


(a) The tendency of a mass to hold together. The internal bond strength due to the mutual attraction of molecules for one another within a material. (b) The ability or tendency of a material to adhere to itself. Some adhesives, for example, cold- seal adhesives, make use of this property. See adhesive, cold- seal.

cohesive failure

An adhesive failure characterized by adhesive being present on both separated substrates, that is by the splitting of the adhesive layer. This will occur when the bond strength of the adhesive to the substrate is greater than the internal cohesive strength of the adhesive.

cohesiveness, cohesive strength

Cohesiveness describes the internal bond strength of a material’s molecules. See cohesion.

cold color

A color with a bluish cast.

cold cracking

The embrittlement and subsequent cracking or breaking of coatings, adhesives, or plastic materials at reduced temperatures.

cold flow

(a) The flow and subsequent non-recoverable deformation of a viscous or a viscoelastic material over time when subjected to a load. Usually used in reference to plastics. (b) Dimensional change with time of a plastic under load at room temperature; steady deformation under stress. Also known as creep.

cold seal adhesive

See adhesive, cold seal.

cold water waxing

Applying a molten wax coating and then chilling it in cold water.


A stable dispersion of extremely finely divided material throughout a vehicle. The particle size is generally in the range of 0.1 and 50 micrometres. Colloids have little or no tendency to dialyze and have small or zero freezing-point depression.

colloidal suspension

A mixture of a liquid with particles of an insoluble substance so small that they will not settle out.

color burnout

An objectionable change in the color of a printing ink, that can occur either in bulk or on the printed sheet. In the former case, it is associated primarily with tints and is caused by a chemical reaction between certain components in the ink

formulation. In the latter case, it generally is caused by heat generated in a pile of printed material during the drying of an oxidizing type of ink.

color cast

An overall color imbalance in an image similar to what might be seen if the image was viewed through a colored filter.

color comprehensive

Design work that illustrates in detail all elements of the proposed finished reproduction, such as size, layout, color, copy positioning, type, and style.

color concentrate

A measured amount of pigment or coloring material incorporated into a predetermined amount of carrier polymer. The concentrate is then mixed into the plastic material to be used for molding, most typically as the plastic is being fed into an extruder’s feed hopper. The concentrate is accurately metered in order to produce the precise, predetermined color specified for the part. See master batch.

color control

The measures taken in all of the steps involved in the production of a printed material to insure matching as well as uniformity of color in the result.

color control chart

Chromatic color tone standards, against which colored materials or printing may be compared, to aid in developing uniformity or consistency of color tones.

color correction

Any method used to improve color rendition.

color fastness

The ability of a coloring material to retain its color after extended periods of time and exposure.

Color Key

A series of photographic positives, usually of cyan, magenta, yellow and black (CMYK) and a limited number of line art colors developed on clear film sheets. The individual Color Keys are overlaid in register, and tacked onto a mounting paper along one edge. This allows individual layers to be lifted for inspection. Color keys are useful to show how the color image will be assembled but are not as accurate in reproducing colors as other proofing methods. Color Key is a trademark of the 3M Company.

color matching

Duplication of the hue, value, and intensity of a given color sample, usually by blending appropriate elements.

color overlap

Slight extension of one printed color over another printed color. In some instances overlap is deliberate in order to compensate for plate-to-plate register inaccuracies. See trap.

color separation

Separation of color artwork into its primary color components through the use of filters (photographic separation) or by electronic scanning. Images are normally separated into the respective process-printing ink colors (yellow, magenta, cyan, and the key color, usually black).

color station

The individual section on a printing press that applies one specific ink color. A printing press will have one color station for each color that it can be called on to print. Also called a deck.

color strength

In printing ink, the effective concentration of coloring material per unit of volume. The higher the coloring strength, the thinner the film that can be printed and the greater the number of sheets resulting per unit volume of ink.

color swatch

A small solid-color print used as a guide in color separation and proofing operations.

color temperature

The color of light expressed in degrees on the Kelvin or absolute temperature scale. The lower the reading, the warmer or redder the light, and the lower the ultraviolet content. As the temperature increases, the green, blue and UV components increase. At about 5,000oK, there is a relatively equal amount of red, green and blue component producing a balanced white light. Graphic arts viewing standards call for color comparisons to be done at 5000oK.

color transparency

A full-color photographic positive image on a transparent support. Usually viewed with the aid of a lighted viewer.

color value

The lightness or darkness of a color. A color may be classified as equivalent to some member of a series of shades ranging from black (the zero-value member) to white. The other two fundamental characterizers of color are hue and saturation.


That portion of an ink formulation that imparts the color. Colorants may be inorganic insoluble pigments, organic dyes, opaque or transparent.


Ability of a pigment in inks, dyes, stains, coatings, and plastics to retain their original hue, chroma, and value under conditions of storage and use. Generally refers to action by light, but when modified, the term may refer to other agents, for example, colorfastness to alkali, to acid, or to ultraviolet light. The permanence of a colored material. Also color retention.


An instrument for quantifying and matching colors. The sample is illuminated by light from three primary-color filters, and scanned by an electronic detecting system. A colorimeter is sometimes used together with a spectrophotometer for close control of color in production. Human observation of color is subject to a great number of variables and influences and, therefore, very subjective.

colors, complementary

A pair of contrasting colors that produce a hue neutral in color and value when mixed in suitable proportions.

colors, contrasting

Two or more colors whose hue, value, or intensity are significantly different from each other.


A proprietary package produced by Combibloc, Inc., Columbus, Ohio, primarily used for the delivery of aseptic juices, dairy product-based drinks, and other beverages. The package is a folding carton laminated from multiple layers of paperboard, polyethylene, aluminum foil, and heat-sealing materials.

Commission Internationale de l’Eclairage

(International Commission on Illumination). An international standards-setting organization for color measurement.


One of two or more monomers that are combined in a polymerization reaction to produce a copolymer.


The ability of a material to resist chemical degradation or physical change caused by the product, or conversely when a container or material does not chemically degrade or physically change the product contained.


An agreement, indication or judgment that the supplier of a product or service has met the requirements of the relevant specifications, contract, or regulation; also the state of meeting the requirements.


(a) A substance containing two or more chemically combined ingredients in its composition. If not chemically combined, the substances are said to be a mixture. (b) A local term applied to a specific material recognized in specific fields. Example: In the manufacture of cans, compound refers to a resilient material used as a gasket to obtain a hermetic seal.

compression strength

The ability of a material or package to resist a force that tends to crush it, measured in newtons or pounds per square inch under specified conditions. Viscoelastic materials such as corrugated board or plastic will have different compression strength test values, depending on how fast the load is applied. Static compression strength usually refers to a container’s ability to withstand a stationary load for a period of time. Dynamic compression strength is the load at failure when an increasing load is rapidly applied.

computer-to-plate (CTP)

The direct digital transfer of an electronic image from the design computer to a printing plate-making device without the need of photographic intermediates. Also direct-to-plate.

computer numerical control (CNC)

Describes the use of a computer or processor on-board the machine to manipulate and instruct the machine in an exact manner.


The amount of substance (weight or percentage) contained in a given quantity of solution; strength.


The process of going from a vapor state to a liquid state such as happens when water vapor condenses into liquid water on a cool surface.


Holding packaging material under controlled conditions so that it attains a specified moisture content and temperature. Preparing packages for test by regulating the moisture content and temperature of the packaging material. Conditioning atmospheres are described in ASTM E 171 and D 618.

conditioning room

A room or chamber in which the temperature and humidity are accurately controlled. Conditioning rooms are used to ensure that all material testing is done under exactly the same conditions. Conditioning rooms may also be used to simulate specific atmospheric conditions for shelf-life testing.


The ability of a material to be bent or shaped around a form without being damaged or marred in any way.


(a) The property of a material that is evidenced by its resistance to flow and its uniformity. Mostly used to describe an ink’s general rheological properties (for example “thick,” “thin,” “buttery”). (b) Resistance of a fluid to deformation. For simple (Newtonian) fluids, the consistency is identical with viscosity; for complex (non-Newtonian) fluids, it’s identical with apparent viscosity.

consumer packaging, consumer package

The unit of retail sale or package that ultimately reaches the consumer. See also consumer unit.

Consumer Product Safety Commission (CPSC)

The federal (U.S.) agency responsible for implementing the Poison Prevention Packaging Act of 1970.

consumer unit

A unit of merchandise in a container that serves as a shelf package in retail outlets.

contact angle

The angle between the edge of a liquid meniscus or drop and the solid surface with which it is in contact. A droplet placed on a horizontal solid surface may remain spherical or spread to a degree that is related to the surface energies of the two materials. The angle between the solid surface and the tangent to the droplet at the curve of contact with the surface is the contact angle. By measuring the droplet contact-angle for water on the subject surface, one may calculate the surface energy (usually expressed in dynes) of the solid. A high contact angle means low wettability. (Reference method: ASTM D 2578.)

contact arc

The number of degrees a flexible web wraps about a cylinder or roll.

contact pressure

The force applied per unit of area to an assembly being united by adhesion. May also be used in other applications to indicate force per unit area.


(a) In general, any receptacle or enclosure for holding a product used in packaging and shipping. (b) Large, reusable enclosures to be filled with smaller packages and discrete objects (as in containerization), to consolidate shipments and allow transport on railway flatcars, flatbed trailers, aircraft, ship’s holds, or as deckloads.


Paper products produced specifically for conversion into corrugated board. The paperboard components (linerboard and corrugating medium) from which corrugated board is manufactured.


The presence of foreign or undesirable substance(s) in a material. Contaminants can be of many varieties: microorganisms, insects and insect parts, moisture, metal, and other foreign or dissimilar materials. Measurement of the contaminant level and acceptable tolerances should be in accordance with current practices for the particular industry or as mutually agreed upon by user and vendor.

continuous-tone image

An image in which the gradation from black to white is continuous. Black-and-white photography is a continuous- tone image.

contract packager/packer

An organization that packages goods for others on contract. Contract packers typically specialize in an area (for example, pharmaceuticals, dry foods, industrial chemicals, and so on)

and maintain a line of versatile equipment that can be assembled into custom filling or packing configurations. May also process the goods in whole or in part.


Describes the difference in the reflected light intensities between the lightest and darkest portion of an image.

contrast modulation

The difference between the darker and the lighter of object or background gray shade divided by the sum of the object gray shade and background gray shade.

contrast ratio

An expression of the ratio between the higher and the lower of object transmittance or background transmittance.


The system governing the starting, stopping, direction of motion, acceleration, speed, retardation, and function of the moving member in a predetermined manner.

control bar

Images printed on the trim edge of printed stock used to control ink densities and print quality. The strip typically contains small solid areas of the inks used, and various overprints and tones.

control chart

A visual record of quality performance in a statistical process that is produced by plotting the value of each sample drawn from the process in graph form with the number of the observation along the horizontal axis and the value of the observation along the vertical axis.

controlled-atmosphere packaging (CAP)

A storage or warehousing technique similar to modified- atmosphere packaging (MAP), controlled-atmosphere packaging extends product shelf life by changing the composition of the surrounding atmosphere from the normal to some other proportion of oxygen, nitrogen, and carbon dioxide. Unlike MAP, CAP involves monitoring the proportion of gases and adjusting them as necessary. For example, the storage of produce at low oxygen concentrations would slowly deplete the oxygen and increase the carbon dioxide component and the relative humidity. In CAP these would periodically be adjusted to maintain a steady-state atmosphere.

controlled substance

A drug that is subject to the Controlled Substances Act of 1970, which sets limitations on its prescription, and requirements for storage and record keeping depending on the potential for physical or psychological dependence.

convenience package

A term suggesting some added benefit that will make the package/product easier to use in some manner. Commonly used in the food industry to identify single service or ready to eat meals.


A manufacturer that takes raw materials and converts them into a usable package or package component. Most commonly used in reference to manufacturers of flexible packaging materials. For example, a converter may print a polypropylene film; combine it with paper, foil, and polyethylene; and slit it to the widths required by a user.


See contract packager.


Any polymer that has been produced from two monomers. More generally, the term is used to describe any polymer that has been produced from more than one monomer.

copolymer, alternating

A copolymer in which two different mer units alternate along the chain in a regular pattern of -A-B-A-B- and so on.

copolymer, block

A copolymer in which the two participating monomers join in alternating blocks or units.

copolymer, random

A copolymer in which the participating monomer units appear in a random order in the molecular chain.


See polymerization.


In general, original graphic material, including art and text, submitted for reproduction. The term also is used to refer to the final printed result. More specifically, in platemaking, copy can be classed as line copy and halftone copy. Line copy is that copy in which the image is composed of solid lines or blocks of color. Halftone copy is that in which the image will appear in varied tones and shades.

copy, distortion

Copy that is intentionally distorted in order to compensate for dimensional changes inherent to the printing process being used or to accommodate processes that will change the material’s shape after the printing is completed. For example, a printing process may increase the image size during transfer to a substrate and the printing plate may need to compensate for this effect. See gain. In plastic film applications, the material may be shrunk or stretched to a new dimension after the material is printed.


(a) A tubular shape around which flexible materials such as plastic film or paper are wound for purposes of transport and handling. (b) The metal body of a roller, which is rubber covered.

core holder

Device for affixing core to shaft.

core plug

Metal, wood, paper, or composite material plugs that are inserted into the cores of rolled webstock to prevent damage to the core during transport and handling.

corona discharge

The flow of electrical energy from a conductor to or through the surrounding air or gas. The phenomenon occurs when the voltage difference is sufficient (> 5,000 V) to cause partial ionization of the gas. The discharge is characterized by a pale violet glow, and the odor of ozone, which forms if the surrounding gas contains oxygen. The ozone can be used to improve adhesive and ink reception by increasing surface polarity. See corona treatment.

corona, treatment

A treatment to alter the surface of plastic and other materials to make them more receptive to adhesives or printing inks. An electrical discharge creates ozone, which in turn oxidizes the substrate surface and creates polar sites that contribute to strong bond formation. The treatment level is measured in dynes. See corona discharge.


The deterioration of a material such as a metal by chemical activity. Corrosion may take place due to the action oxygen (oxidation) or of chemicals such as acids and bases, or to galvanic activity. Rusting is the conversion of iron to iron oxides by reaction with oxygen.

corrosion inhibitor

Any agent, such as oil, plastic, paint, wrapping, or other surface treatment of metal, the primary function of which is to prevent, inhibit, or deter corrosion. May exclude atmosphere by means of a continuous film or may direct corrosion to another sacrificed element. See volatile corrosion inhibitor.

corrugated board

A paperboard assembly consisting of a central member (medium) that has been fluted on a corrugator and to which one or two flat sheets of linerboard have been glued to form single-faced, or singlewall, corrugated board. Doublewall is the combination of two mediums and three facings, and triplewall is the combination of three mediums and four facings. Corrugated board generally is made in one of four flute sizes, designated A, B, C, or E. See also flute.


An alternating ridge and valley or wave-like configuration.


The measure of the surface area covered by an adhesive, coating, or ink. Coverage can be expressed in several ways, for example the amount of applied material required to cover a thousand square feet of web surface. A similar term in metric (the grammage) specifies the mass of material in grams applied to one square metre of web. Coverage can refer to the wet adhesive, coating or ink as applied (see wet mil) or to the dried material.


See poly(ethylene terephthalate), crystallized.


Abbreviation for cost per thousand. The M represents 1000 in Roman numerals.


See Consumer Product Safety Commission.


Excessive impression of plate to substrate or transfer roll to plate, characterized by halo effect or double outline.


A coating imperfection having the appearance of small craters.


The condition where a wet film such as an ink or adhesive does not effectively wet out a surface. The greater affinity for the wet film for itself rather than the substrate causes it to contract into itself, usually forming into compact droplets or beads.


Fine cracks that may extend in a network on or under the surface of or throughout a film layer or adhesive, or on surfaces of glazed materials such as glass, plastics, and painted or enameled surfaces. Also called checking.


(a) (noun) Line or mark made by folding any pliable material, or a similar mark, however produced. (b) (verb) To form a crease in a sheet of any material, usually for the purpose of providing a line along which the sheet can be folded. For example, in the production of folding cartons, paperboard is creased with a creasing or scoring rule in order to provide an accurate line along which the carton can be folded into shape. See score.


The dimensional change or viscous flow of a material under load with time. Unlike elastic deformation, the dimensional change is time dependent and non-recoverable. See cold flow.

crimp, crimp seal

A closure having a corrugated or wavy appearance made by bringing two webs together and sealing, most commonly using heat-seal methods.


Smudging, or rubbing off of ink.


Trade name for off-press color proofs using DuPont materials. Composed of four film layers that simulate the four process colors, bound together into a single page, Cromalins are used to check the positioning of the graphic elements and approximate colors. Cromalins have largely been replaced by Waterproofs (See Waterproof) and both of these analog methods will eventually be phased out in favor of digital proofing methods.


Trimming off unwanted areas of an illustration, photo, or other design element.

crop mark

Marks made on the outer edges of artwork to designate the area to be printed.


A laminate in which the grain direction of two plies are at right angles to each other.


A polymer in which individual molecular chains are linked by side branches to adjacent chains. Cross-linking may be present to varying degrees. A heavily cross-linked polymer is classed as a thermoset plastic.

cross-linking, radiation

The formation of chemical links between polymer chains through the action of high-energy radiation, commonly gamma radiation from a cobalt-60 source or electrons from an electron gun. The treatment improves the modulus and boosts the use temperature of some polymer films. Exposure must be accurately controlled if the cross-linking is to be achieved without degrading the resin. See irradiation and radiation, gamma.

cross direction (CD)

The direction at right angles to a material’s flow through a machine. Flow direction through a machine may impart directional properties to a material. For example, paper acquires directionality during manufacture known as cross direction (perpendicular to the paper flow through the machine) and machine direction (parallel to the paper flow). Also referred to as transverse direction, cross grain, and cross web.

cross grain

See cross direction.

cross mark

See register mark.

cross seal

The horizontal or cross machine-direction seal made on a vertical form-fill-seal machine.


Difference in diameter between the center of the roll and reference points at or near the ends of the roll face, generally with center of the roll larger in diameter than the ends.


A homogeneous solid having an orderly and repetitive three- dimensional arrangement of its atoms. Opposite of amorphous, where molecule position is random.


The formation of regular molecular patterns within a mass of material. Crystallization will affect material physical properties and sometimes appearance. Degrees of crystallinity are particularly important to polymer properties.


Slightly upturned edges on the image areas of a flexographic printing plate. The higher edges will produce an inconsistent ink distribution on the printed substrate.


Curing implies a chemical change as compared to drying which indicates a loss of solvent. (a) To treat a material by the application of time, heat, pressure, catalysts, chemical agents, or combinations of these, to initiate the desired chemical changes. (b) In adhesives, to change the physical properties of an adhesive by chemical reaction, which may be chemical condensation, polymerization, or cross-linking; usually accomplished by the action of heat and catalyst, either alone or in combination.

curing temperature

The temperature to which an ink, coating, adhesive, or an assembly is subjected to cure the material.

curing time

In adhesion, the period of time during which an assembly is subjected to heat, pressure, or both to cure the adhesive.

curing, radio-frequency

The process by which a radio frequency is used to impart heat. Also called dielectric heating.


Deformation of a paper sheet that tends to roll it into a cylindrical form. Curl is caused by inequalities in hygroreactivity or stress levels between the two sides of the sheet. Contributing factors include differences between the two sides in fiber orientation, pigmentation, sizing, applied coatings, laminations and drying conditions. The greatest curl level is usually observed when the paper is in relative humidity conditions that are different than the relative humidity that is in equilibrium with the moisture content of the paper as made.

curtain coating

A method of applying a coating to a material where the material is passed through a free-falling curtain or film of the fluid coating.

curve direction

The direction of web travel on a flexo press.


A soft resilient material generally used to protect products by absorbing shock inputs such as might be encountered when the product is dropped.

cushion stickyback

See blanket, compressible.


To dilute or thin an adhesive, ink, varnish, or other material with a solvent or water.



A Du Pont trademark for a photopolymer platemaking material most commonly used to produce flexographic printing plates.


A distortion of the form or shape of an article.

deformation under load

(a) Change in dimensions or shape of a material when subjected to external forces. (b) When applied to plastics may refer to deformation due to cold flow. See cold flow.


A change in a material’s chemical structure. For most applications, degradation is undesirable. However, in instances such as environmental issues, degradation may be a positive attribute.

degradation, ultraviolet

Ultraviolet (UV) radiation has enough energy to initiate and/ or accelerate certain chemical reactions. These can result in degradation of packaging material or product. UV radiation is present in some light sources, but particularly in sunlight. The most damaging wavelengths are the longer UV emissions. Many plastics are subject to UV initiated degradation, typically observed as crazing, chalking, discoloration, fading, loss of strength, or embrittlement. Many foods and pharmaceuticals are detrimentally affected by UV light. In many instances the UV radiation initiates and accelerates oxidation reactions.

degree of polymerization

The average number of monomer units or mers in a given polymer. For most plastic materials, this number must reach several thousand before useful physical properties are realized.


To dry out or remove moisture from the air by means of dehumidifiers, ventilating, or by using a desiccant.


The process of removing printing inks from recovered paper waste during recycling. Most inks used for printing packaging materials are thermosets and are therefore difficult to remove. Newsprint inks are relatively easy to remove.


Separation or splitting of laminate layers caused by lack of adhesive, inadequate adhesion, or by mechanical disruption.


The process of turning an active electronic article surveillance (EAS) tag by contact or noncontact means to an inactive state.

deadfold, dead fold

A material’s ability to remain in place when folded or creased. Aluminum and paper are described as having good deadfold properties. With few exceptions, most plastics have poor deadfold properties.


Impressing a portion of a material below the initial surface level to form a decoration. Sometimes the background, rather than the lettering itself, is debossed, leaving the decoration at the original level of the material, thus giving the appearance of embossing. Opposite of emboss.


A term used mostly in flexographic printing to describe a single print station with an ink fountain, inking or anilox roll, printing plate, and impression cylinder.


The edges of a web.


Breakdown of molecular structure by chemical or thermal action. With polymers, depending on the severity of conditions, decomposition products can range from sub-polymers and oligomers down to monomers and individual atoms.


Printing, stamping, embossing and other treatments used to produce a wide variety of colors, shapes, effects and designs for the purpose of creating aesthetic and informational appeal.


A quality characteristic that will detrimentally affect the required performance or appearance of the package, material, or component.


A dimensional change in the testing direction between an established preload and the ultimate failure load during compression, tensile and flexural testing.

deliquescent, deliquescence

A form of hygroscopicity. That property which causes a material to absorb enough atmospheric moisture to dissolve or liquefy itself. See hygroscopic.


A specified product or service that is defined in a contractual agreement and must be delivered to the customer in order to fulfill the terms of the contract.

delivery end

That end of a machine or production line from which the finished product emerges.


An instrument that measures the light reflected from surface. Colors are read as optical or tonal density. It is used to check the uniformity of print color.


The reversion of a polymer to a polymer of lower molecular weight or eventually its monomer. Reversion occurs in most plastics when they are exposed to very high temperatures in the absence of air.


(a) The distance from the top to the bottom of an engraved cell on an anilox or gravure roll. (b) The intensity of a hue or shade of color.


A substance having a high affinity for water vapor and therefore able to absorb it from surrounding atmospheres. Desiccants are used to control the humidity level in sealed packages. Commonly used desiccants include activated silica gel and calcium chloride.

desiccant pouch

A pouch or sachet containing a desiccant substance. See desiccant.

desiccant, activated

An adsorptive desiccant that has been treated by heating and

ventilating or by other means to develop internal surfaces on which moisture and certain vapors or gases will collect.

design brief

A package design brief is a comprehensive project-planning document detailing what a proposed package design is supposed to achieve; in what marketplace, with what customers, by what means, and in conjunction with what other activities. The design brief has a full, detailed description of the objectives developed for the project.


The capability of identifying merchandise that is tagged with an active electronic article surveillance (EAS) tag.

detection zone

That area within which the detector’s signal is strong enough to identify an active electronic article surveillance (EAS) tag. Also known as the pedestal width.


(a) Any device whose purpose is to register the presence or absence of some selected feature as for example a metal detector or fill level detector. (b) A device for detecting the presence of an active electronic article surveillance (EAS) tag. EAS detectors are typically installed at retail store exits as a means for detecting stolen merchandise.

detector, metal

A device that can detect metal contamination within a product or package and reject those found to be contaminated.


The loss of quality, appearance, physical attributes or usefulness of an item; degradation.


Any of various soluble, tacky substances (polysaccharides) obtained from starch by the action of heat, acids, or enzymes. Dextrins are used as packaging adhesives though their use is declining in favor of faster setting emulsions and hot melt adhesives.


(a) Generally a forming device that forms a material in two axis as compared to a mold which forms shapes in three axis. (b) Any of various sharp cutting forms, rotary or flat, used to cut shapes from paper, paperboard, or other sheet stock. For example, a steel-rule cutting die is used to cut paper or paperboard shapes from a press sheet (c) A device to give form to an extruded plastic material.


(a) Any operation in which a form that incorporates sharp cutting edges is pressed onto a substrate to cut out a designed shape. For example, the cutting of paperboard,

plastic or other material by the sharpened edge of a thin strip of steel rule mounted vertically on a wood frame (the die). (b) Having been shaped, cut, blanked, punched (for holes), etc., in a die-cutting operation.

die line, die-line

A computer-generated layout of the intended die-cut shape on a clear dimensionally stable material such as acetate or polyester. See die sheet.

dielectric heating, sealing

The process of heating a plastic by using it as the dielectric of a condenser to which a high frequency voltage is applied. The process has particular application for heat sealing vinyl films. See heating, dielectric.

die sheet

An accurate record of a package’s geometric shape and features for use by the package designers to enable them to secure register accuracy in the art work. The die sheet, typically an outline drawn onto a clear dimensionally stable plastic sheet, shows the functional design of the package, within the confines of which the package designer must fit the artwork. See also die lines.


(a) Drug identification number. An approval and record- keeping number issued in Canada by Health Protection Branch, which identifies a drug and its packaging. The DIN number must appear on all pharmaceutical packaging. Equivalent to the American National Drug Code (NDC) number. (b) Acronym for Deutsches Institute fuer Normung (The German Standards Organization) and its standards.

DIN cup

An efflux type cup device for measuring viscosity that conforms to German DIN standards. See efflux cup.

direct printing

Any printing process where the ink is transferred directly from the image carrier (plate) to the substrate being printed as compared to offset processes where the ink is transferred to an intermediate or blanket roll before application to the substrate.

direct-to-press (DTP)

The imposition of the print image directly onto an image carrier already mounted in the printing press. Digital information is sent directly to printing stations in the press, eliminating mounting and register time. Also computer-to-press.


Any change from the original color, most commonly caused by outside influences such as light exposure, irradiation, chemical exposure, or excessive heat.


A lack of continuity or cohesion; an interruption in the normal physical structure of a material or a product.


The degree to which a vision system is capable of sensing differences in light intensity between two regions.

dishing (of rollstock)

Slight misalignments during slitting and winding of films or laminates can cause the wound product to move incrementally in an axial direction producing a dished appearance at one end and a corresponding cone-shape at the opposite end of the roll.


The breaking down or deterioration of a material. Deterioration usually implies changes in the material’s chemical structure.


A device that permits distribution or serving of a product in convenient form and quantity.

The component of reflected light that radiates in all directions from the reflecting surface.


A spreading out or equalized dispersion of material, force, or condition into the surrounding medium; as, the diffusion of heat by conduction; the diffusion of light through a translucent material or reflection from a rough surface; the diffusion of gases, liquids, or granular solids into the surrounding medium.

digital prepress

The process of producing printing plates using digital information rather than analog (mechanical) photographic films.


A computer peripheral device that converts an analog signal into a digital signal.


The viscosity of a dilatant liquid increases as agitation is increased at constant temperature.


An economical solvent of lesser dissolving power used to dilute a more costly primary solvent with only a slight reduction in the solvent power of the primary solvent. See also extender.

dimensional stability

The property of having little or no change in dimension when exposed to changes in temperature and humidity.

dispensing edge

On a pressure-sensitive label dispenser, the sharp edge around which the backing material is pulled in order to separate the label from the backing and present it to the surface to be labeled.


A uniform distribution of solid particles in a liquid vehicle. For example, printing inks are dispersions of colored pigment particles in a liquid vehicle that is capable of being solidified.


The point of maximum density in an image.


The point of minimum density in an image.


To treat a material in some way, such as adding elements to a mixture, for example, to doctor an ink.

doctor blade

A knife-like bar that is used to regulate the amount or thickness of adhesive, coating, or ink being applied to a surface by controlled wiping. For example, on a gravure roll, the doctor blade removes all the ink from the roll surface, leaving only the ink residing in the cells. See also doctor.

doctor roll

(a) A roll used on a glue spreader or other coating machine to regulate the amount of material fed to a spreader roll. (b) A rubber-covered roll having a wiping action that leaves a thin regulated film of ink on the surface of an anilox roll.


Text describing a process, program, or system so that anyone using them can see what has to be done to produce a desired result, as well as what has to be done in order to maintain the process, program, or system.

dot growth

See dot gain.

dot skip

See skip.

dot, elliptical

Elongated dots in halftone images that give improved gradation of tones particularly in middle tones and vignettes. Also called chain dots.

double package maker (DPM)

A packaging machine that forms an inner liner and an outside package in one operation. One of the more common applications is for the production of cereal packaging where the cereal is contained in a flexible pouch placed in a folding carton.


In printing, a screen dot that has printed only the outside perimeter leaving the center unlinked.


Reducing the thickness of a flexible packaging material.


The original name for a gusseted-bottom stand-up pouch patented by the Doyen family (France 1963). The pouch generated little commercial interest until the late 1980s.


An acronym for dots per inch. Also referred to as lines per inch (LPI). See screen.


Thinning in gauge or narrowing in width of a sheet by tension in windup.


A bead of excessive ink appearing at the trailing edge of a print.

draw-down, drawdown

A swatch of color or coating made by spreading a small amount of ink or varnish across a sheet of material. Made for visual analysis, for example, when trying to match an ink formulation to a PMS standard color chip on the actual material to be printed. Also color swatch.


(a) A substance added to inks or varnishes to accelerate drying or solidification. In most formulations, the drier accelerates oxidation processes. (b) An oven-like unit as would be found on a printing or coating and laminating machine whose purpose is to remove volatiles such as solvent or water. Drying usually is accomplished with heat, although ambient temperature forced-air systems occasionally are used. Also spelled dryer.


(a) A change in the hue or shade of a color. (b) Change in a


A slang term used in reference to a coating or an adhesive.


A single image element as would be found in a halftone image. The dots in a halftone will have equal spacing designated as the screen, but will vary in area to produce different tints. The dot can be round, elliptical, square or other shape. A more recent technology (stochastic printing) uses very small dots of identical size but varies the density of dot placement. Each treatment has its strengths and limitations. See screen, dot.

dot gain

In printing, the increase in dot size inherent in the transfer of ink to a substrate. Normally measured as a percentage increase. Flexography, in particular, has significant gain from the design dot size. Gain can cause process colors to be inconsistent and can fill in universal product codes and make them unreliable. Sometimes termed dot growth.


The deviation of a packaging film from sheet flatness.


Removing a color from behind another color so that the first color does not affect the appearance of the second color.

drug master file (DMF)

A confidential file maintained by the Food and Drug Administration on the construction of proven and approved pharmaceutical packaging systems. New submissions for packaging approval can be compared with the DMF to help accelerate new approvals.

dry strength

The strength of an adhesive joint measured after drying under specified conditions or after a period of conditioning in the standard laboratory atmosphere.


An oven or chamber that through heat and air circulation removes volatiles from adhesives, coatings and inks. Alternate spelling of drier.


The removal of volatile components such as water or solvent from a material. In the instance of materials such as inks and adhesives, drying changes the material from a liquid form to a solid.

drying rate

The rate at which volatile components such as water or solvent are removed from a material. Drying rate affects the time where the material in question can be further processed. For example, the drying time of a printed ink film is the elapsed time from the moment of impression until the film has reached a satisfactory degree of resistance to smudging.

drying temperature

The temperature to which an ink, adhesive or coating on a substrate or in an assembly is subjected in order to dry the material.

drying time

The time required for an applied fluid substance, such as adhesive, ink, or coating, to lose enough of its volatile material content to be suitable for further processing or its intended function.

drying, infrared

Drying of printing inks by the use of infrared radiation as a heat energy source.


See Duales System Deutschland.


See direct-to-press.


Packaging materials that can be used in both microwave and conventional ovens. Among the commonly used materials are: ovenable paperboard, and heat-stable plastics such as crystallized polyester (CPET) and nylon.

Duales System Deutschland(DSD)

The industry-supported system for recycling and waste management in Germany.


An image produced from two colored halftones.


A measure of rubber or plastic hardness, usually made with a Shore “A” durometer gauge. Commonly used to express the hardness of flexographic printing plates. (Reference method: ASTM D 2240.)


The time interval during which elements remain in contact or in a static position; a pause.


Synthetic or natural organic coloring material that is soluble in an ink vehicle, as compared to a pigment, which is not soluble and must be dispersed.

dynamic coefficient of friction

See coefficient of friction.


In the (now deprecated) cgs system of units, the force required to accelerate a mass of 1 gram by 1 centimetre per second2. (1 dyne = 1 x 10-5 newton). In packaging, used as a measure of surface energy or polarity of a surface. The dyne level is an indicator of the ability to wet out the surface with a liquid, and is related forming a chemical bond with an adhesive, coating, or ink. The dyne level of a surface typically needs to be 37 or higher, depending on the nature of the adhesive substance.(Reference method: ASTMD2578.)

dyne solutions

Solutions of known dyne levels prepared by mixing different proportions of formamide and cellosolve. The dyne level of a surface is determined by finding the solution that just wets (does not bead up) the material surface. For good ink or adhesive bonding, the dyne level of the material surface should be at least 10 units higher than the dyne level of the ink. (Reference test method ASTM D2578.)


Acronym for ethylene-acrylic acid.


See European Article Numbering.

ear, ears

The ear-like extensions that appear at the corner of sacks after they are filled and closed, principally found on flat tube sacks.


See electronic article surveillance.

EAS tag/label

See tag, electronic article surveillance (EAS).


See electron beam.


Off-center or out-of-round condition, such as a roll or cylinder that does not rotate in a true concentric circle in relation to its axis.

edge lift

When the edge or corner of a label lifts from the labeled surface. Edge lift is dependent on adhesive strength, stiffness of the label stock, and the diameter of the object being labeled.


See ethylene-ethyl acrylate.

efflux cup

A viscometer consisting of a cup having a calibrated hole in the bottom. Viscosity is quantified by the number of seconds required for a specified volume to flow out of the cup. DIN, Zahn and Shell cups are variations of efflux-type viscosity measuring systems. See also viscosity and Brookfield viscometer.

elastic deformation

A change in dimensions of an object under load that is fully recovered when the load is released. Unlike viscous flow deformation, elastic deformation is not time dependent.

elastic limit

The greatest stress that a material can experience which, when released, will result in no permanent deformation. The point at which a material exceeds its elastic limit is the yield point.


The ability of a material to quickly recover its original dimensions after removal of a load that has caused deformation.


A material that has high elongation properties, most commonly defined as being able to be stretched more than twice

its original length and being able to return to its original length when the stress is released. Most packaging elastomers are synthetic polymers, except for natural rubber.


Flexible and resilient. Capable of being elongated and able to return to its original dimension. See elastomer and elongation.

electric eye

An electronic photocell device that responds to the presence of light. Used for a variety of machine control applications.

electron beam (EB)

A flow of accelerated electrons similar to that used in television screens excepting at a much higher energy level. Electron beam energy is used to cure inks, coatings and adhesives. Also used to introduce levels of cross-linking to plastics and for material sterilization.

electronic article surveillance (EAS)

A system of deterring pilferage by making merchandise detectable by electronic sensing systems. EAS tags merchandise with devices that, unless deactivated, can be detected by magnetic or radio frequency means as the tagged article passes through a sensing zone. Also called electronic surveillance packaging (ESP). See tag, electronic article surveillance.

electronic surveillance packaging

Sometimes referred to by acronym ESP. See electronic article surveillance.

electrostatic assist

The use in rotogravure printing of an applied electrical charge difference between the substrate being printed and the gravure cylinder to improve ink transfer.

electrostatic discharge (ESD)

The transfer of static electrical charges between bodies of different electrostatic potentials. See also static dissipative agent.

electrostatic shielding packaging

Materials capable of attenuating an electrostatic field so that its effects do not reach the packaged item. A form of protective packaging that is used for solid-state electronic devices to prevent damage caused by electrostatic discharges, electrostatic fields, and triboelectric charge generation. Commonly referred to as ant-static packaging but more correctly static dissipative packaging. See static dissipative material.

Elmendorf tear test

See test, Elmendorf.


The difference in length, expressed as a percentage of the original length or in units per unit length, such as inches per foot or millimetres per metre, when a specimen is subjected to a tensile load. For plastic packaging materials, elongation at yield is the elongation at the point at which the specimen will not return to its original dimensions. Elongation at break, or ultimate elongation, is the elongation at fracture.

emboss, embossing

(a) Any of several techniques used to create raised patterns in sheet packaging materials. Paper and paperboards are embossed by passing them through embossing rolls, or pressing them between suitably shaped plates. (b) Raised design or lettering made by embossing the surface of a material or object. See debossing.

environmental stress crack resistance (ESCR)

A fracture in a molded plastic component resulting from realignment of polymer molecules, particularly those in high- stress areas. Stress cracking is a physical phenomenon and is not related to chemical compatibility. However, certain agents, such as surfactants, are known to accelerate or contribute to stress cracking, even though they themselves do not chemically react with the plastic. (Reference test method: ASTM D 2561.)


See Environmental Protection Agency.


Polymers made by the reaction of epoxides or oxiranes with other materials such as amines, alcohols, phenols, carboxylic acids, acid anhydrides, and unsaturated compounds. Epoxies are used to make adhesives and various protective coatings for the packaging industry.


See extended producer responsibility.


See polystyrene, expanded.


A point at which a substance neither gains nor loses a stated property or condition. For example, paper when it is at equilibrium with the ambient relative humidity will neither lose or gain moisture and in doing so will not change in its physical properties.


The value, trust, or recognition given to a product or company based on a long-standing satisfaction with the product or company.


See relative humidity, equilibrium.


See electrostatic discharge.

essential oil

A generic term for relatively volatile liquids, whose vapors can be detected by the sense of smell. Essential oils are used in many health and beauty aid products to produce pleasant aromas and in foods are critical to our sense of flavor. (smell plus taste is flavor). Because they are volatile, they can be easily lost and therefore require some level of barrier packaging.


The reaction product of an acid and an alcohol. Reaction of simple acids and alcohols produces a line of solvents (acetates) such as ethyl acetate and isopropyl acetate. More complex multifunctional acids and alcohols are able to form polymer chains (polyesters). Poly(ethylene terephthalate), a common packaging polymer, is produced by reacting terephthalic acid and ethylene glycol.


A condition on an offset printing press where ink and fountain solutions are intermixed on ink rollers.


A homogenous mixture of two or more materials that are not normally miscible. Emulsions depend on the action of an additional material usually referred to as the emulsifying agent. For example, oil and water, two immiscible materials, can be emulsified by the addition of a wetting agent such as a detergent to act as the emulsifier. Compare to a true solution where one substance dissolves in another without the help of additives.


A general term for a class of coatings that dry or oxidize to a high gloss finish.

energy, surface

See surface tension.


To cut or etch an image into a hard surface using a mechanical tool, chemicals, or laser.


A pattern that has been manually cut, mechanically incised, or chemically etched into a surface. For example, gravure printing cylinders and Anilox rolls are said to be engraved.


(a) A flexible material (most commonly paper) construct having only two faces, and joined at three edges to form an enclosure. The non-joined edge provides a filling opening, which may later be closed by a gummed or adhesive flap, heat seal, tie string, metal clasp, or other method. Terms such as pouch or sachet are usually used to describe similar flexible plastic or laminate constructs. (b) Loosely, any wrapper or covering which envelopes.

envelope, gusset

An envelope that incorporates pleats to permit expansion and thus greater enclosed volume.

environmental chamber

A chamber or enclosure used to create ranges of temperature and humidity. Environmental chambers are used to simulate use conditions, usually for the purpose of accelerated testing of packages and products.

Environmental Protection Agency

U.S. government agency. Also may refer to state or municipal organizations.


The sum total of the visual response to the appearance of an object or package. Elements of esthetics may include: color, shape, graphic, texture or other particular features of the package.

etch, etching

(a) The process of producing a design on a metal plate by causing lines to be eaten in by corrosive substance, or cut by a sharp point (dry-point stylus). (b) The design produced on an etched plate. (c) A mild degree of surface corrosion, particularly on a highly polished surface.


Any of a class of organic compounds where two functional groups (radicals) are directly attached to a single oxygen molecule.

ethyl cellulose

A cellulose ether polymeric material derived from cellulose. Ethyl cellulose is readily soluble in most organic solvents and can be cast into a transparent film. Commonly used as an ingredient in inks and coatings.

ethylene acrylic acid (EAA)

EAA is a copolymer of ethylene and acrylic acid. Its ionic nature allows for excellent adhesive bonding to metal foil and other polar surfaces. EAA’s adhesive and toughness qualities is taken advantage of in high performance multi-layer laminates.

ethylene-ethyl acrylate (EEA)

The copolymerization of ethylene with ethyl acrylate produces an ethylene acid copolymer. The polymers are produced with varying percentages of acrylate content, most typically between 15 and 30%. EEA is compatible with all olefin polymers and often is blended with these to modify properties. EEA is used in hot-melt formulations. It also can be used alone or as a component of heat-sealable coatings where it offers improved toughness at low temperatures, excellent adhesion to nonpolar substrates, and a broad service temperature range. EEA is used as a tie layer between mating laminate films. EEA produces a very tough, clear film, often used directly as a product wrap.

ethylene-methyl acrylate (EMAC)

The copolymerization of ethylene with methyl acrylate produces an ethylene copolymer, one of the most thermally stable of the olefin copolymers. The polymers are produced with varying percentages of methyl acrylate content, most typically between 18 and 24% of the structure. Alone or in blends, it has found applications in film, extrusion coating, sheet, laminating, and coextrusion. Ethylene-methyl acrylate’s heat stability make it a good choice for many heat-sealing applications including radio-frequency sealing. It meets food packaging requirements and is approved for use as a food- contacting heat-seal surface in aseptic packaging where hydrogen peroxide sanitizing solution is used.

ethylene oxide

A gas used for sterilization of healthcare products. Packages must be porous to allow the gas to penetrate into and around the contained product. One advantage is that the process is done at comparatively low temperatures; typically about 60oC (140oF).

ethylene(vinyl acetate) (EVA)

A polar copolymer of ethylene and vinyl acetate, retaining some of the properties of polyethylene but with increased flexibility, elongation, and impact resistance. Copolymers containing less than 5% vinyl acetate are defined as polyethylene or modified polyethylene. Above 50% vinyl acetate, they are considered vinyl acetate-ethylene (VAE) copolymers. The addition of vinyl acetate reduces polymer crystallinity, which increases flexibility and reduces stiffness. The combination of high clarity, puncture resistance, impact strength, and low heat-seal temperature makes EVA useful for many flexible packaging applications such as shrink wrap, heavy- duty shipping sacks, produce bags, ice bags, and bag-in-box applications. EVA is frequently specified as the extrusion coating on polypropylene, poly(ethylene terephthalate), and aluminum foil to provide good heat-seals at high converting rates, or as the adhesive layer in some laminates. EVA is the base or backbone polymer of many hot-melt adhesive formulations. EVA is used to make color concentrates for plastics processing on account of its ability to wet-out pigments.

ethylene(vinyl alcohol) (EVOH)

Can be regarded as a copolymer of polyethylene to which varying amounts of the -OH functional group have been added. A typical packaging EVOH is about 20 to 35% ethylene. EVOH is one of the best polymeric oxygen barriers available to packagers. However, its susceptibility to water requires that for most applications it be laminated or coextruded into a protective sandwich with materials that will keep the EVOH layer away from water. The abbreviation EVAL refers to EVOH made by EVAL Co. of America, Lisle, Illinois.

European Article Numbering (EAN)

The standard machine-readable bar code system that is used in Europe for retail food packages. A system equivalent to the Universal Product Code (UPC) used in North America.


See ethylene(vinyl acetate).


See ethylene(vinyl alcohol).


The change from a liquid state to a gaseous state, as when a liquid boils or a solvent leaves a base formulation such as an ink or an adhesive.


A chemical reaction that produces heat.


A change in dimension such as might be caused by a change in temperature or moisture content.


Equipment designed to operate in environments that pose a possible explosion hazard if a source of ignition is present, for example, highly flammable solvent or dust concentrations. For the most part, explosion-proofing addresses electrical equipment and concerns the sealing or design of switching and electrical circuits to eliminate or isolate any possible source of electrical sparks. Mechanical devices in such a location usually are described as nonsparking rather than explosion-proof.

explosion limit, lower (LEL)

Lower explosion limit; the lowest concentration of combustible vapor in air that will explode.


(a) In photography and the manufacture of printing plates, to subject a photosensitive film, printing plate, or other photo- sensitive material to the action of light. Areas exposed to light change chemically, allowing them to be differentiated from the unexposed areas. (b) exposure: The step in photographic processes during which light produces the image on the light- sensitive coating.

Extended producer responsibility (EPR)

A waste management position proposing that the producer is responsible for properly disposing of all packaging used with their product. EPR in various forms is being incorporated in the policies and laws of a growing number of countries.


A substance, such as a pigment, low-cost polymer, or an inert ingredient, which is added to formulations such as adhesives or inks, to increase the bulk in relation to the active or primary ingredient. Extender substances primarily reduce the amount of more costly primary ingredients present in a formulation. Solvent extenders are more usually known as diluents.


(a) A material that is capable of being stretched under normal processing conditions. (b) Extensibility:The ability of a material to stretch or elongate when tensile stress is applied. It is expressed as a percentage of the original length. Ultimate elongation is the stress just prior to specimen rupture.


The plastic material delivered by an extruder.

extruded film

Generally used to describe film made by the cast extrusion method.


A machine having a screw device rotating inside a strong steel barrel. Polymer pellets are fed into a hopper in one end, and the action of the screw, supplemented by heating elements, melts and fluidizes the polymer feedstock. The melt, at a consistent temperature, is then ready to be ejected into

whatever die, mold, or other forming device will be used to shape the plastic.

extruder barrel

In the extrusion of plastics such as would be found in the production of plastic films, the hollow cylinder in which the plastic material is gradually heated and melted and from which it is extruded. Inside is a helical screw, which compresses and moves the plastic from one end of the barrel to the other in the course of melting the plastic.


The process of forming a thermoplastic film, or profile by forcing the polymer melt through a shaped die or orifice followed by immediate chilling. Profile extrusion produces continuous lengths of constant cross section. See film, blown and film, cast.

extrusion blown film

The continuous manufacture of thin film by extruding and then inflating a bubble of molten resin. See film, blown.

extrusion cast film

Film made by extruding a thin curtain of thermoplastic melt onto a highly polished chilled drum. After the film solidifies, it is edge trimmed and wound into rolls for further processing.

extrusion lamination

See lamination, extrusion.

extrusion plasticizing system

See extruder and extrusion.

extrusion plastometer

A type of viscometer consisting of a vertical bore inside a heated jacket. The bore is fitted with a close-fitting weighted piston, and the end of the bore has a calibrated orifice. Polymer pellets are loaded into the bore, brought to the test temperature and the piston is released. The melt-flow rate (MFR) is reported as the grams extruded in 10 minutes. Different temperatures and piston weights are specified for different plastics, and it is important to state test conditions. MFR is a crude indicator of molecular weight. Determination of MFR is described in ASTM D 1238. See melt flow rate.

extrusion, sheet

The manufacture of plastic sheet by extruding a curtain of the plastic melt onto chill rolls.


Migration of an ingredient in a material or product to the surface. See plasticizer migration.

eye mark

A machine-recognizable mark, printed on web-fed packaging materials. The eye mark is the reference point from which the machine will register other operations such as further decoration, heat-sealing, or package cutoff.

eye spot

See eye mark.


A small hole in a tag to receive a string or clasp. May be plain or reinforced with a metal ring, or paper or cloth backing. Also called a grommet.


Any one of the plane surfaces of a container. In a paper or film bag, the side opposite the side seam.

face material

The material that is (usually) decorated and becomes the label portion of a pressure-sensitive label system after bonding to a suitable backing or carrier material. Also facing material, facestock.


An instrument for determining the resistance of materials to fading. This apparatus accelerates the fading by subjecting the material to high intensity ultraviolet rays of approximately the same wavelength as those found in sunlight. Fade-Ometer is the trademark of a particular device.


Loss of color brilliance caused by exposure to light, heat, or other agent.

failure analysis

A formal analysis that attempts to define the paths leading to failure and what should be done to prevent it.

failure, fatigue

The failure that occurs as a result of a number of repetitions of a load as opposed to creep which is a failure caused by the continuous application of a load.

false body

A thixotropic flow property of a fluid. Thixotropic materials at rest can have an increase in apparent viscosity, or have the appearance of a semi-solid that may lead to the conclusion that they have partly dried. Stirring the product will return the product to a more fluid state.

family pack

A nonspecific term that may indicate a larger package in a range of sizes. Alternately, a collection or group of individual packages consolidated into a single unit as, for example, a variety of unit-sized breakfast cereal cartons sold as one unit.


A continuous web of labelstock that is not cut into individual units or wound into a roll form, but rather folded at regular intervals into a zig-zag pattern.

fast color

A colored material that retains its color under the influence of aging, light, heat, etc., and does not bleed. See colorfast.


(a) Resistance of a stock or color to change due to environmental conditions. (b) The stability or resistance of pigments to influences such as light, alkali, etc. The best of these are known as fast reds, fast blues, etc.

fast solvent

A highly volatile organic solvent.


A term used to describe a paper or other material that does not discolor when in contact with alkaline materials.


A term used to describe a material that is not significantly discolored by exposure to light.


See Food and Drug Administration.


In printing, irregular or ragged patterns that develop at the edges of lines or solids. Feathering might result if a fluid ink is applied to a very porous paper or board.


A material take-up and release system found on web-fed converting or processing machines. Festoons store material so that downstream operations can continue for a short period while upstream operations are slowed or stopped. For example, a festoon would supply pouch stock material for the short time it takes to insert a fresh roll of material. Festoons also might be used ahead of an intermittent-motion step in an otherwise continuous-motion process. See rolls, dancer.


See form-fill-seal.


Acronym for the Foundation of the Flexographic Technical Association.


Generally used to describe the tough kraft-based paperboard used in the manufacture of corrugated boxes. Also heavy fiber sheets that have been produced or laminated to a thickness that provides a high degree of stiffness.

fiber tear bond

In a paper-based lamination or adhesive bond, the tearing of fibers rather than a delamination when the bond is pulled apart.

fiber optics

A light source for vision systems by which light is transmitted through a long flexible fiber of transparent material through by internal reflection.


(a) The distortion or lack of sharpness seen in heavy tones (75% and upward) caused by the filling in of the voids between dots in the tone area. This effect can be caused by paper, ink, or improper printing technique, such as excessive amounts of ink or printing pressure. (b) The filling in of the open portions of small type and graphic elements with ink.


(a) The inner ply or plies of a multi-ply paperboard sheet, usually composed of lesser quality fiber. (b) A material or form whose purpose is to occupy space or fill a void. (c) A machine or device whose purpose is to place product into a package.


(a) Filling a package to a specified level. (b) Net weight filling a package with a specific, measurable weight of product. (c) Volumetric filling of a package with a specific, measurable volume of product. (d) A printing defect where the voids in the printing plates are filled with ink.

filling, aseptic

A process where product is sterilized before the filling point and filled under sterile conditions into a previously sterilized container. See also aseptic packaging.


Generally used to describe a thin plastic material usually not more than 76 micrometres (0.003 inch) thick. Above this, thin materials are usually referred to as “sheet.”

film, antifog, film antifogging

A packaging film used for such products as fresh produce, that has been treated so that moisture droplets do not accumulate on the inner surface.

film, biaxially oriented

A film in which the molecular structure is highly oriented in both machine and cross (transverse) directions to improve various physical and barrier properties.

film, blown

The manufacture of thermoplastic film where an extruded plastic tube is continuously inflated by internal air pressure, cooled, collapsed flat rolls, and subsequently wound into rolls. The tube is usually extruded vertically upward, and air is admitted through a passage in the center of the die as the molten tube emerges from the die. An air ring provides air flow around the outside of the bubble to increase initial cooling close to the die. Air is contained within the blown bubble by a pair of pinch rolls, which also serve to collapse and flatten the film. Film thickness is controlled by the die-lip opening, by varying bubble air pressure, and by the extrusion and take-off rate. Thin films with considerable biaxial orientation can be produced by this method.

film, breathable

A film having significant gas permeability. This can be due to the inherent properties of the film material, the presence of open cells throughout its mass, or to minute perforations.

film, calendered

A film manufactured between rollers on a calendering machine, as distinguished from films that are cast or blown.

film, cast

Film made by extruding a thin curtain of thermoplastic melt onto a highly polished chilled drum. After the film solidifies, it is edge trimmed and wound into rolls for further processing.

film, cavitated

A plastic film produced with minute voids that results in an opaque material. Cavitated materials such as polypropylene are used as labelstock and as wrap material for situations where paper would not be suitable.

film, centerfold

A film that is delivered folded along its length, mostly used in L-bar heat sealers.

film, cross-linked

Term applied to polymer film that has been irradiated or chemically processed to cross-link the molecules and, thereby, enhance strength, lessen permeability, increase shrink, and change other properties. May be abbreviated XL.

film, extruded

Film produced by extrusion of molten resin through a die. See film blown and film, cast.

film gauge

The thickness of a film. In metric units measured in micrometres and in the inch-pound system in thousands of an inch (mil) or in gauge units where 100 gauge = 0.001”.

film, heat-shrinkable

A thermoplastic film that is stretched and oriented while it is being cooled so that later, when reheated, it will shrink tightly around the object or package. Heat-shrinkable plastics are used for producing tight wraps around object, label stock, where it is desirable for the label to conform to the contour of a bottle, as tamper-evident banding, and for bundling unit packages.

film, irradiated

A plastic film that has been cross-linked by exposure to gamma radiation.

film, laminated

Two or more films or sheets adhesively bonded together in order to provide a group of enhanced properties not available from the individual films.

film former

A resinous or polymeric material with qualities of forming a tough continuous film. Usually used in reference to films produced from materials dissolved or suspended a solvent.

film master

A record on photographic film representing a graphic element from which a printing plate will be made.

film positive

A positive photographic image on a film base.

film thickness gage

A device for measuring film thickness.

film treatment

The surface oxidation of film to increase adhesion of inks. Film is most commonly treated by corona discharge.

film, multilayer

A film that is built up from a number of layers of similar or different materials. See film, laminated.

film, nonfogging

A packaging film that does not become cloudy from condensation caused by temperature or humidity changes. Also film, antifogging.

film nylon

See film, polyamide.

film, oriented

A film in which the molecular structure has been mechanically straightened and aligned in one or more directions in order to gain strength or to introduce shrinkage characteristics. See orientation.

film, polyamide (PA)

Commonly know as nylon. Transparent, high-strength thermoplastic film, usually used in thin sections laminated to other materials. PA film has outstanding abrasion resistance, good optics, is easily thermoformed, low oxygen transmission rate, and high water vapor transmission rate. It is one of the more costly films.

film, polyester (PET)

See film, poly(ethylene terephthalate).

film, polyethylene (PE)

By far the largest volume transparent flexible packaging material because of a combination of transparency (low density types), toughness, heat-sealability, low water vapor transmission rate, low temperature performance and low cost. Polyethylene films are highly permeable to oxygen and other non-polar gases and have high viscoelastic flow properties. Available with a wide range of specific properties to meet individual market needs.

film, poly(ethylene terephthalate) (PET)

Thermoplastic film of high strength, stiffness, transparency, abrasion resistance, toughness, high temperature resistance, and moderate permeability. Generally used in sections of 0.0005 inch or less and laminated to less expensive materials. PET’s high temperature tolerance makes it a preferred material for ovenable applications. PET is often referred to as polyester. While this term is not incorrect, polyester is a family name for a large group of polymeric materials. PET refers specifically to the polyester used in packaging applications.

film, polypropylene (PP)

Transparent, tough, thermoplastic film usually made by made by cast extrusion. Unoriented film is soft and becomes brittle at low temperatures; however this property as well as strength, stiffness, and clarity can be improved by orientation.

film, polystyrene (PS)

Transparent, stiff film of high permeability and moderate temperature resistance. Made by extrusion or casting. Can be oriented to improve strength.

film, poly(vinyl chloride) (PVC)

Transparent to translucent film (depending on plasticizers and stabilizers), made by extrusion or casting. Excellent grease and solvent resistance, low to moderate gas permeability, moderate temperature range. Can be oriented for shrink packaging.

film, stretch

An extensible film that can be stretched and applied around a product or unit load to hold it in place under tension. Low- density polyethylene, linear low density polyethylene and poly(vinyl chloride) are the most commonly used stretch- wrap materials.

film, tubular

Refers to a film produced by blown film extrusion method, cooling the plastic, flattening the tube by means of nip rolls, and winding it up. Tubular films can be cut into sections and sealed at one end to produce bags with no side seams.

film, unoriented

Film that has not been stretched in any direction for purposes of orienting the molecular structure. See orientation.

film, vented

A plastic film that has small holes that will allow contained produce to breathe. See microperforation.


A study of the printing characteristics of a press using a particular ink and substrate. Fingerprinting is of particular importance when determining the amount of dot gain inherent in the process, for the purpose of improving color reproduction and producing correctly reduced records for bar code reproduction.


May refer to the degree of flatness, surface texture or gloss of a surface.


Any final operation done to packaging before shipping.

finish, matte

A low gloss surface on a material. The opposite of a glossy finish.

finish, mirror

Similar to gloss finish. See finish, gloss.

finish, satin

A type of dull finish, somewhat finer than matte.


(a) Contraction of flexible. The bending qualities of a material. (b) To bend a material. (c) Deflection of rolls or cylinders in a press.

flex cracking

Cracking or fracture of a substrate as a result of repeated flexing, as might be experienced during manufacture or shipping.

flexural strength, flex strength

The ability of a sheet or film to withstand breakage by folding. Flexing strength may be measured by a test to determine the number of folds required to cause failure.


The property of a material that indicates how readily it will bend.

flexibility, low-temperature

The pliability of a material, such as a plastic, at low temperature.

flexible packaging

A package or container made of flexible or easily yielding materials that, when filled or closed, can be readily changed in shape. The construction may be of paper, plastic film, foil or any combination of these. Includes rollstock, bags, pouches, labels/ wraps, lidding, shrink sleeves and stretch film.


See printing, flexographic.


See printing, flexographic.

flexural modulus

The ratio, within the elastic limit, of the applied stress on a test specimen in flexure to the corresponding strain in the outermost fibers of the specimen, measured in pascals (pounds force per square inch.

flexural strength at yield

The measure of resistance of the material to fracture during bending. Measured in either pounds force per square inch or pascals. (Reference method: ASTM D 638.)


Fine strands or filaments made from textile fibers, vegetable fibers (for example, cotton), or animal hair (for example, wool).

One of the two most common pouch seals. A fin seal brings the inside surfaces together and creates the seal, usually by heat sealing. The fin seal is generally not as aesthetically pleasing and uses more material than the lap seal. However the laminate can be simpler since the inside heat seal material is sealed to itself. See lap seal.


A chemical used to stop the developed photographic image from continuing to develop.


A small piece of paper or board inserted in a roll of stock or in a stack of board so it extends beyond the edge to indicate the location of a splice or imperfection. A warning to the next operator of a change from standard condition.


The lifting of a pressure-sensitive label from a surface. See also edge lift.

flame, oxidizing

An oxygen/fuel gas flame having an oxidizing effect caused by an excess of oxygen. Oxidizing flames are used for flame treatment of plastic bottles to improve adhesion of labels and printing inks.


Capable of burning. According to Interstate Commerce Commission regulation, liquids are flammable if their flash point is (27oC (80oF) or lower. Inflammable is a depreciated synonym.

flash dry

Drying or curing by the short duration application of high heat.

flash point

The lowest temperature at which a substance can be ignited under standard test conditions.


(a) When describing a printed surface, the lack of contrast and definition of tone. (b) Opposite of glossy; dull, matte.

flat pack

A continuous web folded at perforations to form a flat pack rather than a roll. See fanfold.


(a) Rheological properties of a fluid. (b) The property of an ink causing it to level out as would a true liquid. Inks of poor flow are classed as short in body, while inks of good flow are said to be long.


A horizontal-flow wrapping machine typically used to wrap irregularly shaped items such as baked goods, apparel, and candy bars. In the most usual configuration, the wrapping material is unwound from the supply roll and passed over a forming box that shapes it into a rectangular tube at the same time as product flows through the box and into the formed tube. The overlapping edges along the bottom of the tube and the two ends are heat-sealed, and the completed package cut free from the wrapper web.

flow out

The ability of an ink, adhesive, or coating material to spread out and evenly wet out a substrate surface.


A graphic representation of a work process in which each step is detailed in its optimized or desired sequence and time frame.


The ability of a material to flow. The ease of flow of a material. As opposed to viscosity, the greater the viscosity, the less the fluidity. Also flowability.


That property of a coloring agent that shifts ultra violet wavelengths into the visible light spectrum. Fluorescent agents are used to create various unusually bright day-glo type colors.


Treating polyethylene surfaces with fluorine gas to improve chemical resistance and barrier properties. The fluorine reacts with the material surface to produce, in effect, a fluoropolymer layer.


Hydrocarbons that have one or more hydrogens replaced with fluorine. Many of these also incorporate chlorine and would be referred to as chlorofluorocarbons (CFCs). Lower molecular weight members are gaseous and have been used as aerosol propellants, cleaning solvents, and refrigerants. The use of many of these is restricted because of a connection to ozone layer destruction. High molecular weight fluorinated and chlorofluorinated hydrocarbon polymers are noted for their chemical inertness and temperature resistance

amongst other unique properties. Products such as tetrafluoroethylene (Teflon) and chlorotrifluoroethylene (Aclar) fall into this polymer group.

flush-cut top

A multiwall shipping sack in which all walls are cut evenly across the top (not stepped).

flushing, gas

The replacement of air in a package with an inert gas such as nitrogen to minimize oxidative deterioration.


The wave-shaped or corrugated formation of the center member of a corrugated fiberboard.


Describes ink or other coating material that is thrown off the inking rollers of a printing press.

flying splice

The splicing of the tail end of one web roll to the lead end of the next web roll without stopping the machine.

foaming agent

Chemicals added to plastic resins that when heated generate gas that expands the plastic to produce a foamed or expanded plastic material.

foam, closed-cell

A cellular plastic in which a majority of the cells have no connection to adjoining cells.

foam, plastic

Plastic materials into which gas has been introduced to give a lightweight structure. Gas cells may be interconnected to give an open-cell foam, or unicellular to give a closed-cell foam. Foams are most generally used as cushioning materials, trays, chests, boxes, platforms, and for insulation properties. Polystyrene, polyethylene, and polyurethane are the most commonly expanded plastics.

foam, polystyrene

A form of expanded polystyrene with open or closed cells depending upon its method of manufacture. Open cells are made by the extrusion process, closed cells are made by steam chest or radio frequency expansion processes. Extruded polystyrene foams are produced by melting polystyrene with a blowing agent in plasticating equipment under heat and pressure and passing through a die into the atmosphere. Nucleators may be used to control cell size. See blowing agent, nucleating agent.


A fountain ink condition where the ink fills with unwanted bubbles. Normally resolved by addition of defoaming agents.


An unsupported thin metal membrane, typically aluminum, less than 152 micrometres (0.006 inch) thick. Above 152 micrometres thickness, the metal is called sheet. In many European countries the French word feuille (also pronounced “foil”) is used to describe any thin material (for example, plastic films) as well as thin metals.

foil, dry

Aluminum foils as processed may have residues of processing oils on the surface that may interfere with printing or adhesive bonding. A dry foil is one in which these surface residues have been removed.

foil, hard

Aluminum foil in a cold-worked or strain-hardened condition.

for position only (FPO)

A low-quality image used only to indicate the placement in the final version.


That which can impose a change of velocity on a material body. Mathematically force is the product of mass and acceleration.

form-fill-seal machine (FFS)

A packaging machine or system that forms, fills, closes, and seals a package in one continuous- or intermittent- motion operation. A filling machine that is fed with a flexible packaging stock from a roll. The stock is folded to the desired package shape and stabilized by heat sealing. The product is placed into the formed package, and the remaining opening is sealed. Machines can be configured so that the stock travels horizontally through the machine (horizontal form-fill-seal) or vertically through the machine (vertical form-fill seal).

form-fill-seal, horizontal (HFFS)

A form-fill-seal
machine in which the
roll-fed flexible
packaging material is
unwound and shaped
while traveling
horizontally through
the machine’s
operating stations. A
horizontal FFS
machine occupies
greater floor space than a vertical FFS machine, but has the advantage of having the option of installing more operating stations (for example, multiple filling stations) along the travel path.

Aluminum foil bonded to other materials such as paper, board, and films. The construction is referred to as supported foil If the added laminate material adds significantly to the foil’s stiffness or tear strength.

foil, soft

Aluminum foil in the annealed condition.


The complete set of letters, numbers, and punctuation marks of a particular design and size of type.

Food and Drug Administration (FDA)

The U.S. agency within the Department of Health, Education and Welfare that is concerned with the safety of products marketed for consumer use, particularly those substances that might be ingested, applied to the skin, or used in therapy or prostheses.

food, high-acid

Foods that have a natural pH of 4.6 or lower.

food, low-acid

A food with a finished equilibrium pH greater than 4.6 and a water activity greater than 0.85. Alcoholic beverages are excluded from this definition.

foodservice packaging

Packaging designed to deliver food products to restaurants, schools, hospitals, factory cafeterias, and other institutions. Foodservice packaging normally contains larger quantities than intended for normal retail and the demand for aggressive point-of-purchase display is reduced.

form-fill-seal, vertical (VFFS)

A form-fill-seal machine
in which the roll-fed
flexible packaging
material is unwound and
shaped while traveling
upwards vertically over
a forming collar and
down through the
sealing and filling area.
A horizontal VFFS
machine occupies less
floor space than a HFFS
machine, but has the
disadvantage of having
only one filling location along the travel path.

form roll

A roll in a lithographic printing press used to distribute ink to the printing plate. The roll that picks up the ink or coating material from the fountain and applies it to the transfer roll. In some design configurations, the transfer roll also acts as the fountain roll, particularly when a doctor blade ink-metering system is used.


That part of a paper, or film-bag machine around which the web of material is folded and seam-pasted or heat-sealed into a tube.

fountain solution

In lithography, a water-based chemical solution used to dampen the plate and keep nonprinting areas from accepting ink. A dampening solution.

four-color process

Printing with yellow, magenta, cyan, and black ink using halftone screens to create all other colors.

fourdrinier machine

A type of paper and paperboard making machine on which the web is formed by depositing pulp furnish on a moving, endless wire screen. The screen shakes as it travels, causing the pulp fibers to crisscross and mat. Initially water is then removed by gravity followed by suction boxes until the wet paper web can be separated and passed unsupported, to the pressing and drying sections of the machine. Caliper of the paper or board is determined by the consistency and rate of feed of the furnish, and length and travel speed of the screen. Named for the inventors, Henry and Sealy Fourdrinier.


Acronym for the Flexible Packaging Association, Linthicum Maryland. FPA is the leading trade association for manufactures and suppliers of flexible packaging,


Abbreviation for feet per minute, a measure of surface speed.


See for position only.


An adjective used to describe some quantity that is less than unity, or a common commercial convention or standard. For example, a fractional melt flow rate would describe a polymeric material with a melt flow rate of less than 1. A fractional coffee package would describe a pouch or sachet of coffee containing less than 1 pound.

freezer burn

the drying out of a frozen food product when water is lost by sublimation.


The resistance existing between two contacting bodies which tends to prevent motion relative to each other.

friction, coefficient of

See coefficient of friction.

frost line

In blown extrusion of plastic films, that zone at which the film reaches its final diameter. This point is also approximately the point at which the plastic has cooled from a thermoelastic to a thermoplastic solid.


Acronym for the Flexographic Technical Association, Inc., Ronkonkoma, New York.


Refers to a dye or pigment likely to deteriorate, change or fade.

functional coating

A coating that performs a specific purpose such as acting as a barrier or altering surface coefficient of friction.


A chemical compound used to destroy or prevent the growth of mold, mildew, or similar fungi.


(a)To join two surfaces by heating them to their softening or melting point. The melting together of thermoplastic resins. (b) fusible: Capable of being melted or liquefied by action of heat.


The melting together of two separate materials to form a single mass.


Projecting surface fiber on a sheet of paper.


Acronym for the Gravure Association of America, Rochester, New York.


Alternate spelling of gauge.


See dot gain.

gamma correction

The correction of tonal ranges in an image, most commonly by the adjustment of tonal or gamma curves.


The particular range of colors available from a specific input device, output device, or pigment set.


Space between cylinders through which material has to pass.


Openings between layers within a wound roll of adhesive tape.

gas flushed

A package that has been flushed with a gas other than normal air. For example, a package may be nitrogen-flushed to expel oxygen that might take part in biological activity that would decrease a food’s shelf life. Gas-flushed packaging also is described as controlled- or modified-atmosphere packaging.


(a) The action of a packaged product when producing gas, e.g., the release of carbon dioxide from freshly roasted coffee beans. (b) Removing air from a filled package and replacing it with another gas, such as carbon dioxide or nitrogen. See gas packaging; gas packing.


Acronym for Graphic Arts Technical Foundation, Sewickley, Pennsylvania.

gauge, gage

(a) (noun) An instrument for exact measuring. (b) A unit of thickness measure for thin materials such as sheet, film and wire. The exact dimension described by gauge can vary depending on the material being measured. (c) (verb) To measure exactly.

gauge band

A thickness irregularity found in rolls of film. A thicker area or thinner area at some locality over the width of a flat film will produce respectively, a raised ring or a depressed ring in a finished roll. Such films can cause winding problems and when unwound, tend not to lie perfectly flat.

gauge, film

A unit of thickness measure expressed by a number that has a dimensional equivalent that varies for different materials and for different standards. When measuring the thickness of a film, 100 gauge = 0.001 inch. Thus, a 75-gauge film would be 0.00075 inch thick. In ISO units, film gauge is expressed in micrometres.

gauge, UPC printability

A series of dark bars arranged in a specific pattern used to determine print gain of a Universal Product Code (UPC).


See chromatography, gas.


See gray component replacement.

gear marks

A defect in flexographic printing. Usually appears as uniformly spaced, lateral variations in tone exactly corresponding to the distance between gear teeth. Also called gear streaks.

gear streaks

In printing, parallel streaks appearing across the printed sheet at the same interval as gear teeth on the cylinder.

Geiger press

A small bench-scale gravure printing press used for evaluating and proofing gravure inks.


A jelly-like material formed by coagulation of a colloidal liquid.

gas packaging

A packaging method involving the replacement of air within a container by a gas that contains practically no oxygen. Gases such as carbon dioxide or nitrogen can prevent chemical change of the product contained due to oxygen in the headspace air or in the product. In addition carbon dioxide in higher concentrations reduces or stops biological activity. Gas packaging is also used to provide equilibrium pressure in the package so that product, such as spices, are not compressed as well as inflating flexible packaging into a protective pillow-like form. See also modified atmosphere packaging.

gas sterilization

In medical packaging, the process of sterilizing flexible packaging using ethylene oxide gas.

gas transmission rate (GTR)

The quantity of a given gas passing through a unit area of the parallel surfaces of a film, sheet, or laminate of a given thickness over a given time under the test conditions. Test conditions may vary and must always be stated. The SI unit of GTR is mol(m2.s) but other systems, some of them using mixed metric and inch/pound units, are still in common use. ASTM tests for gas-transmission rate through plastic film and sheeting are D 1434 and D 3985.


general gas law

Combining Boyle’s law and Charles’ law used to compute the change in volume, pressure, and temperature of a gas. Essentially, it states that the product of pressure and volume, divided by the temperature, remains constant.

generally recognized as safe (GRAS)

A Food and Drug Administration designation, GRAS is used to describe materials that will come in contact with foods or pharmaceuticals, and that through historical experience have not been shown to have any objectionable effects.

generation (artwork)

Each succeeding stage in reproduction from the original copy.


Pertaining to or applicable to all members of a genus or class.

generic design

Not protected by trademark registration.


In printing, the appearance of unwanted images usually only faintly discernible in areas of solid printed ink coverage. In lithography, the ghost image appears as a lighter area on a subsequent print due to local blanket depressions from previous image areas. In flexography, ghosting is sometimes used to describe the slight halo effect bordering solid color areas.


A prefix used to denote 1 billion.


The amount of product in a package that exceeds the stated fill weight or number.

glass transition temperature (Tg )

A reversible change that occurs in an amorphous polymer or in amorphous regions of a partly crystalline polymer when it is heated from a lower temperature into the glass transition; a range peculiar to each polymer. During the transition, the molecular chains, normally coiled, tangled, and motionless at the lower temperatures, become free to rotate and slip past each other. Tg is characterized by a sudden change from a hard or brittle condition to a flexible, leathery, or elastomeric condition. Physical properties such as coefficient of thermal expansion, specific heat, and density usually undergo changes at the same time. See temperature, glass transition.


A smooth, dense, glossy, translucent paper made from highly beaten chemical pulps. The dense packing of finely divided fibers results in very low porosity. Often used where resistance to grease is required, hence it is often called greaseproof paper.


The amount of surface sheen or reflectance of a substrate. The degree to which a surface approaches perfect optical smoothness in its capacity to reflect light. Gloss is measured with a gloss meter described in ASTM D 523.

gloss meter

An instrument used to measure the gloss intensity of a surface.


(a) (noun) Although the term is frequently used to describe any sticky substance that can be used to join two surfaces, it more correctly refers to a protein-based substance derived from animal cartilage, bones, and skins. True animal glues are rarely used in packaging. The preferred term for synthetic bonding agents is adhesive. (b) (verb) To join two substrates with an adhesive or a glue.

glue assists

Incisions or serrations cut partly through a clay-coated board in the areas where an adhesive will be applied. The incisions provide a path for adhesive to get past the clay coating and into the substrate paper itself in order to produce a stronger bond. See clay lift.

glue buildup

Excess glue that accumulates on machine rollers, pads, etc., during operation of the machine.

glue line

The line of adhesive between the two surfaces to be adhered. Also called the paste line.

glue-line, starved

A lack of sufficient adhesive between two adherends resulting in a weak or failed bond. Also joint, starved.

glue, white

A nonspecific term used to describe a water-based emulsion adhesive. Most commonly, white glue is a poly(vinyl acetate) emulsion.


See good manufacturing practice.


An instrument for measuring the contact angle of a drop of water applied to a surface as a means of determining surface treatment levels.


An adhesive’s ability to quickly form an initial bond with a surface using a minimum of pressure. Similar to tack.


The arrangement or direction of fibers in a fibrous material such as paper or the direction or molecular orientation in a nonfibrous material.

grain direction

The direction parallel to the grain in paper. When pulp is run through a paper machine, the fibers tend to orient in a direction parallel to the motion of the machine. This grain direction or machine direction (MD) of paper and paperboard is an important strength factor in container design. There is greater tearing strength across the grain than with it. There is greater tensile strength in the grain direction. Grain is more pronounced in paper or board made on a cylinder machine than on a Fourdrinier machine.


A printing defect where the ink film has an irregular pebbly appearance rather being smooth.

gram (g)

Metric unit of mass. One kilogram is equivalent to 1000 grams, and 453.6 grams equals 1 pound.


The mass in grams of one square metre of material. Grammage can be used to describe sheet material or the rate of application of a liquid adhesive or coating. Basis weight and ream weight are related terms in the inch/pound system.


The design and decoration of the exterior surfaces of a package and the use of the photographic and printing technologies that are employed in labeling and decorating packages.


Describes a process that depends on weighing. For example, a gravimetric filler would be one where product is weighed into the package. Gravimetric analysis is one where the mass (weight) rather than volume or other characteristic of participating components is considered.

gravity, specific

The ratio of the weight of a material to the weight of an equal volume of water at the same temperature. Specific gravity is a depreciated term. Density is a more commonly used value to indicate the mass per unit volume of a material.

gravure printing

The process of printing with a thin, quick-drying ink from a cylindrical surface having an etched (recessed) design. The opposite of letterpress and flexographic printing, in that the design areas are recessed into the plate instead of being in relief. See printing, gravure.


A type of microscope designed for inspecting and measuring the engraved cells of anilox rolls or gravure cylinders. Measures both vertically for depth and horizontally for width. Also used when referring to surface finish of a cylinder.

gray balance

The dot values or densities of cyan, magenta, and yellow that produce a neutral gray. A neutral gray has no color cast.

gray component replacement (GCR)

A process where the least dominant process color is replaced with an appropriate amount of black in areas where yellow, magenta, and cyan overlap. GCR reduces color variation on the press. Also called achromatic color removal.

gray levels

Discrete tonal steps in a continuous-tone image, inherent to digital data. Most continuous-tone and computer generated images will contain 256 gray levels per color. Current printing processes are not capable of accurately reproducing this range.

gray scale

A strip of standard gray tones, ranging from white to black, placed at the side of original copy during photography to measure tonal range and contrast (gamma) obtained.


A material that is resistance to the take-up and penetration of grease.

green strength

The strength of an adhesive bond before it is completely cured or dried. Usually used in connection with emulsion- type adhesives, where the early breaking of the emulsion results in rapid development of a strong bond, which improves further at a much slower rate as the water evaporates. Pressure-sensitive adhesive bond strength also increases with time.


Refers to a paper that is made primarily from low cost mechanically extracted fiber rather than fiber extracted by chemical means.


See gas transmission rate.

guide corner

That corner of a sheet material such as paper where the gripper and side guide edges meet. Register is obtained by accurately locating the gripper and side guide edges.


A cutting machine where the cut is made by a long knife that descends vertically on the material to be cut. Used mostly for paper products.


(a) A water-soluble amorphous substance exuded by or prepared from plants, which is sticky when moist but hardens when dried. (b) Any natural or synthetic material having the above properties.

gun, hot-melt

A handheld or fully automatic device used for applying hot- melt adhesives.


The bellows fold, pleat, or tuck along the side of a bag, sack, pouch, or sheet product. The gusset allows a bag to take up a rectangular cross section when opened. The capacity of a gusseted bag is measured with the gusset unfolded.


See hazard assessment critical control points.


A halftone image is a simulation of continuous tones composed of a large number of ink dots of varying sizes. Areas where the dots are larger will appear to be more strongly colored, while areas with smaller dots (highlights) will be less strongly colored. If the ink being used is black, a range of gray values going from black to white can be created.


A value related to the light transmittance of a material such as plastic film. Haze describes a cloudy or turbid appearance of an otherwise clear film caused by the scattering of light from within the specimen or from its surface. (Reference method ASTM D 883).

haze, percent

To measure the percent of haze, a light beam is projected through the material being measured and into a sphere and light-collecting box. Any scatter, which deviates from the straight beam of light passing through the sphere, is measured as percent haze. As the percent haze values increase, clarity is reduced. (Reference ASTM 1003.)


Refers to the health and beauty aids market segment.


See polyethylene, high-density.

header card

A folded card, usually printed, which fits over the mouth of a bag or pouch, and is attached by staples, adhesives, or heat sealing. Most commonly the bag is clear plastic to display the product and the header card has a hole to allow for Peg-Board display.

Heaford press

A small proof press used with flexographic printing plates in order to check print register, color, traps and bleeds.

heat-deflection point

For plastics, the temperature at which a standard test bar deflects 0.010 inch under a stated load of either 66 or 264 psi. (Reference test method: ASTM D 648.)

heat history

See history, thermal.

heat, radiant electric

A method of heating and conditioning materials. The type of radiant heat source and temperature are chosen to correspond with the materials used.

heat resistance

Conventionally taken to be the maximum temperature that a material will withstand and still retain at least 50% of its physical properties when subjected to this temperature for a specified time.

heat sealer

A machine or device used for producing package seals by the action of heat and pressure.

heat seal, induction

See sealing, induction.

Peripheral lines around printed detail caused by excessive ink, excessive impression pressure, dried ink on plate shoulders, or faulty plate shoulders. Most frequently found in flexographic, letterpress, and similar relief plate printing methods. An undesirable peripheral outline of the printed image.

hand proofer

A hand-held device for applying a measured amount of ink for the purpose of doing ink draw- downs when checking ink colors as applied to a substrate.

hang tab

The package extension, punched with a suitable hole, used to hang the package for display on Peg-Board retailing systems.

hard roll

A roll of material that has been wound under excessive tension or pressure.


A paper containing a large amount of sizing material thus providing it with a high degree of moisture resistance. Boards for frozen food products and liquid or wet products would be hard-sized. Opposite of slack-sized. See size.


A substance or mixture of substances added to an adhesive or coating material to initiate or promote a curing reaction. Hardeners frequently act as a catalyst to promote cross- linking or polymerization.

hazard assessment critical control points (HACCP)

An internationally recognized systematic and preventive approach to product safety that addresses biological, chemical and physical hazards through anticipatory and preventive action rather than by finished product inspection. controls will be applied in a systematic and consistent manner.

heat sealing

A method of joining two surfaces by heat fusing them or their coatings together. The quality of the seal is determined by the seal substances, time, temperature, and pressure.

heat-seal strength

The strength of a bond formed by heat sealing measured in either tensile or peel modes.

heat sensitivity

The tendency of a material to undergo changes in properties or color, or to degrade at elevated temperatures. Severity of change is always a matter of both temperature and time.

heating, dielectric

The process of heating poor, but polar electrical conductors (dielectrics) by high-frequency fields. At frequencies above 10 MHz, sufficient heat to melt and heat seal many plastics can be generated at low, safe voltages. The material to be heated is placed between two electrodes connected to a high- frequency current supply. The electrodes act as capacitor plates and the material becomes the dielectric separating them. As the field changes polarity, the polar groups in the dielectric oscillate in an effort to keep their poles toward the electrode that is momentarily the opposite charge. The molecular friction is dissipated as heat. Dielectric heating is most effective for materials such as poly(vinyl chloride) that have high loss factors because of their polarity. Nonpolar plastics with low loss factors, such as polystyrene and polyethylene, cannot be practically heated by dielectrics.

heating, infrared

A heating process used in thermoforming and for drying coatings and inks, employing lamps or heating elements that emit invisible radiation just longer in wavelength than visible light.

heavy body

Having a high viscosity.


A printing screen where the dots are diamond shaped rather than round.

HEPA filter

High Efficiency Particulate Air filter refers to filtering systems capable of removing microscopic particles including a significant number of microorganisms from the airflow.


Airtight or impervious to gases or fluids under normal conditions of handling and storage.

hermetically sealed

A container that is designed and intended to be secure against the entry of microorganisms and to maintain the commercial sterility of its contents after processing.

herringbone roll

A roll engraved with grooves or ribs spiraling out from the center to each end. A material passing over a herringbone roll is constantly been spread out toward the roll ends.


A six-color primary process ink system, pioneered by Pantone. The Hexachrome system adds a vivid orange and an intense green to enhanced versions of the four standard process colors. This expanded color range is said to produces clean well-balanced colors, and is capable of more closely emulating over 90% of Pantone Colors. The addition of orange as a primary color allows for better flesh tones while using less ink than can be had with the traditional magenta and yellow blends. The process has been adopted by some publication printers but has had limited application in package printing.


See form-fill-seal, horizontal.


Refers to the household and industrial chemicals market. This includes such products as industrial chemicals, cleansers, fertilizers, waxes, herbicides, pesticides, polishes, motor oils and swimming pool chemicals. Usually used in reference to the plastic bottle market.


A print defect most commonly related to lithographic printing. An uninked irregular or doughnut-shaped spot arising in printed matter. Irregular spots often are caused by dust or pick-outs that adhere to the offset blanket or plate and interfere with the transfer of ink. Doughnut-shaped spots are caused by foreign particles depressing the offset blanket and preventing contact between plate and blanket.

hiding power

The degree of opaqueness in an ink or coating that prevents show-through of the substrate.

A heating process similar to dielectric heating, but using frequencies in the 109- to 1010- Hz (radar) range. Heating occurs because of resonance movement of water molecules. Products that do not contain water, do not respond to microwave energy. Many packaging applications need to be compatible with microwave energy since this is a common method of heating prepared foods. Very light metallizing helps to convert microwave energy to heat energy and is used in some applications to create local hot spots. See susceptor packaging. See also heating, dielectric.

heating, RF

See heating, dielectric.

heat set

A coating or adhesive that hardens with the application of heat. See cure.

heat-shrink property

The property that allows a plastic material to shrink when heated to about glass transition temperature.

high barrier

Said of a material or package that has very low gas permeability characteristics, that is, it offers a great deal of resistance to the passage of a gas through its volume. The term should be further qualified by stating the gas or general class of materials to which barrier is provided since barrier properties are closely related to the nature of the permeating gas.


The lightest or whitest parts in a picture. The bright tone areas of a print in which 25% or less of the surface is covered with ink. In halftone reproduction, it is represented by the smallest dots or absence of dots.


A bar chart compiled to show the frequency of occurrence of a particular characteristic or condition. The measurements or observations are first sorted into a number of classes, usually of uniform width, and a count is made of the number in each class. The counts may be converted to percentages of the total number measured. The finished chart shows the range of values on one axis and the number or percentage of observations on the other.

history, thermal

The integrated product of time and temperature for a plastic, from the time it was first subjected to a high temperature to the moment under consideration. Thermal history can affect many polymer properties (for example, crystallinity) and molding or shaping stresses can produce further final product differences. All formed plastics have a thermal history.

hold down roll

A roll whose function is to keep a web in contact with another roll or surface.

nation on the inner surfaces of the container (usually a bottle) is destroyed by the hot liquid without heating the bottle itself, as in the technique of in-bottle pasteurization. Hot filling also is used to reduce the viscosity of viscous liquids and, therefore, increase filling speeds. Hot fill packaging is typically constructed of materials other than polyethylene on account of polyethylene’s low softening point.

hot melt adhesive

See adhesive, hot melt.

hot melt coating

The application of a molten polymeric material to a base stock.

hot stamping

See printing, hot-stamp.

hot tack

The ability of adhesive material to adhere while still at melt temperatures.

hot-tack strength

(a) The tack of a hot-melt adhesive while still in the melt form. (b) In heat sealing, the strength of the seal at the end of the dwell and just when the sealing dies open.

hotel-restaurant-institutional (HRI)

Describes a market segment requiring packages containing larger quantities and possibly special features as compared to the same product offered in retail establishments.

household roll

A roll of flexible packaging material of small outside diameter for household use. Utility roll.


See hotel-restaurant-institutional.


That characteristic that places a color in its correct position in the spectrum and allows differentiation between colors such as red, green, blue, and so on. Refers to a particular color of the visible spectrum.


To introduce water vapor into the atmosphere in order to increase humidity levels.


Refers to water vapor in air. See humidity, relative and humidity, absolute.

humidity cabinet, chamber

A box or enclosure constructed so as to allow control of the enclosed humidity level. In practice this also requires good temperature control as well. Typically used in performance testing of materials and packages as well as for shelf-life studies.

holding power

The ability to hold stress as in an adhesive bond. Holding power requires both good adhesive and cohesive strength.


In printing, a property of coated paper with low ink absorption that allows ink to set on the surface with high gloss. Papers with too much holdout cause problems with offset lithography.


A method of producing a three-dimensional image in a film or foil by using interference patterns from a split laser beam.


Of the same composition or construction throughout.


A polymer that is produced by the polymerization of a single monomer species. For example, ethylene polymerizes to produce polyethylene.

hot filling

A process where the product, usually a liquid, is passed through a heat exchanger, and then filled at temperatures somewhat below 1000C (2120F).

humidity, absolute

Absolute humidity is the actual weight of water vapor contained in a unit weight of air. See humidity, relative and humidity, ambient.

humidity, ambient

The uncontrolled humidity present at any given time. See humidity, absolute and humidity, relative.

hybrid press

A printing press that has more than one type of printing method in the line. For example, a gravure or offset press with flexographic stations. Also combination press.


See wetting.


Any chemical compound containing only hydrogen and carbon atoms. As a class, hydrocarbons are non-polar, insoluble in water and combustible. Lower molecular weight hydrocarbons are used as solvents. Paraffin waxes are somewhat higher in molecular weight. Polyethylene and polypropylene are polymeric hydrocarbons.

hydrocarbon, aliphatic

Solvents derived from crude oils in which the hydrocarbon chains are predominantly linear rather than cyclic as, for example, would be found in aromatic hydrocarbons such as benzine, toluene, or kerosene. Aliphatic hydrocarbons tend to swell natural and butyl rubber. See also hydrocarbon, aromatic.

hydrocarbon, aromatic

Solvents such as benzene, toluene, and zylene, whose structure is characterized by ring or cyclic formations, as compared to aliphatic hydrocarbons that have linear chain structures. Many aromatic hydrocarbons can present health hazards and their use is avoided where possible. See also hydrocarbon, aliphatic.

hydrogen peroxide

A bacteriostat commonly used to sterilize package components. Hydrogen peroxide has the advantage of decomposing to water and oxygen. Typically used to sterilize packaging in aseptic packaging systems such as the Tetra Pak and Combibloc systems.


The reaction of a compound with water resulting in destruction of the original compound and the formation of at least two new ones.


An instrument used to measure the density of a fluid.


Said of a material that has a strong affinity or attraction for water; opposite of hydrophobic.


Having a strong repellency or aversion to water. The opposite of hydrophilic.

hydrostatic pressure

The pressure exerted equally in all directions at points within a confined fluid (liquid or gas.)


Any material that increases in dimension when it absorbs moisture. Paper products are hygroexpansive.


An instrument for measuring the relative humidity (moisture content) of air.


  • Having a strong tendency to absorb water from the air. Many food and pharmaceutical products are hygroscopic and require water vapor barriers to preserve their quality. Polymer resins such as poly(ethylene terephthalate and polyamide are hygroscopic, and may require drying before being extruded or molded. Paper is also a hygroscopic material. (b) hygroscopicity: The material’s ability to absorb water vapor from the surrounding atmosphere. A hygroscopic material will reach an equilibrium point for a specific relative humidity, at which point, water will be neither gained nor lost.



In graphic arts, a recognizable symbol, image, or word mark.

idler roll

Roller mechanisms on converting machines used to support, smooth, or direct the substrate in its course of travel through a machine. Idler rolls are not driven.


A two-dimensional representation of an object or a scene formed by creating a pattern from the light received from the scene.

image area

(a) The area of the printing plate that transfers ink to the substrate. (b) The printed area of a receiving surface.

image carrier

The plate, cylinder, screen, or digital record that carries information suitable for reproducing an image on a substrate.

image processing

Encompasses all the operations that can be applied to digital image data. These include, color adjustment, image assembly, image enhancement and preprocessing, and other image pattern recognition techniques.


A device used to produce negatives directly from the computer’s digital record.

impact modifier

An additive, usually an elastomer incorporated in a plastic to improve its impact resistance.

impact resistance

The relative resistance of a material or product to fracture when impacted. There are many test procedures evaluating some aspect of impact resistance. Some of these are material tests, for example, evaluating a plastic material’s resistance to impact. Such material tests are good for comparing the properties of two candidate materials. However, a good material can still be made into a poor product. Other tests (performance tests) focus on the actual manufactured product, for example, drop testing filled plastic bottles on a hard floor.

impact strength

A measurement of the energy needed to fracture a material. A pendulum impact tester or a dart impact tester are typically used to determine this value. (Reference ASTM D 1709.)

impact tester

Any device for striking a controlled impact on a surface.

Generally the device consists of a predetermined weight, which can be dropped from a measured height to strike with a rounded tip of predetermined size.


A condition of being less than optimal; a departure of a quality characteristic from its intended condition.


Partial or complete saturation of a material with another substance, such as the impregnation of paperboard with paraffin, resins, or other protective materials.


(a) A mark such as an indentation made by a die, printing press, or other marking device. (b) The pressure required to transfer ink from printing plates to the substrate being printed. (c) The image transferred from the printing plate to the substrate. (d) One copy or one color of a design made by passing a sheet once through a printing press. (e) The number of blanks printed or cut by a cutting die.

impression, kiss

The lightest possible impression that will transfer the film of ink from transfer roll to the plate and from the plate to the substrate.


A machine, for example, a printing press, where the operating stations are placed in a horizontal line. See also straight-line configuration.

Induction seal

See sealing, induction.

industrial packaging

Packaging of goods for industrial buyers rather than for individual consumers.


A device or mechanism designed to move material or product into a machine. In its broadest sense, the entering point or beginning of a mechanical production sequence, as in infeed end.

Infrared (IR)

A region of the electromagnetic spectrum adjacent to and slightly longer than the visible portion. IR wavelengths are between 0.75 and 1000 micrometres. IR is used as a source of heat energy. Also referred to as infrared radiation.

infrared scannable

Codes and markings capable of being read by an infrared scanner.


Any substance that slows or prevents chemical reactions or biological activity such as those described as corrosion, oxidation, mold, growth, and so on.


Basically, printing inks consist of coloring materials dispersed in a carrier or vehicle. The more common inks may be broadly classified into the following main categories, depending on the methods by which they dry: (1) Absorption of the vehicle by the stock on which the ink is printed. Newspaper inks generally fall into this classification. (2) Oxidation and/or polymerization. In these inks the vehicle is changed by oxidation and/or polymerization from a fluid to a plastic or solid film. Lithographic and letterpress inks are generally of this nature. Polymerization of certain inks can be initiated by brief exposure to ultraviolet light or electron beam. (3) Solvent loss. Solvent removal leaves the pigments embedded in a resin. For high-speed printing, the solvent is driven off by heat. Letterpress, gravure, and flexographic inks use this principle. Inks can also be classified by references to aspects or components of the formula.


(a) Having the property of being able to accept or be wet-out by an applied ink. (b) May be used in reference to a substrate to be printed or to the printing plate itself. For example, lithographic printing plates have ink-receptive and ink- repellent areas.

ink absorptivity

The characteristic that determines the rate and amount of ink vehicle penetration into the paper substrate after deposition from the press plate or blanket.

ink bleed

The penetration of an ink into a substrate causing discoloration of the substrate or the running of one color into another.

ink drawdown

See drawdown.

ink driers

Substances added to inks that promote the drying or solidification of the ink. Typically driers increase the rate of oxidation or polymerization of resins used in inks.

ink fountain

The reservoir, chamber or other system on a printing press that holds the ink for distribution to the inking system.

ink holdout

The extent to which a printed surface resists penetration by the vehicle and/or pigment of a given ink formulation. Depending on the desired application, it may be expressed as optical density, percent blackness, or gloss.

ink, electron-beam curing

Ink that can be cured by exposure to electron-beam (EB) radiation. The ink is formulated using highly reactive cross- linking vehicles, which cure under EB radiation.

ink, flexographic

Fast-drying low viscosity inks used in flexographic printing. Consists of a pigment or sometimes a dye dispersed in a vehicle made from a resin and a volatile solvent. Formerly called aniline ink.

ink, gravure

A low viscosity, usually solvent based ink, used to print with the rotogravure process. See rotogravure.

ink, high-gloss

Ink which, when dried, has a high gloss without the use of overprint varnishes. These inks require the use of vehicles formulated to resist penetration of the stock. They also must have a relatively low pigmentation so that after drying, the pigment particles are still covered by a smooth film of binder.

ink, lithographic

Ink designed to be used in offset lithography. The ink is highly pigmented and hence is a very heavy tacky paste. High pigment loadings are required because offset printing processes, split the ink twice resulting in low ink thickness laid down on the paper. Also paste ink. See printing, lithography.

ink, metallic

Ink with a metallic luster produced by suspending bronze, aluminum or other metallic powders in an appropriate vehicle. Attains characteristic sheen by the property of “leafing,” in which the individual flat particles lie parallel to the surface of the ink. In addition to the gold, copper, and silver of the natural metals, lustrous tints of other colors may be produced by adding a small amount of transparent color to aluminum inks.

ink mileage

Printing ink consumption typically stated as per unit area of substrate during printing.

ink, offset

Most commonly used in reference to ink used in offset lithography. See ink lithographic.


An instrument for measuring the tack of printing inks.

ink, opaque

An ink that completely hides the underlying substrate as opposed to a transparent ink. Opaque inks might be used on clear plastic materials or on substrates having dark or an otherwise unfavorably colored surface. Most process printing inks are transparent and rely on using the white of the substrate as one of the colors.


A thin layer or membrane of material that remains attached across the opening of a jar, bottle, or other similar container after the threaded closure is removed. Innerseals are attached by induction sealing, pressure-sensitive adhesive, or glued- glassine. All innerseals provide some measure of barrier and leakage protection. Correctly engineered innerseals may offer tamper evidence.


In chemistry, that group of compounds that are not primarily based on carbon and hydrogen.


The process of measuring, examining, testing, gauging or otherwise comparing an item with the applicable requirements and/or contract specifications.

Institute of Food Technologists

The professional society of food scientists and technologists in the United States. Based in Chicago, Illinois.

institutional packaging

Larger sized packages intended to deliver product to organizations such as restaurants, hotels, the military, factories, or schools.


A tensile testing machine made by Instron Corp., Canton, Massachusetts. Instron machines have been so omnipresent in plastics testing that “Instron” has taken on a near-generic character.

integral hinge

A plastic part design that has a hinging portion as part of the molding. For example, a one-piece injection-molded box where a portion of the plastic is able to repeatedly flex and act as a hinge. Many flip-top closures are one-piece live-hinge designs. Polypropylene has the best integral hinge properties. Also called a live hinge.

intensity (of a color)

Purity of hue or color tone or the degree of hue as seen by the eye.

ink tack

(a) A measure of the body or cohesiveness of ink. The force required to split an ink film. (b) The separation force of ink needed for proper transfer and trapping on multicolor presses. An overly tacky ink has high separation forces and can cause surface picking or splitting of weak paper.

ink, thermoplastic

An ink that can be softened by heating. Such an ink can be applied to a carrier web such as a release paper, and then transferred from the release paper by a heated die to the substrate to be decorated, as in heat-transfer printing.

ink, thermosetting

An ink that during the drying or setting process undergoes a chemical change (cross-linking) that produces a thermoset polymer. The chemical changes may be initiated by heat, oxidation, radiation, catalysts or the combining of reactive components.

ink train

The group of rollers and associated devices that carry the ink from the ink fountain to the plate cylinder in the lithographic and letterpress printing methods. Ink trains normally are used with paste-type inks (for example, as used on a lithographic press) and meter the ink by repeatedly splitting and combining the flow.

ink, transparent

An ink that is transparent rather than opaque. Process printing inks and most printing inks for paper are transparent.

ink, ultraviolet

An ink or varnish that is cured or solidified by the action of ultraviolet (UV) light. UV inks are typically 100% solids.

ink vehicle

An ink’s resinous components that remain after all volatiles are driven off, and which serve to bind pigment particles to each other and to adhere the ink composition to the substrate.

intercharacter gap

In bar-code symbologies such as Code 39, each character is printed independently of other characters in the code. Each character is separated from another by the intercharacter gap, a space that is not a part of the encoded character. More complex codes such as UPC and Code 128 don’t use intercharacter gaps since both bars and spaces are a part of the encoded information.


The contact area between two materials.

interference layer

Materials such as process oils that are present in minute quantities on the surfaces of materials intended to be adhesively bonded or printed. Normally not visible to the eye, such layers can interfere with the formation of a strong adhesive bond with the substrate.


To insert separate sheets of paper or other sheet material between stacked product sheets in order to facilitate handling, prevent blocking, or reduce abrasion and smudging.

interleaved 2 of 5

A machine-readable bar code that uses both bars and spaces to encode a number. Each character is represented by five elements; five bars or five spaces. Each bar and space pattern can encode one character in the bars and one character in the spaces. (For this reason, the code always must have an even number of characters). Interleaved 2 of 5 is a continuous code indicating that there are no intercharacter gaps separating characters.

internal bond strength

(a) When used in reference to a coating or adhesive, the attraction of constituent molecules to each other. The material’s cohesive strength. See cohesion. (b) The bond between fibers or between fiber layers or plies in a sheet of paper.

International Organization for Standardization

The organization, with headquarters in Geneva, Switzerland, is made up of national standards bodies from countries through- out the world. Its objectives are: 1) To facilitate the exchange of goods and services through the development of internationally accepted standards. 2) To provide the machinery for the development of such international standards. 3) To coordinate the national standards of its members. 4) To issue standards recommendations for voluntary acceptance by its members. 5) To provide for exchange of information among the members concerning international standards of work. 6) To cooperate with other international organizations concerned with related problems. Often referred to as ISO, the Greek word for equal.


Ionomers are copolymers of polyethylene and methacrylic acid, further modified by the inclusion of sodium or zinc ions. Ionomers are highly resistant to greases, seal reliably over a broad heat-sealing range, will seal through contaminants, and provide good bonding to aluminum foil. Heavier gauge ionomer films are used for skin packaging. Most often known by Du Pont’s trade name, Surlyn.


A term used to indicate the property of exhibiting prismatic colors.


A prepress proofing system similar in operation to a large ink- jet printer. The digital image is sent to the printer rather than using mechanical film separations. It is a fast proofing system and can be printed on the substrate to be used. However, the image is created using lines rather than halftone screens and the colors are based on the CMYK system, so that matching to the final printed copy has some limitations.


Bombardment with various subatomic particles such as alpha, beta, or gamma rays. Irradiation can be used to initiate polymerization and cross-linking in plastics. Cross-linking in thermoplastics imparts higher density, higher softening temperatures, lower dielectric loss, and improved chemical resistance. Gamma irradiation also is used to eliminate microorganisms from foods, medical supplies, and packaging materials. The ripening, spoilage, germination, and other characteristics of various produce items also can be affected by irradiation treatment. Treatment of consumable foods by gamma irradiation is strictly controlled by national laws in most countries. The most widely used radiation sources are radioisotopes such as cobalt-60. See radiation, gamma.

Ishihara chart

A chart of illustrations composed of varicolored spots arranged so that specific patterns (usually digits or paths) can be seen by an observer having normal color vision. Observers who cannot detect red, blue, or green primary colors will not be able to see some or all of the patterns. Good color vision is essential for anyone involved in color matching.


See International Organization for Standardization.

ISO 14000

A voluntary international standard providing guidance for environmental management systems. The completed 14000 series includes guidelines for environmental management, life- cycle assessment and labeling.

ISO 9000

ISO 9000 protocol is an international set of documents written by members of an International Standards Organization technical committee. Its primary purpose is to harmonize the large number of national and international standards in existence. This series is intended to be driven by market and customer needs. ISO 9001, 9002 and 9003 provide quality assurance models appropriate to different enterprises. Management and selection guidelines are provided in ISO 9000 and 9004.


A process, study, or measurement that is conducted at a single temperature.


A letter style where letters slant, as distinct from vertical or upright alignment. Used to provide differentiation within the text.


Reciprocating metal plates designed to clamp around a material. Heat-sealing jaws for example are heated plates that press and fuse to thermoplastic surface together to form a seal.

J film, J-film

A plastic film with a portion of its width continuously folded in along one edge. If the folded-in portion is exactly half the film’s width, the film is referred to as C-film or U-film.


The thickening of ink or other liquid which cannot be reversed by stirring.

jelly gum

A modified starch adhesive produced by treating starch with alkali and then neutralizing with an acid. A typical jelly gum is about 40% solids, has very high viscosity and very high tack strength. Jelly gums were largely used as pick-up adhesives for can and bottle labelers, but have been largely displaced by newer synthetic adhesive formulations.


The blackness or intensity of black or near-black surfaces.


To intermittently operate a machine for short time and distance increments of substrate travel. Inching.

joint, adhesive

A joint made between two substrates using an adhesive. That part of an assembly that comprises the adhesive and the adhered parts.

joint, lap

A joint made by overlapping the ends of two substrates.

joint, solvent-cement

A joint made by applying a solvent between the surfaces to be bonded and relying in part on the dissolving and subsequent drying of the dissolved plastic substrate to form a continuous bond. Poly(vinyl chloride) and polystyrene are two common packaging plastics that can be bonded this way.

joint, starved

An adhesive joint that does not have has enough applied adhesive to completely cover the available surface area and produce a satisfactory bond.

just-in-time (JIT)

A manufacturing philosophy where the storage of work in progress is eliminated or reduced to an insignificant minimum. JIT eliminates the need for warehousing and further reduces cost by eliminating inventory expenses. According to JIT, multistage systems as found on packaging lines should be “pull” (produce only in response to demand) and not “push” (produce as long as there is raw material to be processed).


Letter or word spacing the characters on each line so the type will line up vertically on the left, right, or both.


(a) Abbreviation for kilo, meaning one thousand. (b) Abbreviation for the Kelvin temperature scale. (c) In color discussions, it represents key color.

kauri-butanol value

A measurement of the solvent power of a hydrocarbon solvent, abbreviated as the KB value.

KB value

See kauri-butanol value.


The precipitation of a portion of an ink or coating.


A prefix meaning 1000. Typically abbreviated as K. The word kilo should not be used as an abbreviation for kilogram.

kilogram (kg)

A metric measurement equivalent to 1000 grams, equal to 2.2046 pounds. The word kilo alone should not be used as an abbreviation for kilogram.


Unit of pressure. One kilopascal (kPa) equals 1000 pascals. Standard atmosphere equals 101.325 kPa. See pascal.

kiss-roll coating

A method of applying a coating to a substrate where a roll with a metered amount of coating is brought into contact with the substrate. At the point of contact, the coating material splits, with part transferring to the substrate and part remaining on the roll.


A pattern applied to a metal roll by mechanical means.


(a) A term derived from a German word meaning strength, applied to pulp, paper, or paperboard produced from virgin wood fibers extracted by the alkaline sulfate process. (b) kraft, natural: Unbleached kraft pulp, paper, or board. Unbleached kraft has a light brown appearance.

kraft process

The extraction of cellulose fiber from the parent wood mass by dissolving the binding lignins with alkaline sulfate chemicals. The kraft process, when used with long-fiber softwoods yields the strongest of the wood-based papers.

(a) The absolute temperature scale; the Celsius temperature plus 273 degrees. (b) The unit of measurement for color of illumination. For example, 5,000 Kelvin (K), used as a graphic arts illumination standard, is the color emitted by a radiator heated to 5,000 K.

key color

In color reproduction, the black plate or another dark color plate, used to increase contrast of dark tones. Black or another dark color is needed in process printing since no combination of the three process colors can produce a jet black. When the key color is black, it may be called the black printer.


A class of organic compounds containing a carbonyl group (C=O) bound to two other carbon atoms. The simplest ketone, acetone, consists of two methyl groups attached to the carbonyl group. Acetone and methyl ethyl ketone (MEK) are common solvents.


Keylines usually are drawn on a clear dimensionally stable plastic sheet (sometimes called a Mylar, a Du Pont polyester trade name) so that it can be placed over the artwork. A keyline provides graphic departments with the main structure outline (container borders, scores, and so on) and the sizing and placement of graphic elements for a package composition. digital files have replaced keylines in many applications.


Abbreviation for lines per centimetre.


(a) (noun) A paper, plastic, or other material sheet or component that is attached to a container, and on which is printed information and graphics relating to the product. In the instance of containers such as plastic bottles, graphic material printed directly onto the container or article. (b) (verb) The act of applying a label.

label, anvil-cut

Pressure-sensitive labels that have been die-cut through both label and carrier web. The cutting die penetrates the complete label assembly in a steel-to-steel motion. Compared to kiss cut which cuts through the label stock but not the carrier web.

label, butt-cut

Rectilinear pressure-sensitive labels separated by a single knife cut to the release liner.

label, continuous

See label, fanfold.

label, cut

Label that has been cut from press sheets and stacked or bundled for delivery. Individual cut-labels are loose in the stack, and in principle, could become separated and mixed in with labels in another stack. For this reason, cut-labels are not used in the pharmaceutical industry, where a mislabeled product could have serious consequences.

label, cut-in-place (CIP)

A label that is cut from the parent sheet or rollstock at the point of application. Commonly used to describe plastic film labels cut from the parent stock in an in-mold-labeling operation. Since a CIP label is supported by the parent stock almost to the moment it is inserted into the mold, the label material can be significantly thinner than that used for a precut label. See labeling, in-mold.

label, die-cut

Shaped labels, commonly spot and wraparound, that have been cut from the parent sheet with a shaped die in a die- cutting machine. (Square or rectangular labels usually are cut with a guillotine.) Pressure-sensitive labels mounted on a carrier web are usually die-cut to the level of the carrier sheet surface and the waste matrix may be removed.

label, face-cut

A pressure-sensitive label where the label or face material is cut to the surface of the backing or carrier material. See also kiss cut.

label heat seal, label, heat-activated

A label coated with an adhesive that can be activated by heat just before or as it is applied.

label, heat-transfer

Labels printed with thermoplastic inks on a web from which they are transferred to containers by application of heat as they contact the container surface. Also a label applied to a bottle by transferring the label, preprinted on a substrate, to the bottle surface using heat to activate a preapplied adhesive.

label, holographic

A decorating technique where a number of images can be overlaid, each of which can be seen only from a specific angle. The image can be made to appear to move or change as the angle of viewing changes.

label, pressure-sensitive (PS label)

A label, precoated with a pressure-sensitive adhesive, which requires only a brief application of pressure to effect a bond. PS labels usually are adhered to a release paper carrier.

label, primary

The label that provides the main product identification and that carries the legal statements such as the generic product name and quantity statements. Secondary labels are other labels whose purpose is mainly supportive. They may carry use information, ingredient lists, promotional material, or other copy. Sometimes referred to as a prime label.

label, print/apply

A labeling system where the label is printed at the point of labeling. Print/apply labeling is used for applying variable information such as ingredient lists, compliance information, and various identification codes. A print/apply labeler can be used to provide a custom appearance to a stock item or to identify size, flavor, color, and so on for similar products that come in a variety of minor variations.

label, roll

Labels supplied in roll form rather than as cut label stock.

label, self-adhesive

See label, pressure-sensitive.

label, shrink

A plastic sleeve that is dropped over the container and shrunk on by heat. Graphics applied to such a label must be distorted during printing in order to be legible after shrinking. Poly(vinyl chloride, polystyrene, polypropylene and poly(ethylene terephthalate) are common heat shrink label materials.

label, shrink-contour

A plastic label applied as a sleeve that when subjected to heat, shrinks to conform to the contours of the container.

label, sleeve

A decorated, plastic sleeve that fits over and on plastic bottles. Sleeve labels, typically made from polyethylene, are heat-shrinkable, and may be held in place by raised ridges above and below the label, or shrunk to conform to a shape that will hold them in place.

label, spot

(a) Any label that does not cover the entire panel available for labeling. For example, a can label that only wraps partway around the can. (b) A printed paper sheet covering a portion of the surface of a corrugated box. May cover a portion of one panel, a full panel, or several panels of the box.

label, wraparound

A label that wraps around the container and overlaps itself. Some wraparound labels are adhesively bonded to the container. In instances where the geometry of the container will hold the label in position, the label may be bonded to itself at the overlap.

labeler, roll-through

A labeling machine for round containers where a leading edge of a label is affixed to the container with a pick-up adhesive and then wraps around the container as the container is rolled between two pressure belts.

labeler, rotary

A labeling machine where the container to be labeled is introduced onto a stage located on a rotating turret. The label is picked up and applied during rotation around the turret. Rotary labelers are capable of exceptionally high speeds. Also labeler, turret.

labeler, straight-line

A fully automatic labeling machine in which containers travel through and discharge in a single straight line. Labels can be applied on both sides of the container.

labeler, tamp-blow

A pressure-sensitive labeling method where an air-jet is used to apply thin film labels to the container.

LABstar value

See color value, CIE.


A type of coating, applied as a liquid, that sets or dries entirely by evaporation. Varnishes set or dry partly by evaporation and partly by chemical reactions such as oxidation or polymerization.

lacquer, heat-seal

A lacquer that when applied to a substrate and dried, is capable of softening under heat and can be sealed to itself or other surface.

ladder, heat-seal

A series of heat-seal tests done over a range of temperatures to determine the optimum heat-seal temperature. Typically, the strength of a heat-seal goes up as temperature is increased until it reaches a maximum value. At this point the heat-seal medium becomes fluid enough to be squeezed out of the seal area and heat-seal strength starts to decline.


A depression or dishing in the surface of a rubber plate.


The adhesive material used to join two substrates, for example, paper, plastic, or foil, in the manufacture of a laminated structure.


(a) (noun) A product made by bonding together two or more layers of material. (b) (verb) To unite layers of material to produce a multilayer material. See also laminated material.

laminate, cross

A laminate in which some of the layers of material are oriented at right angles to the remaining layers with respect to the grain or strongest direction in tension.

laminate, paper/foil

A laminated material composed of aluminum foil joined to paper with an adhesive. Sometimes referred to as a supported foil.

laminate, parallel

A laminate in which all the layers of material are oriented approximately parallel with respect to grain or strongest direction in tension. See also laminate, cross.

laminated material

A material composed of multiple layers of different materials, joined together to make a single sheet. The component layers may be applied coatings or other sheet materials bonded to a base material with adhesives. The objective is to combine materials having specific desired properties to create a new material with a combination of properties not available from any single material.

laminating techniques

Wet laminating joins two or more webs with aqueous or solvent-based adhesives, which are driven off after joining. Dry bond laminating applies adhesive to one of the webs. After drying or curing, webs are joined with heat and/or pressure. Other common laminating techniques are extrusion and hot-melt in which the adhesive or bonding material is introduced in hot liquid form and the bond is effected when it solidifies.


An acronym for light amplification by stimulated emission of radiation. An intense narrow-band light beam used in computer-controlled imaging and printing plate making processes, various cutting applications and bar-code scanning.

laser ablation mask (LAM)

See ablation.

laser marking

A method of printing or coding that uses a laser to produce a mark on the substrate. The surface to be marked must have suitable surface characteristics. The mark produced may be a result of carbonization, changing the color of the substrate or a component in the substrate, modification of the surface finish, scribing a groove in the substrate or any combination of these. Plastics such as poly(vinyl chloride), and poly(ethylene terephthalate) are relatively easy to mark whereas polyethylene, polypropylene and other polyolefins may require additives to make them receptive to the laser.

laser scanner

An optical reading device that uses a low-energy laser light beam to illuminate a code.


(a) A process of plying layers of flexible stock such as paper, foils and plastic films to a produce a single multi-layered sheet of a given thickness. (b) (noun)The final product.

lamination, extrusion

Preparation of a lamination by extrusion coating a melt onto a base material while simultaneously pressing the coated stock against a second material, and then cooling rapidly to establish the bond.

lamination, wax

A laminate in which wax has been used to join two substrates. Wax is economical but can have poor performance properties at other than ambient temperatures. It is used primarily in noncritical laminations such as those serving a decorative function.


A machine or device that combines plies of material into one multilayer structure using various bonding agents.


The sealing surface of a glass or plastic bottle.


The part of a material that covers or overlaps another part. In packaging, a lap usually occurs where two sheet materials are bonded together.

lap thickness

The dimension measured perpendicular to the layers at the overlap of a lap seam.

lap, open

A lap that has failed to make a complete seal.

lap seal

One of the two most common pouch seals. A lap seal overlaps the material for the distance required by the seal and creates the seal, usually by heat sealing. During sealing, the inside of the laminate must be able to seal to the outside, requiring that both sides of the laminate be heat sealable. The lap seal is generally more aesthetically pleasing and uses less material than the fin seal. See fin seal.

laser, helium

The most common type of laser used in bar-code scanners.


A fine particle size polymer resin, emulsified and dispersed in water as might be used in adhesives or coatings.


A characteristic that allows a material to lay out flat with little or no tendency to curl. Such materials are described as having good lay-flat, an important characteristic for many machine operations and for applications such as labeling.


Preliminary arrangement showing position, sizes, color, and other details of the final design.


See life-cycle assessment.


See life-cycle management.


Method of determining the toxicity level of a substance. LD50, the median lethal dose, is the dosage of a toxic substance at which 50% of the test animals die. Acute toxicity levels provide a benchmark on which to judge substances and appropriate handling and packaging procedures. Generally 50 milligrams per kilogram of body weight is regarded as being highly toxic. The packaging of toxic substances is governed by national and international regulations.


See polyethylene, low-density.


The vertical spacing between lines of type. It is measured in points or point units but is referred to as “leading” or a given number of lead points.


The overlapping and orientation of thin, flat pigment flakes. For example, aluminum, bronze, powders, or mica pigments, which give an overlapping or shingle-roof-effect coating surface.

leak, channel

A defect in a sealed flexible plastic pouch where leakage occurs along a channel across the heat seal area. Wrinkles in the plastic film or contamination across the seal area are common causes of channel leaks.


A package that is leaking its contents.


See lower explosion limit.


The dimension in the direction of travel through a machine.


A printing process using relief plates similar to flexography. Unlike fluid flexographic inks that are metered with an anilox roll, letterpress inks are viscous pastes metered by roller trains.


A term sometimes used for offset letterpress printing in which the letterpress plate prints against an offset blanket instead of directly against the substrate.


A coating that flows out evenly to form a continuous film free of surface irregularities is said to level well.


General Electric’s trademark for polycarbonate products.


See lidstock.


Material or stock used to form a lid. More specifically, flat sheet material that can be heat-sealed or otherwise bonded over the open ends of tubs and cups for dairy products, thermoforms for single-serving condiments and pharmaceutical blister cards.

life-cycle assessment(LCA)

A process or tool for evaluating the environmental attributes associated with a product, process, or service. LCA includes all impacts along the entire continuum of a product’s life (i.e., from cradle to grave, earth to earth).

life-cycle management (LCM)

The management of an activity in a manner that takes into account the total environmental impact of a product or service. LCM considers the environmental impact of all inputs and consequences from the point of origin or production to the steps necessary for final proper disposal. Life-cycle assessment (LCA) and product stewardship are key components of LCM.

light box

A viewing box used in the graphic arts industry for comparing colors. Light boxes have standardized light sources, usually specified in color temperature. Most color comparison work is done at 5,000 degrees K.


Able to retain its color when exposed to light. Light stable.

light, infrared

See infrared.

light pen

A small handheld scanning device used to read bar codes. Also a wand scanner.

light reflection

The light, striking an object, which is turned back. The opposite of absorption.

light resistant, light resistance

The ability of material to withstand exposure to light (usually sunlight or the ultraviolet part of the light spectrum) without change of color or loss of physical and/or chemical properties.

light, ultraviolet

Generally fluorescent tubes that emit ultraviolet light rather than normal fluorescent or incandescent light.

limiting quality level (LQL)

For the purposes of acceptance sampling, the percentage or proportion of variant units in a batch or lot for which the consumer wishes the probability of acceptance to be restricted to.


(a) (noun) A series of machines and equipment sufficient for the conversion of materials or for their packaging into the product of sales; hence also (b) The type of product turned out by a production line. (c) (verb) To apply a lining or coating to a material or container, by painting, pasting, spraying, etc.

line art

An illustration composed of solid blocks of color with no

(a) Generally any liner or non-adhered material that separates a product within a container from the actual walls of the container. (b) One of the outer surfaces of a finished laminated or coated stock or paperboard. (c) An outside layer of a cylinder type paperboard. See also closure liner, and bag liner.


A kraft paperboard, frequently called liner, used on either one or two sides of fluted medium paper to manufacture corrugated board.

lines per centimetre

Lines per centimetre of screen ruling. The metric equivalent of lines per inch. Abbreviated l/cm.

lines per inch (lpi)

See screen.


A form of halftone composed of lines instead of dots.


(a) Any release of fibers from the surface of uncoated papers. (b) The removal of poorly bonded fibers from paper surfaces during printing causing the accumulation of fibers on press areas such as blankets, plates, rollers, and ink fountain.


That part of one face of a flat or square paper or film bag or pouch extending beyond the opposite face.

line color

A specified color (for example, one chosen from a PMS color book) other than a process color. Also known as a spot color.

line copy

See copy.

line growth

The growth of a printed line (gain) as a result of pressure between the printing plate and the substrate.

line width reduction (LWR)

The reduction of the line width of bar code bars in order to compensate for gain in the printing process. The amount of reduction will depend on the printing process and the characteristics of the individual press.


The quality of an input-output relationship in which there is direct proportionality.

linear thermal expansion

The fractional change in length of a material for a unit change in temperature expressed as inch/inch degrees F or as centimetre/centimetre degrees C per ASTM D 696.

liquid, Newtonian

A liquid is called Newtonian if its viscosity is unaffected by the kind and magnitude of motion or agitation to which it may be subjected, as long as the temperature remains constant. Water and mineral oil are examples of a Newtonian liquid.


See printing, lithography.


See printing, lithography.


An irreversible increase in the body or viscosity of an ink as a result of gelation or other chemical change.


See polyethylene, linear low-density.

load cell

A device that produces an output signal proportional to the applied load. Direct weight readings can be made when the output is calibrated to a mass scale.

load deflection

The difference in position of some point in a body between a non-loaded and an externally loaded condition.


(a) The name of a company or product in a design used as a trademark in advertising. (b) logo: Abbreviation or trade jargon for logotype.


A fluid adhesive or ink that has high tack and strings out when drawn apart between thumb and forefinger. Opposite of short.


The appearance of a paper when viewed by transmitted light, revealing the texture or formation.

loose roll

A roll that has been wound with insufficient tension or pressure. Loose rolls are prone to telescoping.


A lot refers to all the product made during a single run on a piece of equipment. A run may last for minutes, hours, or even days, but when it is stopped and the equipment or ingredients are altered to produce something else, the production of that lot is complete.

lot number

The identifying number assigned to a lot or batch of product.

lower explosion limit (LEL)

Lower explosion limit; the lowest concentration of combustible vapor in air that will explode.

low temperature flexibility

The flexibility of a film or laminate at sub freezing temperatures.


Lines per inch.


See limiting quality level.


The quality of shining with reflected light. Does not necessarily imply gloss. See gloss.


See line width reduction.


M represents 1000 in Roman numerals. Still used to designate this number in some parts of the packaging industry, for example, to represent 1000 sheets of paper. The basis weight of linerboard in inch/pound units is given in pounds per M, meaning pounds per 1000 square feet.

machine direction (MD)

The direction parallel to a material’s flow through a machine. Flow direction through a machine may impart directional properties to a material. For example, paper acquires a directionality during manufacture known as machine direction (parallel to the paper flow) and cross direction (perpendicular to the paper flow through the machine).


A rack or holding device on a machine holding a number of items or package components ready for insertion into the production process. For example, a magazine holding a supply of labels on a labeling machine.

magnetic ink character recognition (MICR)

The process of machine-reading characters by means of magnetic sensing.


Material that has been manufactured and is being held for release to the customer.

make-ready, makeready

(a) The setup or preparation of a machine for production. For example, the make-ready of a printing press would include mounting printing plates, charging ink fountains, threading the material to be printed, trial passes to register printing stations, and other activities required to prepare the press before a full production run can be made. (b) Materials used in this preparation.


(a) In plastic extrusion, the solid cylindrical part of the die that forms tubing or pipe. (b) A shaft upon which cylinders or other devices are mounted. (c) The core around which paper, or other materials are wound to form tubular shapes. Mandrels are used to form convolute and spiral-wound composite can bodies. The mandrel determines the final internal diameter and shape of the tube.

meal, ready to eat (MRE) 73 subjected to rubbing, scuffing, scratching, and other abrasive



Any process in which numbers, letters, or other decorations are applied to an item or substrate for purposes of decoration or identification. Usually done apart from or in addition to conventional printing.

mask, masking

(a) In color separation photography, an intermediate photo- graphic negative or positive used in color correction. (b) In offset lithography, opaque material used to protect open or selected areas of a printing plate during exposure. (c) Covering of openings in parts of assemblies to prevent entrance of dirt.

mass tone

The color of an ink in bulk.


A term used in the plastics industry for concentrates containing high percentages of pigments and/or other additives to be added in small amounts to the plastic during processing. Also known as color concentrate.


A prepress proofing system marketed by Fuji. Matchprint is an analog system that produces the proof using photonegative color separations. The colors are exposed onto clear film and the individual sheets are then laminated together and over the stock to be used. The number of colors available for film development is not as extensive as for proofs made by the Cromalin method. See also Color Key and iris.

Material Safety Data Sheet (MSDS)

A document describing all pertinent information regarding safety and health hazards that might be associated with a product, as well as precautions and protection measures.


A component in the manufacture of rubber printing plates. An uncured phenolic plastic material is pressed into close conformity with an engraved or etched metal plate holding the pattern to be printed. Uncured rubber is then pressed into the cured phenolic plastic matrix and the pattern is transferred to the rubber.


See polyethylene and polyethylene, medium-density.

meal, ready to eat (MRE)

The military term for a retort pouch. See pouch, retortable.

manufacturer’s code

The part of a universal product code number assigned to the manufacturer by the governing authority, for example, The Uniform Code Council, and which is unique to that company.

mar resistance

Ability to retain a satisfactory surface appearance when

mechanical art

A layout prepared as an original for photomechanical reproduction. Mechanical art techniques have been largely replaced by computer-generated production.


A prefix meaning “one million.” Therefore, “one megabyte” equals a million bytes of data. As computers become ever more powerful, two additional prefixes that have begun to be used are “giga,” meaning “one billion,” and “tera,” meaning “one trillion.” Both are U.S. designations, containing 9 and 12 zeros, respectively.


See methyl ethyl ketone.


A thermosetting plastic from the amino-resin family made by reacting melamine with formaldehyde.


A material normally solid at room temperature that has been heated to a molten condition.

melt flow rate (MFR)

The rate of extrusion of a molten polymer through a die of specified dimensions and under specified conditions of temperature and loading. ASTM D 1238 expresses melt flow rate as the amount of polymer in grams that will flow through the prescribed orifice under the prescribed conditions in 10 minutes. See extrusion plastometer.

melt index

A depreciated term for melt flow rate. See melt flow rate.

melt strength

The strength of a plastic while in the molten state. This property is important when when drawing extrudates from dies, as in casting film, and when sheet thermoforming. It is also important when a plastic film is reheated for shrink- packaging.


The change from the solid to the liquid state. Also the softening of harder compounds.

melting point

The temperature at which the transition from solid to liquid occurs in pure, simple compounds. The point is easily recognizable by a distinct phase change. Polymers are large molecules and are usually broad mixtures of homologs. Melting occurs over a substantial temperature range, the shorter chains melting first and with rising temperature, the longer ones later. Amorphous polymers have no distinctive, visible melt point but rather progress through a series of increasingly softer stages until they begin to flow. Crystalline polymers have distinct melting ranges that may be broad or narrow depending on the degree of crystallinity of the polymers.


A thin, soft, pliable sheet or layer of animal or vegetable material or thin plastic.


The tendency of a plastic article to revert in dimensions to a size previously existing at some stage in its manufacture. For example, a film that has been oriented by hot stretching and quickly chilled while under tension, will, when reheated, tend to revert to its original pre-stretched size due to its memory. Different plastics possess varying degrees of this characteristic. The degree of memory retained by a plastic is largely dependent on its thermal history and processing conditions.


Derived from the Greek meros, meaning a part or unit. The mer is the repeating structural unit of a polymer. Saving a small correction for end groups, the molecular weight of a polymer chain equals the mer weight times the degree of polymerization. Dimers, trimers, tetramers, oligomers, and polymers contain two, three, four, several, and many mer units, respectively.


A microorganism that prefers ambient temperatures for propagation.


Applying a thin coating of metal to a nonmetallic surface by chemical deposition or by exposing the surface to vaporized metal in a vacuum chamber. In packaging most metallizing is done in a vacuum chamber using aluminum. See metallizing, vacuum and susceptor.

metallizing, vacuum

The deposition, in a vacuum chamber, of vaporized aluminum molecules over the surface of a film or paper substrate. Metallizing provides a lustrous metallic appearance and when applied to plastic film, improves gas and light barrier properties. Metallized films are also used to dissipate static electrical charges, reflect radiant heat and for microwavable susceptor packaging.


Polymers such as metallocene polyethylene (mPE) and polypropylene (mPP) are produced using a metallocene catalyst. The resulting resins have unique chain structures and narrower molecular weight ranges than similar polymers produced using conventional catalysts.


The condition when two surfaces appear to be the same color under one light source but different under another light source. For example, two colors might look identical viewed under an incandescent light source, but different under outdoor daylight conditions.


A temporary state of structure in a plastic, such as a crystal- line plastic in which the final crystallinity is attained after passage of hours or days following molding. No physical or mechanical tests should be made while the test material is in a metastable condition (unless data regarding that condition are desired).


A method of driving the polymerization reaction that produces poly(ethylene terephthalate) backwards (depolymerizing) and reverting the polymer back into its starting monomers. The monomers can be purified, eliminating any contaminants, and the monomers repolymerized back to virgin poly(ethylene terephthalate).


The sequence and manner in which events are made to occur. The logical thinking process to achieve an end result. Precise and proven test and evaluation methodologies are critical to produce repeatable and precise data.

methyl ethyl ketone (MEK)

A relatively fast drying, highly flammable organic solvent of the ketone family. Good solvent for nitrocellulose and vinyl lacquers. Small amounts will swell Buna N plates, larger amounts will swell natural rubber. Boiling point, 79.5oC (175oF); flash point, -8oC (24oF).


A metric unit of length. The correct spelling of “meter”, reflecting SI usage and ASTM standards.

metric system

Any of several decimal systems of weights and measures that use the metre, kilogram, and second as basic units. While all are based on the decimal system, they vary somewhat on the choice of base values. Globally the preferred system is that described as the SI system not metric or SI metric.


An irregular, random dot halftone.



A metric prefix meaning one-millionth. Therefore, 10 microseconds equals 10 millionths (10/1,000,000) or one hundred- thousandth (1/100,000) of a second. See milli and nano.


See bacteria.


The study of microorganisms. Study of drugs, cosmetics, and food, using microbiological methods is critical in determining quality and safety.


A term used by climatologists to designate the climate of a small, local area. The term has come into use to describe the “climate” within a package and includes temperature, relative humidity, and chemical composition of the gases within the package.


(a) Having its constituent crystalline grains so small as to be visible only by microscope. (b) Describes certain highly crystallized paraffin wax products.


A common though depreciated term for micrometre. One millimetre = 1000 micrometres. (25.4 micrometres = 0.001 inch).


Minute holes deliberately introduced into (usually) flexible packaging substrates for those applications where a definite level of permeability is required. The holes can be produced by electrical discharge. Micro-perforated films could be used for packaging of fresh produce.


A radio wave between 0.1 and 100 centimetres in wavelength or 1 to 100 gigahertz. Those selected for use in microwave ovens excite movement in water molecules with a corresponding heating effect.


A material that is not significantly heated or changed by the direct action of high-frequency waves generated by micro- wave ovens and that withstands repeated heating by the foods contained within without warping, shrinking, or staining.


All areas of a print that is intermediate in tone between highlight and shadow. An area with 25 to 75% of the surface covered by ink.


The transfer of a component of a material to a contacting material. In packaging this is often the undesired movement of a component of the packaging material into the product contained, or the loss of a desirable product component into the packaging material itself. The latter is also referred to as “scalping.” See also plasticizer migration.


A unit of measure derived from the inch/pound system. One mil = 0.001 inch. Gradually being replaced by micrometre (micron). 1 mil = 25.4 micrometres, usually rounded to 25 micrometres.


A usage factor that refers to the amount of ink or other coating material used to cover a specified surface area.


In project planning, a key network event that is of major significance in achieving the program, project, or contract objectives.

military packaging

The materials and methods or procedures prescribed in federal/military specifications, standards, drawings, or other authorized documents, which are designed to provide the degree of packaging protection determined necessary to prevent damage and deterioration during worldwide distribution of material.

military specification (Mil-Spec)

Specifications primarily for military use and military procurement. Although they may be used by other government agencies; the requirements are predicated on military needs.


A prefix meaning one-thousandth.


Equivalent to 0.001 metre and 0.0394 inch. Abbreviated mm.


A unit of viscosity measurement being 1/1000 of a poise.

mineral spirits

A solvent composed of petroleum hydrocarbon distillates.

minimalistic packaging

Describes packaging that has been reduced to the absolute minimum needed to fulfill its functions.


See polystyrene, medium-impact.


Two materials that are mutually soluble are said to be miscible.


Any condition where the data recorded by a character- recognition system such as a UPC reader does not agree with the encoded data.


A mist or fog of tiny droplets of ink thrown off the press by the rollers or plates. Flying ink. See flying.


metallocene; polyethylene linear low-density. mm See millimetre.


Ease of flow of a liquid or viscous substance, such as an adhesive. The reciprocal of viscosity. See fluidity.

mock-up, comprehensive

A finished or partly finished model. A physical sample with semifinished or conceptual artwork for preproduction evaluation. Comprehensive mock-ups are sometimes used to create promotional and advertising material well in advance of the actual product being available.

modified-atmosphere packaging (MAP)

A packaging method in which the atmosphere contained within a package has been changed to contain carbon dioxide, oxygen, and nitrogen in proportions different from normal air, in order to increase shelf life. In most instances, oxygen is reduced or eliminated except where anaerobic bacteria may be present, where the gas is required to maintain the red color of meat, and for respiring produce. Carbon dioxide in high concentrations is an effective bacteriostat. However, its high water solubility limits its use in some applications. Nitrogen is an inert, tasteless gas of low water solubility and is used primarily as a replacement for biologically and chemically active oxygen.


Made up of subunits that can be combined in various ways.


A modulus is a measure of a mechanical property of a material, most frequently a stiffness property, for example, compressive modulus, flexural modulus, shear modulus, modulus of elasticity, and modulus of resilience.


Ability of a material to lend itself to bending, folding, creasing, or otherwise conforming to the contour of an object or mold and to retain its acquired shape.

mold proof

Not susceptible to the action of mold growth.

molecular weight, average

Polymers are long, chain-like structures. The number of mer units and therefore the molecular weight in varies from chain to chain. Average molecular weight indicates chain length of the most typical chain in a given plastic; it is neither the longest chain nor the shortest.

monoaxial orientation

See orientation.


A chemical compound that can react with itself or other monomer(s) to form a polymer. The single reactive unit that is polymerized into a polymer molecule.

monomer, residual

Unpolymerized monomer that remains incorporated in a polymer after the polymerization reaction has been completed.


In artwork, several photographs combined to form a composite illustration.


The study of the physical form and structure of a material. This includes a wide range of characteristics, extending from the external size and shape of large particles, to dimensions of crystal lattices. It most often refers to microstructure when addressing polymers.

modulus of elasticity

The ratio, within the elastic limit of the material, of stress to the corresponding strain. (The ratio of the change of a dimension to the force producing the change within the elastic limit of the material.) Expressed as pounds force per square inch or kilograms per square centimetre. (Reference method ASTM 638.) See Young’s modulus of elasticity.

moire’ pattern

The defect that occurs when two screens are overprinted in such a manner as to produce undesirable geometric patterns.

moisture absorption

The pickup of water vapor by a material when exposed to an atmosphere of specified humidity and temperature for a specified time. Different from water absorption, which is the pickup of water when in contact with it in its liquid state.

moisture content

The percentage of water in a material expressed as a percent of the dry product weight.

moisture content, critical

The moisture content of a substance at which physical or chemical deterioration occurs to a degree sufficient to render the substance unusable, unsalable, or unpalatable.

moisture content, equilibrium

The moisture content of a substance at which it will neither gain nor lose moisture in an atmosphere having a given relative humidity.

moisture vapor transmission rate

More accurate and preferred term is water vapor transmission rate (WVTR).

moisture proof

Not affected by moisture. Moisture proof implies a long-term stability in contact with moisture. Products that have improved stability, but are affected over a long term should be regarded as being moisture-resistant.


(a) (noun) The tool set or cavity into which a molten plastic is placed and from which it takes its form. (b) (verb) To shape plastic parts or finished articles by heat and pressure. (c) (noun) A uni- or multicellular plant-like microorganism. Molds cannot produce chlorophyll or carbohydrates and must depend on outside sources for nutrients. Molds form filamentous branching growths called micelia and reproduce by spores. Yeasts are similar organisms that reproduce by budding.


(a) In printing, a random nonuniformity in the visual density, color, or gloss of a print, caused by point-to-point differences of the paper surface as regards its ability to accept and absorb ink. (b) Similarly, a nonuniform visual appearance in other fields, for example, colored plastics.


Spotty or uneven ink application, usually most easily seen and most pronounced in large solid areas. Identifiable by “orange peel” effect.


Alternate spelling for mold/molding.


Process of affixing plates onto a cylinder or base in proper position to register color-to-color or cut-to-print on the blank to be printed.

mounting and proofing machine

A machine for accurately positioning printing plates on the plate cylinder and obtaining proofs for register and impression, off the press. Mounting and proofing may be performed on separate machines, each designed for the single function.


Abbreviation for metallocene polyethylene. See metallocene.


See Material Safety Data Sheet.


Acronym for municipal solid waste.

Mullen burst test

A test procedure that measures the pressure necessary to burst a rubber diaphragm through a specified area of substrate. The Mullen burst test at one time was the principle methodology for characterizing corrugated board. It has been largely replaced by an edge crush test for this purpose but does have other applications.


A package containing a number of other independent packages. For example, a beverage bottle six-pack.

multiwall, multi-wall

Having more than one wall or ply. In the instance of bags, multiwall generally refers to more than two-ply construction, whereas two-ply construction is called duplex or doublewall. See sack, multiwall paper.

Munsell color system

A method for classifying surface color based on a three- dimensional model. The vertical black-to-white dimension is called the color value, the circumferential dimension is the color hue, and the radial dimension is called chroma. See also color value, CIE.


Stands for moisture vapor transmission rate. More accurate and preferred term is water vapor transmission rate (WVTR).


(a) A trademark of the Du Pont Co., Wilmington, Delaware, for a clear, tough polymeric poly(ethylene terephthalate) film. (b) Used in preparing art for printing and keylines because of its mechanical strength and dimensional stability.


A prefix meaning “one billionth.” Many internal computer operations are timed in “nanoseconds.” For even smaller subdivisions, the prefix “pico,” meaning “one trillionth,” is used. Both are U.S. designations, containing nine and 12 zeros, respectively.


One-billionth of a metre, one-thousandth of a micrometre or 10 Angstrom units. The unit of measurement of the wave- length of light.

National Drug Code (NDC)

A code designation give to each drug cleared by the Food and Drug Administration for use.


See New Drug Application.


See National Drug Code.


In film and sheet extrusion, the difference between the width of the extruded web as it leaves the die and the final width of the chilled film or sheet before any edge trimming is done.

neck band

having a high percentage of newspaper recycle. Newsboards may be made with higher quality liners for improved appearance.

newton (N)

The metric unit of force. Equals 4.45 pounds force.


A liquid behavior in which the flow is proportional to the shearing force. The ratio of shearing stress to the rate of shear equals the coefficient of viscosity, which is constant for a Newtonian liquid. With non-Newtonian liquids, the viscosity changes with the rate of shear.


(a) (noun) The point at which two adjacent rotating rolls meet or touch. Material is “nipped” between the rolls, and drawn further into them. (b) (verb) To bring two surfaces together, usually between two rotating rolls.

nitrile resin

Polymers containing high concentrations of nitrile having outstanding barrier properties. Generally the constituents are greater than 60% acrylonitrile along with comonomers such as acrylates, methacrylates, butadiene, and styrene.


A film-former used in flexographic and gravure inks; nitrated cellulose.


Official name or title given to items of material and equipment.


A typical or general value given for purposes of classifying or identification, but not an exact value.

nominal size

The standard size for a bar code symbol. Most codes can be used over a small range of size reductions and enlargements, most commonly between 80 and 120% of the nominal size.

non-fogging film

Film treated so that it does not fog over with condensation.


The property of a material that resists the creation of a bond between adjacent contacting layers.


A departure of a quality characteristic from its intended level or state.

nondestructive testing or inspection

Testing by methods that do not destroy the item, part, or component to determine its suitability for use.


Will not support combustion.

A ring of material such as paper or plastic that is either shrunk or glued around the neck or finish of a container. The purpose may be to provide tamper-evidence, or decorative or to conceal the fill level point on the container.

neck band, tamper-evident

A plastic band that is shrunk in-place around the bottle closure so that it cannot be removed without first damaging the neck band. Poly(vinyl chloride) is one of the more common materials used for this application.


A photographic image on which the image to be printed is clear and the non-image areas are black. A reversed image.


The absence of acid or alkaline activity in a material. The presence of an equal concentration of hydrogen and hydroxyl ions. Materials having a pH of 7.


The addition of chemicals such as buffering agents that will adjust the pH level of a substance to closer to 7.

New Drug Application (NDA)

Submitted to the FDA for each new drug or drug package.


Flow behavior of many liquids, including printing inks and adhesives, in which the flow is not proportional to the shearing force. Flow in which the viscosity changes with stirring or agitation.

nonpolar molecule

A molecule in which the sharing of electrons between the participating atoms is equal, with the result that the molecule has no significant polarity or attraction for other molecules.


A term used to describe machinery designed to operate in an explosive or flammable atmosphere or with explosive or flammable materials. Sparking may be caused by the striking of one piece of ferrous metal against another or by the discharge of static electricity resulting from the rubbing of nonconductive materials against each other. See also explosion-proof.


That portion of a material that does not evaporate at ordinary temperatures.


The opening formed by cutting away a small V-shaped portion of the material.

notch sensitivity

The tendency of a material such as some plastic films to readily propagate a tear from a small initiating notch or incision. For example, a pristine oriented polypropylene film is very difficult to tear but will tear readily if a small incision is cut into the sheet edge. Plastic materials have varying notch sensitivities.

nucleating agent

A chemical substance which, when incorporated in crystal- forming plastics, provides active centers (nuclei) for crystal growth as the melt is cooled. In polypropylene, for example, a higher degree of crystallinity and more uniform crystalline structure is obtained by adding nucleating agents such as adipic or benzoic acid or certain of their metal salts. In some instances, promoting the growth of very small crystal formations can improve the clarity of a crystalline polymer.


A former DuPont trade name for a polyamide polymer. See polyamide.

Occupational Safety and Health Administration (OSHA)A U.S. federal organization responsible for safety in construction sites and plants, based in Washington, D.C.


Acronym for optical character recognition.


An abbreviation for the machine-readable character set described in ANSI Std. X3.17.


An abbreviation for the machine-readable character set described in ANSI Std. X3.49.


The outside diameter of a cylinder, roll, closure, or other circular object.

odor, residual

Any foreign odor retained by a material that may be transferred to the product or be deemed offensive in its own right. In packaging materials, residual odors are commonly associated with incomplete drying or curing of inks, adhesives and coatings.


Un-utilized trim. In flexible packaging, a narrow roll of material when a customer’s order does not call for the full roll width. Sometimes called a butt roll.


An activity that is performed outside of the main production line and that does not stop a production line. For example,

parts and fixtures for a subsequent run might be prepared while the machine is running on the current product. Such off- line preparations reduce the time that a production line is not running.


(a) Transfer of printing inks or coatings from the front surface of one sheet to the back of a contacting sheet or surface. (b) Trade abbreviation for offset lithography.

offset powder

A fine powder dusted between lithographically printed stock to prevent the moist ink on one sheet from offsetting onto the back of the contacting sheet.


Offsets on rolled films and laminates describe nonuniform roll ends characterized by a series of steps (offsets) rather than a square roll end.

oil, essential

A volatile substance that can be detected by the sense of smell and an important component in the perception of flavor or aroma. Also referred to as a sensory active agent (SAC). Essential oils are easily lost or degraded, and their preservation is critical to the value of products such as foods, confections, toothpastes and cosmetic preparations. In some instances, the absorption of external essential oils (contaminants) can be detrimental to the quality of a product. The movement of volatile essential oils is controlled by barrier type packaging.


(a) Unsaturated hydrocarbons containing only carbon and hydrogen atoms, and named after the corresponding saturated hydrocarbon by adding “ene” or “ylene” to the stem. For example: ethylene (from ethane) and propylene (from propane). (b) A polymer whose structure is primarily based on hydrocarbon monomer units (for example, ethylene and propylene).


Related to the sense of smell.


A substance composed of a small unspecified number of monomer units repetitively linked together. Dimers, trimers, and tetramers define the actual number of monomer units in the structure. An oligomer is intermediate between these and a fully developed polymer.


(a) The ability of a material to stop the transmittance of light. Quantified as the amount light transmission. The opacity of a material is based upon the ratio of diffused light reflectance of a material backed with a black body to the diffused reflectance of the same material backed with a white body. The higher the percent of opacity, the more opaque the material is said to be. (Reference ASTM D 589.) (b) In ink, its hiding capabilities.


(a) (adjective) Descriptive of a material or substance that will not transmit light. Opposite of transparent. Materials that are neither opaque nor transparent are best described as translucent.

open time

The time between when an adhesive is applied and when the substrates to be bonded are brought together. Also the time the adhesive remains tacky enough following application to enable a viable joint to be made. See also bonding range.


See polypropylene, oriented.

optical character reader

An instrument or device that is able to scan, recognize, and process a machine-readable code.

optical distortion

Change in appearance of objects viewed through a transparent material.


In the field of chemistry refers to the compounds, containing carbon.


A suspension of finely divided polymer, most commonly poly(vinyl chloride) in a plasticizer, together with a volatile organic liquid. The vinyl organosol can be easily applied to a substrate and subsequently applied heat will fuse the vinyl into a continuous film.


The process of mechanically stretching plastic film or parts in order to produce straightened and aligned molecules. If done in one direction like in the manufacture of plastic strapping and cast film, the material is said to be uni-, or monoaxially, oriented. If done in two directions, the film is biaxially oriented. Orientation markedly improves many physical properties.


An opening; usually suggestive of some level of precision.


The first full rendition that is required to be reproduced using a printing process.


See Occupational Safety and Health Administration.


The diffusion of solvent through a semipermeable membrane separating two miscible solutions and that tends to equalize their concentrations.


Refers to oxygen transmission rate. See permeability.


The release of gas that has been dissolved in a packaging material or product. For example, a product and package might have been purged of oxygen in order to increase shelf life. However, an analysis of the headspace gas may reveal small amounts of oxygen, that may have outgassed from the packaging material or from the product itself.


Supplementary labeling information in the form of a printed leaflet adhered to the outside of a package with adhesive or held in place by an overwrap. The outsert may be a large piece of literature folded so that it forms a compact bundle that can be affixed to the container.

over-the-counter (OTC)

Those pharmaceutical preparations that may be sold without a medical practitioner’s prescription.


(a) In artwork, a transparent covering over the copy where color break, instructions, or corrections are marked. (b) Also, transparent prints which, when placed one on the other, form a composite picture.


A condition where the methods and materials used to package an item exceed the requirements for adequate containment, protection, transport, and sale.


Printing of one impression on top of another, or one material on top of another.

overprinting, multicolor

A technique of overprinting a given number of transparent ink colors to produce additional colors without using halftones.


Items that exceed the number ordered. Because of production uncertainties, manufacturers must calculate on how many pieces will be required to set up each step in the production process and how many will be lost through accidents and other incidents during manufacture.


In packaging, any device applied over the primary closure to hold it firmly in place and/or to supplement its gas barrier.


The modifying hue or tone of a color.


(a) (noun) A wrapper applied over a product, package, carton, box, or other object. (b) (verb) To apply a wrapper over a product.


A chemical reaction involving combination with oxygen to form new compounds.

oxygen-transmission rate

See permeability.

oxygen absorber

Substances that will absorb or react with oxygen. When sealed into a package, they will remove oxygen and eliminate or reduce the possibility of oxidation reactions. The absorbent material can be included in a separate packet or sachet, or may be incorporated into some part of the packaging material itself. Most oxygen scavengers are based on finely divided iron.

oxygen-absorbing sachet

A porous pouch containing an oxygen-absorbing material, that is sealed into packages for the purpose of removing oxygen in the contained atmosphere, thus, preventing degradation processes that require oxygen. See oxygen absorber.

p-s label

See label, pressure-sensitive.


(a) (noun) Denotes the package. (b) (verb) To place objects or materials into a container.

package, packaging

(a)(noun) A form that is intended to contain; protect and preserve; facilitate safe, efficient transport and distribution; and finally communicate information and act to motivate a purchase decision on the part of a consumer. The term “package” is frequently associated with adjectives such as consumer, industrial, hotel/restaurant/institutional, household and industrial chemicals, that define the intended market, or by terms such as distribution, primary, secondary, protective, strip, blister, portion, flexible, rigid, and semirigid, that describe its form, function, material or construction. (b) (verb) To put product into a package.

package engineering

The application of scientific and engineering principles to solving the problem of functional design, formation, filling, closing, and/or preparation for shipment of containers regardless of type or kind, or the enclosed product.

package, primary

The first wrap or containment of a product.

package, secondary

A package or containment of a primary package.

packaging class

The UN has assigned all dangerous goods to one of three packing groups (see packaging group) representing three levels of danger. Dangerous goods are further divided into classes according to the type of danger associated with the product. These are: Class1 Explosives: Class2: Gases: Class 3 Flammable liquids: Class4: Flammable solids: Class5 Oxidizing substances including peroxides: Class6 Poisonous and infectious substances: Class 7: Radioactive materials:

packaging, protective

Packages and packaging components whose prime purpose is to provide protection from physical, biological and chemical degradation during the distribution cycle.

packaging, smart

A packaging system that goes beyond the passive packaging functions of containing, protecting and helping to transport. Such packaging may have incorporated oxygen absorbers, may change color to indicate temperature abuse, or have other interactions with the product or intended purchaser. See also active packaging.

packing group

The UN has assigned all dangerous goods to one of three packing groups: Packing group 1 is intended to apply to materials considered to pose high danger levels, packing group 2 is a medium danger material, while packing group 3, while still dangerous, has been judged to have a lower danger level. See also packaging class.


The collection of colors or shades available to a graphic system or program.


The main face/faces or side/sides of a pouch, carton or other packaging form.

Pantone color

A color selected from the Pantone Matching System. See Pantone Matching system.

Pantone Matching System

A commercial color specifying system commonly used in graphic arts. Pantone Inc. produces books containing color swatches printed on selected substrates. Each color is identified by a Pantone Matching System (PMS) number code. Designers can reference the PMS numbers when calling up different ink colors during discussions with customers, printers, and ink producers. The PMS number code also provides the-ink maker with the formulation details for that color.

paper and paperboard

Sheet material produced by the matting of (usually) cellulose fibers. Paper and paperboard are nonspecific terms that can be related to either material caliper (thickness) or grammage (weight). The International Standards Organization (ISO), states that material weighing more than 250 grams per square metre(51 pounds per 1000 square feet.) shall be known as paperboard. In U.S. practice, material over 300 micrometres (0.012inch) thick is paperboard. The paper industry has few definitive terms. For example, boxboard, cardboard, and cartonboard are all terms used to describe heavier paper stock.

paper brightness

The reflectivity of paper, or paperboard for specified blue light measured under standardized conditions on a particular instrument designed and calibrated for this purpose. Strictly speaking, brightness is not a colorimetric quality. The quality of brightness is related to the quality of the graphic that can be printed. The brighter the paper surface, the more brilliant the graphic. For comparison, newsprint is typically 55 bright while most papers used in packaging range from 78 to 84 bright. Photographic paper can be 100 and higher. Brightness is a paper specifying value.

Class 8 Corrosives: Class 9 packing group.

packaging, industrial

Other dangerous goods. See also

Packaging of goods for commercial and industrial markets rather than retailed consumer goods.

packaging, intelligent

See active packaging and packaging, smart.

paper, clay-coated

A paper or paperboard, the top of which has been coated with a fine clay that produces a printing surface. The clay coating fills in and smoothes any surface irregularities, as well as increasing the surface brightness.

paper, fine

A general term for printing, writing, labeling and cover papers as distinguished from coarse papers such as wrapping papers and other papers not usually printed. Fine papers are normally made up entirely of chemical pulps.

paper, glassine

A supercalendered, smooth, dense, transparent or semitransparent paper manufactured primarily from chemical wood pulps, which have been beaten to secure a high degree of hydration of the stock. Glassine paper is grease resistant, and has a high resistance to the passage of air and many essential oil vapors used as food flavoring. When waxed, lacquered, or laminated, is practically impervious to the transmission of water vapor.

board together or laminating a paper, plastic film, or other sheet material with specific properties to one or two sides.


An inert hydrocarbon wax derivative from crude petroleum. Paraffin waxes of many varieties and melting points are available. Their main uses include the conferring of water resistance, and as a component in hot melt adhesives.

paraffining, cold-water

A process for coating paperboard in which the board or box blanks are immersed in cold water immediately after contact with the hot paraffin, thus preventing penetration, and resulting in a high gloss finish. See cold-water waxing.

paraffining, hot

The process whereby melted wax is allowed to penetrate into paperboard after application. Also known as hot waxing. See paper, waxed.


Describes any drug intended for administration by subcutaneous, intramuscular, or intravenous injection.

particulate food

A food product that contains discrete lumps or particles.


The SI unit of pressure and stress, equal to 1 newton per square metre (N/m2). The pascal (Pa) and its multiples are intended to supersede all other units of force per unit area such as pounds force per square inch and atmospheres. psi x 6.895 = kPa.


A high-viscosity nonflowing adhesive or ink composition with a plastic-like consistency, for example, starch adhesives or lithographic inks.

paste line

The line of adhesive between the two surfaces to be adhered. Also glue line.


A tint or mass tone to which white has been added. When printing a halftone on a white substrate, the white is provide by the substrate itself.


A machine that applies an adhesive to two or more plies of paper material and combines them into a single sheet or board.

paper, pouch

A supercalendered and plastisized, usually highly pliable, kraft paper.

paper recycled

A paper that uses a significant proportion of post-consumer waste as a proportion of its make-up. Repulping of paper-mill in-plant scrap is not considered to be recycling in most jurisdictions. The quality of recycled papers will vary widely depending on the quality of the collected material.

paper, release

A paper that has been coated with a release agent (an anti- adhesive, most commonly silicone or fluoropolymer based) to prevent the formation of a permanent adhesive bond. Release papers are used to hold pressure-sensitive labels and to back certain adhesive tapes.

paper, waxed

A general term applied to paper that has been impregnated or coated with molten wax in a separate converting operation. The paper base is usually a dense glassine or parchment type stock that limits the amount of wax that penetrates completely into the stock. When the wax is impregnated into the paper, the product is referred to as “dry-waxed.” When the wax remains on the paper surface as a coating, it is termed “wet- waxed.”


The heat treatment of product at temperatures typically at about 70oC (158oF). Pasteurization is used where higher temperatures would alter the product, and where the surviving microorganisms are not pathogenic and can be controlled by other means.


The use of adhesive, typically starch- or dextrin-based, to join paper bag and envelope materials.


A microorganism capable of causing sickness or death.


See polyethylene.

peel adhesion

The force required to peel a pressure-sensitive material from a standard test plate at a specified angle and rate.

permanence, permanency

That property ascribed to a material that allows it to resist changes to any or all of its properties over time in its working environment.

permanent set

The change in dimension, expressed as a percentage of the original dimension, by which an elastic material fails to return to its original length after being stretched or compressed for a specified period of time.


The property of a film or package that permits the diffusion of gases and liquids through an essentially continuous film or container. Permeability is approximately the product of the diffusivity times the solubility of the gas or vapor in the material. Permeation rates usually are described as the rate of permeation for a given area, thickness, and time. Because of the wide choice of units, there are many different ways of expressing permeability. Care should be taken when comparing values, that the units of measure are identical. As a general rule, the permeation rate is inversely proportional to a material’s thickness. Doubling the thickness will approximately halve the permeation rate.

permeability, gas

The ability of a solid material to allow a gas or other volatile substance to penetrate and pass through. Materials that will allow significant passage of gases are said to be permeable, while materials that resist or stop the passage of gases are said to offer gas barrier properties. See gas transmission.

permeability, water vapor

The property of a material that permits water vapor to pass through its structure.


The passage of gas, vapor, or liquid molecules through a film or membrane, usually without physically or chemically changing it, except that permeation involves solubility of the vapor in the film. See permeability.

peroxide number

A chemical measure of the degree of oxidation or rancidity of fats and oils.


In package design, a package is often described as if it were a person. The persona of a package should be similar to that of the targeted customer.


peel strength

The stress required to peel apart two adhesive-bonded surfaces.


A seal, coating, or laminate that can be easily pulled apart without tearing the base material(s). Peelable seals may be designed to peel by adhesive failure or cohesive failure.

peghole, peg-hole

A hole made in a package or card so that it can be hung on a projecting hanger for the purposes of display or storage.


See poly(ethylene naphthalate).


(a) Chemical agent added to an adhesive to increase its penetration into the stock. (b) a material that has penetrated into another.


(a) The ability of a liquid (ink) to be absorbed by a substrate. (b) The degree to which the die-cutting knife penetrates into the substrate material during die-cutting.

penetration time

Time required for an adhesive to penetrate into a substrate before it can “set up” or cure.


A series of small holes usually placed to assist in tearing of the perforated product along a predetermined line or to facilitate air removal during bag filling. Materials also may be perforated to allow for the passage of gases.


A numerical scale from 1 to 14 for representing the acidity or alkalinity of an aqueous solution. Seven is neutral. Below 7 indicates increased acidity, above 7 indicates increasing alkalinity. Each unit step indicates a ten-fold increase of acidity or alkalinity. Most meat and fish products have pH values between 6 and 7. Vegetables have values between 5 and 7, and fruits are typically between 3 and 5. Some microorganisms will not propagate at low pH levels, reducing the need for rigorous sterilization of high-acid foods. High acid is generally taken to mean a pH value below 4.5.


A manufactured, processed, or compounded form of a drug.


A material that changes color with light. Used in some printing inks to create novel effects.


Breakdown of a material due to the action of visible or ultraviolet (UV) light. Many materials, including most plastics, tend to absorb high-energy radiation in the UV portion of the spectrum, which causes oxidation, chain cleavage, and other destructive reactions. Generally, photodegradation is undesirable, with the exception of a few instances where photodegradable plastics have an environmental advantage. Additives that act as photoinitiators or photosensitizers usually are added to promote degradation by UV light. However, it is more common to add UV stabilizers to many plastics to delay degradation. Food and pharmaceutical products that are sensitive to UV-initiated degradation usually are packaged in opaque containers or amber glass, which has the property of filtering out most UV light.

photoelectric cell

A cell whose electrical properties are modified by the impingement of light; specifically one that uses the photoelectric effect to produce an electric current. Such cells are used extensively on automatic packaging machinery to register printed designs and for many other purposes. Sometimes referred to as an electric eye.


In flexography, a metal printing plate pattern prepared by a photochemical process, from which the matrix or rubber mold is reproduced.


A chemical that when activated by ultraviolet light starts the chemical reactions, which lead to polymerization in ultraviolet- curable inks, coatings, and adhesives. The photoinitiating chemical acts as a light-activated catalyst.


Pertaining to any platemaking process using photographic negatives or positives exposed onto plates or cylinders covered with a photosensitive coating.


A polymeric compound containing an agent that undergoes a change when exposed to light, proportional to light intensity, so that images can be formed on its surface by a photo- graphic process. A common photopolymer used to make

flexographic printing plates is a viscous liquid in its unexposed state but becomes a rubbery solid when exposed to light and cured. Photopolymers play an important role in the manufacture of printing plates of all types.


In photomechanics, a light-hardened stencil to prevent etching of nonprinting areas on plates. Also called a resist.


A unit of type measure, 1/6 of an inch.

pick, picking

Rupturing of the surface of the substrate being printed. Occurs when ink tack pulling power is greater than the surface strength of the material.

pick resistance

Resistance to picking. See surface strength.


Single or paired plates used to transfer a label or labels from the label magazine to the grip-finger. During the transfer, the label receives a coating of adhesive.


A general term for all colorants, organic and inorganic, natural, and synthetic, that are insoluble in the medium (vehicle) in which they are used. Organic pigments are those that contain carbon as the basic part of the molecule. The inorganic pigments, many of which are based metals and other minerals, contain a metal oxide or salt as the basic part of the molecule. Some of the most highly colored inorganic pigments are oxides and complexes of heavy metals. The use of these is being restricted and/or eliminated since heavy metals are biologically toxic.

pigment, fluorescent

Pigments that absorb radiation of a frequency not visible to the human eye and then emit radiation of a longer frequency that is visible. Perceived as a perceived glowing effect.

pigment, inorganic

Natural or synthetic metallic oxides, sulfides, and other salts, they are outstanding in heat-and-light stability, weather resistance, and migration resistance. Many highly colored inorganic pigments are biological toxic heavy-metal compounds, and their use as colorants in packaging is increasingly being restricted.

pigment, metallic

A class of pigments consisting of thin opaque aluminum flakes or copper flakes and copper alloy flakes (known as bronze pigments). They produce unusual silvery and other metal-like effects when incorporated into inks and plastics.

pigment, organic

Any pigment derived from naturally occurring or synthetic organic substances, characterized by good brightness and brilliance and (usually) transparency. Generally, they are less resistant to chemicals, heat, light, and solvents than inorganic pigments.

pigment, pearlescent

A class of pigments consisting of particles that are essentially transparent crystals of a high refractive index. The optical effect is one of partial reflection from the two sides of each flake. When reflections from parallel plates reinforce each other, the result is a silvery luster. Possible effects range from a moderate enhancement of the normal surface gloss to brilliant highlighting.

pigment, phosphorescent

Generally a pigment containing inorganic sulfide crystals that absorb the energy of incident light then slowly reemit it as radiation of a color specific to each pigment. The phosphorescence gradually dims in darkness but can be renewed by exposure to light.


Addition of pigment.


See pinholing.


(a) Minute holes in thin-gauge aluminum foil caused by the inclusion of gases and other impurities. Pinholing seriously reduces a foil’s barrier properties. (b) Failure of a printed ink to form a complete continuous film; visible in the form of small holes in the printed areas. See hickey.


The smallest part of a digitized image. Resolution of an imaging system. Short for picture element.


See polylactic acid.


Printing from a flat surface as in lithography.


(a) Any material capable of being formed or shaped. (b) A material that contains as an essential ingredient, high to ultrahigh molecular weight organic molecules. The two main plastic classes are thermoplastic and thermosetting, depending on whether the molecules are structurally independent of each other or cross-linked. (c) In modern usage, plastic describes a large number of high-molecular-weight synthetic polymers that can be molded into useful shapes. The terms “plastic” and “polymer” are interchangeable in most discussions. (d) Indicating that the object described is made of or has the properties of a plastic.

plastic flow

Change in dimensions and shape of a material when subjected to external weight or pressure, generally at room or cool temperature. See cold flow and plastic deformation.

plastic, cellular

See plastic, expanded.

plastic, expandable

A plastic in a form to be made cellular by thermal, chemical, or mechanical means. Common plastics used are polystyrene, olefins, and polyurethane. Commonly referred to as expanded or foamed plastic.

plastic, expanded

A plastic that has been made in the form of a foam by expanding it with gases produced by thermal or chemical means. Expanded plastics can be made in closed- or open-cell forms. Most expanded plastics are produced by incorporating a blowing agent that will decompose and release gas, or by the evaporation of a low boiling point liquid. Expanded (cellular) plastics have good insulating properties and their resiliency makes them useful for protective cushioning systems. Most expanded plastics are based on polystyrene, polyurethane, or polyethylene. Synonymous with cellular and foamed plastic.

plastic, flexible

(a) Generally taken to be a plastic whose resin has a modulus of elasticity either in flexure or in tension of less than 70 MPa (10,000 psi) at 23oC and 50% relative humidity (RH). (b) Processed (molded, cast, extruded, drawn, or laminated) plastic that can be bent around a 1-inch in diameter mandrel at 23oC and 50% RH with no plastic deformation or breaking.

plastic, natural

Plastic material to which pigment was not added.

plastic, nonrigid

For purposes of general classification, a plastic that has a modulus of elasticity either in flexure or in tension of not more than 700 kilograms per square centimetre (10,000 psi) at 23oC and 50% RH when tested in accordance with the Method of Test for Stiffness of Plastics by Means of a Cantilever Beam (ASTM D 747), the Method of Test for Tensile Properties of Plastics (ASTM D 638), or the Methods of Test for Tensile Properties of Thin Plastic Sheeting (ASTM D 882).

plastic, open-cell

A cellular or expanded plastic in which interconnected cells predominate.

plastic, rigid

(a) A plastic whose resin has a modulus of elasticity either in flexure or in tension of more than 700 MPa (100,000 psi) at 23oC and 50% relative humidity. (b) Processed plastic, the degree and conditions to which it could be bent around a 1- in.-diameter mandrel; extent not yet determined. (c) As applied to containers, includes plastic bottles, boxes, cans, drums, trays, and components that have definite retained shape and form.

plastic, semirigid

(a) A plastic whose resin has a modulus of elasticity either in flexure or in tension of between 70 and 700 MPa (10,000 and 100,000 psi) at 23oC and 50% relative humidity.


Property of a material that enables it to be continuously deformed without rupture when acted on by a force sufficient to cause flow and allows it to retain its shape after the applied force has been removed. Plasticity, like consistency, is a qualitative term, representing a composite of physical properties. Plasticity may not be defined quantitatively because it is a complex property made up of yield value and mobility, or their equivalent.


To render a material softer, more flexible, and/or more moldable by the addition and intimate blending of a plasticizer. See plasticizer.


A substance incorporated into some plastics to increase flexibility, or extensibility, while reducing elastic modulus. A plasticizer also may reduce melt viscosity and lower the glass- transition temperature. Most plasticizers are nonvolatile organic liquids or low-melting solids (for example dioctyl phthalate, diisooctyl phthalate, and diisodecyl phthalate) that function by reducing the normal intermolecular forces in a resin, thus permitting the macromolecules to slip past one another more freely. Poly(vinyl chloride) is the main user of plasticizers.

plasticizer migration

Undesired movement of the plasticizer from the material into which it has been incorporated to the surface of that plastic or to another adjacent material. See also migration.

plasticizer, internal

An agent incorporated in or copolymerized with a resin during its polymerization to make it softer and more flexible, as opposed to a plasticizer added to the resin during compounding.


Derived from plastic-elastomer. A term used primarily to describe polyolefin polymers incorporating metallocene catalyst technology. The resulting materials are soft, rubber- like thermoplastics with an unusually high elongation.

plate, flexographic

A relief-molded flexible medium, usually rubber, either natural or synthetic, or photopolymer, by which ink is transferred from the anilox roll to the surface to be printed.

plate backing

Material on which the rubber or photopolymer material of a printing plate is mounted for dimensional stability and for attachment of mechanisms for mounting the plate on the plate cylinders.

plate, key

In printing, the single printing plate of a set of color plates that carries the detail and to which the other plates are registered. Black or another dark color are usually selected as the key plates.

plate, lithographic

A metal sheet, usually aluminum, to which the subjects of a design have been photographically or digitally transferred from the original artwork. The sheet prints the design or lettering by offset lithography. A separate plate is required for each printed color.

plate, pattern

The engraving or combination of plates used for making the matrices from which rubber printing plates are made.

plate, rubber

Printing plate made of rubber. Used primarily in flexographic printing.

plate, stripper

In labeling using pressure sensitive label stock, the plate where the label is separated from the matrix or carrier web. A peeler plate.


(a) A flat plate, usually used in reference to a flat plate mounted in a press. See press, platen. (b) A method of die- cutting that uses flat cutting dies as opposed to rotary die- cutting.


An area where a wrapper has been tucked in to take in
surplus material in such a way that there are three thicknesses of the wrap material in the pleat area.


A fixture positioned at the correct angle across the path of material flow to divert or shape it.

plastify, plasticate

(a) To soften by heating. (b) To soften a polymeric material by the addition of a plasticizer.


A suspension of a finely divided vinyl chloride polymer or copolymer in a liquid plasticizer which has little or no tendency to dissolve the resin at ambient temperatures, but which becomes a solvent for the resin when heated. At room temperature, the suspension is very fluid and suitable for casting. At an elevated temperature, the resin is completely dissolved in the plasticizer, forming a homogeneous plastic mass, that when cooled is more or less a flexible solid. A plastisol modified with volatile solvents or diluents that evaporate when heated is an organosol. Other variations include formulations that polymerize to hard solids on heating. Flowed-in liners on lug closures, the compound for providing hermetic seals on can ends, and the thread material on press-on, twist-off closures are plastisols.

polyamide (PA)

Commonly known as nylon. A polymer made by the reaction of a dibasic acid and an amine. There are many dibasic acids and many amines, giving the possibility of many polyamides, few of which are used in packaging. PA is used almost entirely as a film or sheet material in packaging applications. The clear film offers a good oxygen barrier, is particularly tough and abrasion resistant, and can be drawn easily into thermoformed trays. It is, however, a poor moisture barrier, does not heat- seal, and has a cost disadvantage. Its primary usage is for the thermoformed half of luncheon meat and cheese vacuum packs, and in applications that require particular abrasion resistance or toughness (for example, coffee vacuum packs). More recently PA has been incorporated an oxygen barrier layer in multi-layered plastic bottles.

polybutylene (PB)

Semicrystalline polyolefin thermoplastics based on 1-butene, and includes homopolymers and a series of poly(1-butene/ ethylene) copolymers. Used in hot-melt adhesives and sealants.

polycarbonate (PC)

A polymer derived from the reaction of aromatic and aliphatic dihydroxy compounds with phosgene. Characterized by high toughness, exceptional impact strength, and high temperature resistance. Used for large drinking-water bottles, returnable milk bottles, and any application where outstanding impact performance is required. Its current cost limits expansion into most packaging applications.

polychlorotrifluoroethylene (PCTFE or CTFE)

A plastic material characterized by exceptional moisture- and good oxygen-barrier properties as well as good clarity and easy thermoformability. Its cost restricts it mostly to the pharmaceutical industry. Aclar is a trade name for a product based on PCTFE.


A polymer made by the reaction of a dibasic acid and a glycol. There are many dibasic acids and many glycols, giving the possibility of many polyesters, some of which are thermosets and some of which are thermoplastics. Packaging uses a thermoplastic polyester made by the reaction of terephthalic acid and ethylene glycol. The proper name for this product is poly(ethylene terephthalate), abbreviated most commonly as PET. (PET is also a registered trademark of a milk product. To avoid possible confusion, poly(ethylene terephthalate is identified as PETE on plastic identification codes.) See poly(ethylene terephthalate).

polyester, metallized

Poly(ethylene terephthalate)(PET) film on which a minute amount of aluminum has been vacuum-deposited to improve barrier properties, enhance appearance or to produce a heating structure for microwave packaging applications.


A single layer of a multilayer laminate.

ply adhesion

The quality of the bond between two plies of material.


See polymethylpentene.


A nonspecific term used as a unit of measure. In paper thickness measurement, a point = 0.001 inch. In the printer’s unit of measurement, used for designating type sizes, there are 12 points to a pica and 72 points to an inch.

point of difference

In a retail package presentation, those elements that establish the differences or advantages of one product compared to its competitors.

point of purchase display (POP)

Devices and arrangements for presenting a product to the consumer. Point-of-purchase displays can be permanent units or temporary displays prepared only to merchandise the contents of a shipping unit or to promote a product for a defined period of time. Product secondary packaging and distribution containers often are designed with a POP utility, providing increased value to the retailer.

point of sale (POS)

A location where a sales transaction is finalized. For example, the scanning and recording of bar-code data takes place at the POS. Impulse purchase items may be displayed at the POS.


A measure of absolute viscosity. A centipoise is equal to one- hundredth of a poise. The viscosity of water is 1 centipoise.

polar molecule

A molecule in which the sharing of electrons between the participating atoms is unequal, resulting in a molecule having a significant polarity or attraction to other molecules. This type of molecule can be thought of as having the properties of a small magnet.

pollution control equipment

Any equipment or machinery whose purpose is to remove or render less environmentally harmful any solid, liquid or gaseous process products or by-products.


A non-specific term for a polymeric material. Most frequently used to describe polyethylene.

polyethylene (PE)

A polyolefin composed of polymers of ethylene. PE can be clear or translucent depending on density. It is a tough, waxy solid, that is unaffected by water and is inert to a large range of chemicals. PE is marketed in three general classifications: low-, medium-, and high-density as follows:

Cellular polyethylene having closed, thin-walled cells filled with either air or other gas.

polyethylene, high-density (HDPE)

A hydrocarbon polymer that has linear chains allowing for dense packing resulting in a density between 0.94 and 0.96 or more. High-density polyethylene is economical, can be processed easily by most methods, has good moisture barrier properties, and good chemical resistance. It has a comparatively low melting point, is translucent in most forms, is relatively soft, has high elongation, and poor gas barrier properties. It is used for most household product bottles, many plastic bags, and for injection-molded dairy crates and beverage carriers, among other applications.

polyethylene, high-molecular-weight high-density

A polyethylene family generally defined as linear copolymer or homopolymer resins with average molecular weights in the range of 200,000 to 500,000. Melt flow index according to ASTM D 1238, Condition F is another way of defining them, since melt index is inversely proportional to molecular weight. Their high load melt index is in the range of 15 grams per 10 minutes. Most HMW polymer grades are copolymers in the density range of 0.944 to 0.954 grams per cubic centimetre. Grocery sacks, can liners and multiwall liners are major markets. Specific film end-use applications include meat, cheese, and poultry packaging, stretch film, bag-in-box, shrink film, frozen food packaging and medical packaging.

polyethylene, linear

Linear polyethylene encompasses high-density (HDPE), high- molecular-weight high-density (HMW-HDPE) and ultrahigh- molecular-weight (UHMW-PE) and is polymerized in reactors maintained at pressures far lower than those required in reactors used for making branched low density PE.

polyethylene, linear-low-density (LLDPE)

LDPE and LLDPE are branched hydrocarbon polymers differing from HDPE in that they have significant side branching that prevents dense packing of the molecules. In making LDPE, polymer density is varied by means of changes in reactor pressure and heat. LLDPE is a PE copolymer typically with made with octene or hexene components and has many, but very short, side branches. LLDPE density varies with the quantity of comonomer used with ethylene. The comonomer forms short-chain branches along the ethylene backbone, and since the branches create separations between the polymer backbones, the greater the quantity of comonomer, the lower the density of the polymer.

polyethylene, low-density (LDPE)

Low-density polyethylene and linear-low-density polyethylene (LLDPE), and blends or copolymers with other modifiers are often regarded as one family with similar applications. LDPE and LLDPE are both branched hydrocarbon polymers differing from high-density polyethylene (HDPE) in that they have significant side branching that prevents dense packing of the molecules. LDPE side branches are relatively long, while LLDPE has many, but very short, side branches. LDPE is characterized by good clarity, high elongation, and a low melting point. Major applications include heat-sealable coatings and films, stretch- and shrink-wraps, and retail and industrial bags.

polyethylene, medium density (MDPE)

A polyethylene with a density range between 0.926 and 0.941 having properties intermediate between HDPE and LDPE. See polyethylene.

poly(ethylene naphthalate) (PEN)

Poly(ethylene naphthalate) is produced from the monomer 2,6 naphthalate or naphthalene dicarboxylate (NDC). PEN has thermal properties making it suitable for hot-filling, is an excellent ultraviolet light barrier, and possesses excellent gas- barrier properties. PEN alone is costly. However, small amounts either copolymerized or alloyed with PET improve PET’s performance significantly.

poly(ethylene terephthalate) (PET)

A saturated, thermoplastic polyester resin made by condensing ethylene glycol and terephthalic acid. PET can readily exist in either an amorphous or highly crystalline state. PET has the highest tensile strength, stiffness, and use temperature of the commodity packaging polymers. It has good clarity and is a good all-around barrier. It is used in beverage bottles, meat packaging, boil-in-bag applications, and many other toiletry, cosmetic, household and pharmaceutical products. Dual-ovenable trays are made from amorphous PET sheet, which is crystallized for high-temperature service and can be used in either a microwave or convection oven. Microwavable paperboard food trays are often coated with PET. In general, PET films are used where high strength or high use temperatures are required. See also poly(ethylene terephthalate), crystallized and also polyester.

poly(ethylene terephthalate), crystallized (CPET)

Poly(ethylene terephthalate) to which nucleating agent has been added to encourage the development of crystallinity in extruded or molded products. The percentage of crystalline material is typically between 15 and 35. Barrier, modulus and strength increase with crystalline content.

polyethylene, ultra low-density

Essentially synonymous with very low density and referring to the category of linear polyethylenes with densities below 0.915 gram per cubic centimetre (g/cc). Current technology provides a lower density limit between 0.880 and 0.890 g/cc.


The polymerization product of isobutylene. It varies in consistency from a viscous liquid to a rubber-like solid. Used to improve impact in other plastics and as tackifying resins in adhesives.

polylactic acid (PLA)

A biodegradable polymer made from renewable resources (primarily corn-derived dextrose. Only recently made available in commercial quantities, PLA has potential applications for candy wraps, shrink films, heat sealant and thermoformed parts.


A large molecule composed of repeating units usually based on carbon. In some contexts polymer is synonymous with plastic.

polymer, amino

Polymers based on resins made by the condensation of amines with aldehydes such as urea and melamine.

polymer, amorphous

Describes a polymer that has an essentially random arrangement of the polymer chains. At melt conditions, all thermo- plastic polymers are amorphous. See also polymer, crystalline.

polymer, branched

A polymer that has side chains branching away from the main backbone chain. Depending on the nature of the polymerization, the side chains might be long or short. A branched polymer will have significantly different properties compared to a linear polymer of the same general chemistry. For example, low-density polyethylene (branched) is substantially different in its properties than high-density polyethylene (linear).

polymer, crystalline

Plastics with high molecular regularity are considered to be crystalline in nature. These typically more dense polymers include polyamides, poly(ethylene terephthalate), and high density polyethylene. Crystalline polymers are never wholly crystalline but contain some amorphous material and many crystallites. Many properties of a polymer are related to the degree of crystallinity. See also polymer, amorphous.

polymer, graft

A copolymer in which polymeric sides chains have been attached to the main chain of a polymer of different chemical structure.

polymer structure

The relative positions, arrangements in space, freedom of motion of atoms in a polymer molecule, and the orientation of chains. Polymer structure has a major bearing on the polymer’s final observed properties.

polymer terminology

Proper chemical names of many polymers are long, awkward to pronounce, and sometimes difficult to spell. Traditionally, in the workplace, this problem is circumvented by using trade names and/or abbreviations. However, this has introduced a different problem: a host of terminologies and abbreviations have been adopted without any specific standard as to how an abbreviation should be made, resulting in a number of different abbreviations for the same material. This text follows the recommendations of the American Society for Testing and Materials, Standard Terminology for Abbreviations Relating to Plastics, Designation: D 1600.


A chemical reaction in which the molecules of a monomer are linked together to form large molecules whose molecular weight is a multiple of that of the original substance. When two or more monomers are involved, the process is called copolymerization or heteropolymerization. See also polymer.

polymerization, addition

A chemical reaction in which unsaturated monomer molecules join to form a polymer in which the molecular formula of the repeating unit is identical (except for the double bond) with that of the monomer. The molecular weight of the polymer so formed is thus the total of the molecular weights of all of the combined monomer units. Polyethylene, polypropylene, and other polymers based on hydrocarbon chains are addition polymers. See also polymerization, condensation.

polymerization, condensation

A polymerization reaction in which water or some other simple molecule is eliminated from the monomer molecules when
they combine to form the polymer. Poly(ethylene terephthalate) and polyamides are the commonest packaging condensation polymers. See also polymerization, addition.

polymerization, degree of

The number of structural units or mers in the “average” polymer molecule in a particular sample. For most plastics the degree of polymerization (DP) must reach several thousand if worthwhile physical properties are to be had.

polymethylpentene (PMP)

A hydrocarbon polymer polymerized from methyl pentene. Unusual PMP properties are its low density (0.83) and its high (for a hydrocarbon) 160oC (320oF) service temperature. It has been used for such high-temperature packaging applications as cook-in-bag products and autoclavable medical supply packages. PMP’s high cost limits its use for most packaging applications. Most commonly known as TPX, its ICI trade name.


A polymer prepared by the polymerization of an olefin(s) as the sole monomer(s). See olefin.

polypropylene (PP)

A hydrocarbon polymer polymerized from propylene gas. Films are mostly oriented (OPP) or biaxially oriented (BOPP). In this form they are used for high-clarity wrapping stock, and when printed, are the predominant film for snack food packaging. OPP film has excellent clarity, low elongation, good moisture-barrier properties, and good low-temperature performance. Gas barrier and heat-sealability are provided by other added material layers. Polypropylene has a higher softening point than PE and is used to make bottles where elevated temperature will be a factor such as in hot-filling. Unoriented extrusion blow-molded and injection-molded PP does not have good low-temperature performance. PP is the polymer of choice for closures and dairy tubs.

polypropylene, biaxially oriented (BOPP)

A polypropylene film that has been oriented in two axis, normally in the machine and cross directions.

polypropylene, isotactic

Polypropylene in which each mer unit has the pendant -CH3 group on the same side of the chain backbone. Commercial PPs are about 90% isotactic, conferring high crystallinity and softening range. In contrast, atactic PP where the mer units are randomly arranged, is rubbery and weak. Most rigid polypropylene used in packaging films and moldings is isotactic. Atactic polypropylene finds some application in adhesives.

polypropylene, oriented

A polypropylene that has been oriented (OPP). Most polypropylene is biaxially oriented and would be more correctly referred to as BOPP.

polystyrene (PS)

A hard, brittle (unless modified), and exceptionally clear polymer, PS has good resistance to water, alkaline chemicals, acids, and detergents. However, elevated temperature or tensile stress may diminish chemical resistance. It is attacked by aliphatic and aromatic hydrocarbons and their derivatives. PS forms a good base sheet for thermoforming into portion cups, point-of-purchase displays, merchandising units, and internal. It is injection-molded into a variety of boxes and shapes used for cosmetics, jewelry, compact discs, hardware, and other items. PS can be readily expanded with blowing agents to make cellular plastics of varying densities useful for protective and shock-absorbing applications.

polystyrene, crystal

The term “crystal” when used to describe polystyrene refers to the appearance rather than crystalline structure of the polymer itself.

polystyrene, expanded (EPS)

Polystyrene and polystyrene copolymers supplied as a compound with blowing agents, and which can be processed into low density (0.7 to 10.0 pounds per cubic foot) expanded (foamed) articles. A major end-uses is for protective packaging.

polystyrene, high-impact (HIPS)

Impact polystyrene is a thermoplastic copolymer produced from styrene monomer and an elastomer. The modified polystyrene is not as brittle as the unmodified crystal polystyrene grades. It is formed into containers for food, fruit juice, and dairy products. Relative advantages for HIPS are ease of processing, good dimensional stability, high rigidity, and good low-temperature impact strength. Relative disadvantages of the material are poor barrier properties, poor grease resistance, and poor high-temperature resistance.

polystyrene, medium-impact (MIPS)

A polystyrene that has been modified, usually by copolymerization, to improve its resistance to cracking or impact. See also polystyrene, high-impact.

polytetrafluoroethylene (PTFE)Polytetrafluoroethylene is made by polymerizing tetrafluoroethylene. Inert to virtually all chemicals, PTFE has a crystalline melting point of 327oC, though it does not truly liquefy. Its inability to form a true melt requires special extrusion, molding, and calendering processes in which the PTFE powder is pressed, then sintered with heat. PTFE has exceptionally low coefficient of friction and resists adhesion to almost any material unless strenuously pretreated. Its nonstick character and high temperature performance makes it useful in machine applications requiring low coefficient of friction and/or high temperature tolerance. Marketed by Du Pont Co., Wilmington, Delaware, under the trade name Teflon.

polyurethane (PUR)

A polymeric material made by the reaction of any of a group of isocyanates with any of a group of multifunctional glycols. Depending on the participating monomers, urethanes can be made that have a wide range of properties (for example, thermoplastic, thermoset, rigid, elastic, cellular, and so on). See also, foam, polyurethane.

poly(vinyl acetate) (PVAC)

Plastics based on resins made by the polymerization of vinyl acetate or copolymerization of vinyl acetate with other unsaturated compounds, with vinyl acetate being the predominant component. Poly(vinyl acetate) is primarily used for the manufacture of water-based white emulsion adhesives. The abbreviation PVA is frequently used instead of PVAC. See polymer terminology.

poly(vinyl alcohol) (PVAL)

A water-soluble thermoplastic prepared by partial or complete hydrolysis of poly(vinyl acetate) with methanol or water. Its principal uses are in packaging films, adhesives, coatings, and emulsifying agents. Poly(vinyl alcohol) packaging films are impervious to oils, fats, and waxes, have very low oxygen transmission rates, and most often are used with other thermoplastics as a barrier coating or layer. The water solubility of the films can be regulated to some degree, but in most packaging applications, PVAL coatings or layers must be protected from water. PVAL is also abbreviated PVOH. See polymer terminology.

poly(vinyl chloride) (PVC)

Plastics based on resins made by polymerization of vinyl chloride or copolymerization of vinyl chloride with other unsaturated compounds, with vinyl chloride being the predominant component. Pure poly(vinyl chloride) is a difficult to process hard brittle material. For most packaging applications it requires the addition of a plasticizer or to be copolymerized with vinyl acetate. PVC in sheet form is the main material used for thermoformed display package blisters. It is also thermoformed into portion packaging and point-of- purchase displays. PVC films have good clarity and can be made into cling-type films and tamper-evident neck bands. Some plastic bottles requiring good clarity or resistance to hydrocarbon solvents are made of PVC.

poly(vinylidene chloride) (PVDC)

Plastics based on resins made by the polymerization of vinylidene chloride or copolymerization of vinylidene chloride with not more than an equal weight of other unsaturated monomers. The pure homopolymer is difficult to process and most packaging applications use a poly(vinyl chloride) copolymer. PVDC has excellent overall barrier properties and is used primarily in film form or as a coating to improve the barrier qualities of PET, OPP, PA, and other films. PVDC is commonly known by Dow’s trade name Saran. Films are transparent and have excellent cling.

poor trapping

The condition in wet printing in letterpress, flexography, and lithography when less ink transfers to previously printed ink than to unprinted paper. Also called undertrapping.


The presence of pores or minute openings in a material. A material characteristic that allows free passage of air or liquid. One measurement is the rate of air movement through a test specimen. The degree of porosity in a paperboard will affect ink and adhesive take-up, the action of vacuum cups on automatic machines, and the production of skin packaging.

portion pack

Any one of many disposable container types that have been designed to hold one portion of product for individual use. Most commonly found in foodservice usage, for example, jam, mustard, cream, sugar, and other condiments. Also called

a single-service package, a unit-dose package.


A photographic image on paper or film, that exactly corresponds to the original subject in all details. The opposite of a photographic negative.

post-consumer material

Any material generated by consumer, business, or institutional sources, which has served its intended end use and has been separated from municipal solid waste for the purpose of recycling. See PCR.

post-consumer recyclate (PCR)

Recyclable material whose origin is in consumer waste as opposed to in-plant reprocessing, industrial waste, or commercial waste.

post cure

The continuation of a curing process in an ultraviolet- or heat-curable material after the light has been shut off or the heat removed.


The conversion of a continuous-tone data into a series of visible tonal steps or bands.

pot life

Some adhesives or coatings may be composed of two reactive components that are blended immediately before use. The chemical reaction, usually polymerization, will eventually convert the mixture into a set solid. Pot life refers to the length of time during which the material can still be worked and applied to the substrate.


A small flat bag or envelope. Pouches can be made from tubular blown film stock in which instance the two open ends are sealed. A typical pouch made on a vertical form-fill-seal machine is made from a single web and has a seal across each and a longitudinal seal down the center of one long side. A typical pouch made on a horizontal form-fill-seal machine is made from a single web and has seals on three edges. Four side seal pouches are usually made from two webs and have seals along all four edges.

pouch machine

A machine for producing pouches from flexible packaging materials. In most instances, pouching equipment not only forms the pouch, but also fills and seals it. If so, it is more properly referred to as a form, fill, seal (FFS) machine. See form-fill-seal machine.

pouch, pillow

A bag or pouch sealed at both ends and not having a flat bottom so that it has the appearance of a pillow.

pouch, retortable

A flexible package able to withstand the rigorous temperature and pressure conditions of a commercial retort. Retortable pouches, or retort pouches, are constructed of a laminate composed of polyester, foil, and a polyolefin heat-seal medium. The military, a major consumer of retorted foods, refers to them as meal, ready to eat or MRE.

pouch, stand-up

A flexible pouch design where the bottom portion has been gusseted in such a way that it produces a wide enough base to provide support so the pouch is able to be stood up for display or use.

pouch, four-side-seal

A pouch with seals along all four edges. Four-side-seal pouches can be made from a single stock or the front and back can be different stocks. The pouches are most commonly made on multi-lane pouch-forming machines where 16 or more pouches can be placed across the width of the web.

preprint, preprinting

Any printing that is done prior to some other process or treatment. For example, a plastic film could be preprinted and subsequently sent to be metallized.


Any process that protects products such as food or pharmaceuticals from degradation by chemical action, the activity of microorganisms, the continuation of natural biological processes, or other effects that would reduce product quality.

press-through package

Most typically a series of thermoformed pockets in a plastic sheet into which pharmaceutical tablets are placed. These are then sealed into their respective pockets with an aluminum foil-based backing sheet. Individual tablets are pressed through the aluminum foil, and the torn foil provides tamper evidence.

press sheet

A single sheet of paper or paperboard of the size that will fit a specific sheet-fed printing press.

press, central impression cylinder

A type of flexographic printing press in which the web being printed is in continuous contact with a single large diameter impression cylinder. The color stations are moved into the central impression cylinder for printing and are arranged around its circumference. Central impression presses maintain better register with highly extensible materials such as low- density polyethylene than in-line presses.

press, combination

A press with print stations using two different printing methods. Most commonly, the press would have gravure printing stations with additional flexographic or lithographic print stations. This allows for the application of the best features of two printing methods. For example, a package may be printed primarily by flexography (for economy), excepting for a vignette that is better printed by gravure. In another instance, the basic art on a high volume package might be printed by gravure, but a selected area that changes frequently might be printed by lithography or flexography. Also dual-mode or hybrid press.

press, flexographic

A printing press that uses printing plates made from rubber or synthetic elastomeric materials. Flexographic presses may have their individual printing stations arranged in a horizontal line (See press, in-line), grouped around a central impression cylinder (See press, central impression), or stacked in a vertical arrangement (See press, stack). Most flexographic presses, excepting those used to print corrugated board, are web-fed. See printing, flexographic.

pouch, three-side-seal

A pouch that is formed by folding the web material into a u-shape and the sealing the three open sides. The pouch may be made with a gusseted bottom. Three-side-seal pouches are typically produced on a horizontal form-fill-seal machine.

pouch, zipper

A flexible plastic pouch with a molded-in-place sealing device wherein a projecting rib or fin is inserted into a mating channel to effect a closure. A zipper seal can be repeatedly opened and closed.


See polypropylene.


An insoluble substance that forms in a solution.


A check of a computer graphic file required to ensure that all elements required to go to print are present and correct.


To form or produce part or all of a pouch or package before subsequent operations as for example filling.


A polymer of low molecular weight to be further polymerized to its final form.


Those activities necessary to the preparation of art for printing. For example, separation of the image into component colors, imposing the screen, production of photonegative or digital records for each color, proofing of images, manufacture of printing plates, and the make-ready of the press for printing.

prepress, electronic

The computer-assisted design of graphic and structural elements from concept to films or electronic records ready for platemaking.

press, gravure

A printing press that uses an engraved metal cylinder as an image carrier. Gravure presses are almost always web fed. See printing, gravure.

press, in-line

(a) A press coupled to another operation, such as slotting, die cutting, folding, etc. (b) A multi-station printing press in which the print stations are mounted horizontally in a line.

press, molding

A platen press in which matrices or rubber plates are formed.

press, offset

A printing machine that transfers or offsets impressions from the inked printing plate to an intermediate rubber covered cylinder (the blanket cylinder), and then to paper or other substrate. All lithographic presses are offset. Letterpresses are offset when they are used to print round forms (also know as dry offset).

press, perfecting

A printing press that prints both sides of the paper in one pass. A typical packaging arrangement is to have one or two stations capable of printing the back side of a sheet or web.

press, platen

  1. a) A press in which in which one flat surface is pressed against another flat surface. At one time, all printing presses were platen presses with printing plates attached to one surface and the paper resting on the other. Die-cutting presses are often platen presses. b) A heated press that forces the matrix material into the metal engraving or the rubber into the cured matrix during the production of rubber flexographic printing plates.

press, proofing

A press used to print progressive proofs.

press, sheet-fed

A press that prints or treats predetermined sizes of flat sheet- stock as compared to web-fed presses that print or treat continuous roll-stock.

press, stack

A flexographic press where the printing stations are placed one above the other, each with its own impression cylinder.

press, web

A press that prints, laminates, or otherwise processes roll-, or web-fed, paper, films, or foils.


The force per unit area that is acting on a real or imaginary surface. It is expressed in pounds force per square inch or in pascals.

primary colors, additive

Red, green, and blue (RGB) are the primary additive colors of light and the colors perceived by the human eye. See also primary colors, subtractive.

primary colors, subtractive

Cyan, magenta, yellow, and black (CMYK) are the primary ink colors used for full-color process printing. See also primary colors, additive.

primary package

The first wrap or containment of a product.


Application of a base coating to a material to make its surface more receptive to inks, coatings, adhesives, films, laminates, or other finishes.


A coating applied to a substrate for the purpose of providing a better adhesive bond to a subsequently applied coating, adhesive, or ink.


(a) (noun) A design resulting from printing. (b) One color or pass in the formation of a design requiring several passes for completion, as in lithography, letterpress, gravure, or flexographic printing. (c) (verb) To transfer written matter or design to an object, usually by means of a stamp, die, or printing press, with ink as the medium. To imprint.


That ability of a material to yield printed matter of good quality. Printability is judged by the print quality and uniformity of ink transfer, rate of ink wetting and drying, ink receptivity, compressibility, smoothness, opacity, color, resistance to picking, and similar factors. Printability is different from runnability, which refers to the efficiency with which the substrate may be printed and handled in the press.

print contrast signal (PCS)

The measure of the contrast between bars and spaces in a machine-readable bar code. Codes with insufficient contrast will not scan.

printer, nonimpact

Any electronic device such as a copier, and laser or ink-jet printer that creates images on a surface without contacting it.


The production of multiple images on a substrate at high speed.

printing, aniline

An early name for flexographic printing at a time when the printing inks were based on aniline dyes.

printing deck

See deck, printing.

printing, dry-offset

A printing process involving flexible plates with raised images similar to flexographic plates. Unlike flexography that uses a fluid ink metered by an anilox roll, dry offset meters a heavy paste ink using an ink train. The ink is transferred or offset from the printing plate to a resilient blanket cylinder, and then to the material to be printed. The main application is for printing round containers such as cans, tubes, or tubs. The entire image is assembled on the blanket, and transferred to the object in one pass. The process is also referred to as offset letterpress.

printing, face

(a) Printing on the outer surface of a transparent film in contrast to printing on the back of film. The opposite of reverse printed. (b) Printing on the face of a bag or label.

printing, flexographic

A method of printing
using flexible rubber
or photopolymer
printing plates in
which the image to be
printed stands out in
relief. Fluid ink
metered by an
engraved roll or
anilox roll is applied
to the raised portions
of the printing plate and then transferred to the substrate. Flexographic printing is primarily used to print sheets of preformed corrugated board and for printing roll-fed film and paper. Formerly called aniline printing.

printing, hot-stamp

A decorating method that uses heat to melt and transfer a thermoplastic ink or substance from a carrier film onto the object to be printed. A heated die with the desired pattern engraved into it is pressed against the carrier film to effect a transfer of a decorative pattern. A major application is to transfer aluminum metallizing. The resulting pattern will have a high metallic luster. Also called hot foil stamping, hot-leaf stamping and roll-leaf stamping.

printing, ink-jet

A computerized method of forming an image by controlling the flow of a stream of ink droplets or by generating drops as demanded by the computerized image.

printing, intaglio

(a) A printing process method based on the gravure process either from a cylinder or a flat plate. (b) An engraved or etched design that is below the surface as cells in an anilox roll or gravure cylinder.

printing, laser

A method in which an electrostatic image is produced with a laser beam on a semiconductor drum and developed and printed with a toner. See also laser marking.

printing, letterpress

A printing process using relief plates similar to flexography except with rigid raised images. Letterpress inks are viscous pastes metered by roller trains.

printing, noncontact

Any of several methods such as laser marking or ink-jet printing that produce a mark on the substrate without making actual physical contact between a printing plate and the substrate.

printing, offset

An indirect printing process in which the inked image created by the image-producing plate (lithographic, gravure, or flexographic) is transferred to an intermediate roll (the blanket roll) and subsequently applied to the substrate. In packaging, lithographic printing is always offset. See also blanket roll.

printing, offset letterpress

A printing process involving flexible plates with raised images similar to flexographic plates. Unlike flexography that uses a fluid ink metered by an anilox roll, dry offset meters a heavy paste ink using an ink train. The ink is transferred or offset from the printing plate to a resilient blanket cylinder, and then to the material to be printed. The main application is for printing round containers such as cans, tubes, or tubs. The entire image is assembled on the blanket, and transferred to the object in one pass. The process is also referred to as dry offset.

printing, gravure

A printing method that uses cells etched or engraved into the surface of a metal cylinder to meter and correctly pattern a thin, quick- drying ink. Gravure printing presses used in packaging are predominantly roll-fed. Also called rotogravure or roto.

printing, heat-transfer

A decorating method that uses heat to transfer a preprinted thermoplastic ink design from a carrier film onto the substrate

printing, off-set lithography

cylinder. Ink is metered to the inside of the cylinder, and wiped through the screen openings as the screen is rotated against the substrate. Rotary screen printing is typically is found on narrow-web label printing presses, often in combination with flexographic or other print method stations. See printing, screen.

printing, rotogravure

See printing, gravure.

printing, screen

A decorating method that uses a metal or plastic mesh screen that has been masked or blocked off in the nonprinting areas. The screen is placed over the object to be printed. Ink wiped across the screen will pass only through the remaining porous areas to create an image. Screen printing is used primarily to decorate glass and plastic bottles, and to print large POP displays. Since silk is no longer used as a screen material, the term silk screen is not correct.

print show-through

See show-through.

printing, silk-screen

Screen printing using silk as the screen material. Although the term is still commonly used, it is technically incorrect since most modern screens are made from polymer filaments or metal wire. See printing, screen.

printing, ultraviolet

A printing method that
is based on the mutual
repellency of oil and
water. A lithographic
printing plate is
chemically altered to
produce oil-attracting
and water-attracting
areas. When an oil-
based ink is applied, it
adheres only to the oil-
receptive area. Metal
printing plates cannot
follow small substrate
irregularities so the wet ink image is transferred or offset onto a rubber blanket cylinder and then to the substrate, hence the term offset lithography. Offset lithography is mostly used to print paper and paperboard stocks for labels and cartons. Most packaging lithographic presses are sheet fed, although there are some roll-fed presses. Oil-based inks do not adhere as well to plastic surfaces, so the process has limited application in this area. Also known as offset or litho.

printing, pattern

Usually describes the application of adhesives to a substrate in a predetermined pattern by methods similar to printing.

printing plate

The plate, cylinder or material that develops the inked image in a printing process. A printing process is normally named after the nature of the printing plate.

printing, process

A printing method that reproduces a full-color image, normally using the four process colors, cyan, yellow, magenta, and a key color.

printing, random

Arrangement of the print on overwrapping material to eliminate the need for registration on the wrapping machine.

printing, relief

A printing method that uses a plate on which the image is formed by those portions that are raised above (stand out in relief to) the plate surface. Flexography, letterpress, and letterset are relief printing processes.

printing, reverse

Printing on the reverse side of transparent film so that the printing will be on the inside of the package and observable through the film. Reverse-printed films usually are laminated so that the printing is locked between two plies. Reverse printing takes advantage of the glossy exterior surface of the printed film.

printing, web

(a) The process of continuous printing of packaging material being unwound from rolls (b) Process of printing packaging material as it is transferred from roll to roll, i.e., unwound and rewound.


The degree to which a sheet’s transparency and ink penetration permits an image printed on it to be seen from the reverse side. Also print show-through.


The ease with which a material can be converted to high- quality, useful products with standard techniques and equipment. For example, polyethylene, which is readily processed at low temperatures with no pretreatments, would be considered more processable than polyamide, which requires a much higher melting temperature and might need to be dried prior to processing.

processing aid

A substance added to a material to improve its behavior during processing. Plastic processing aids may include heat stabilizers, lubricants, plasticizers, and other resins. In papermaking, processing aids may include wetting agents, anti-foaming agents, and other additives whose purpose is to stabilize and improve the production rate of a papermaking machine.

processing window

The range of a particular condition, for example, temperature when making a heat seal, within which the desired effect can be obtained. When the desired effect can be obtained over a wide range of conditions, the process is said to have a broad processing window. A narrow processing window would have a very small range of conditions at which the desired effect can be obtained. Generally, processes with wider windows are more desirable.

product stewardship

A management concept that accepts responsibility for a product over its full life cycle including the proper disposal of byproducts and packaging, and the used product itself at the end of its life.


The output of a packaging machine or line expressed as a proportion of some given unit cost.


The printing of special test sheets consisting of a large selection of color rectangles. The printed test sheet is passed through a reader that determines how the press will print each color, and uses this information to correct digital prepress proofs so that they will more closely imitate the final printed product.


A device for measuring roughness of surfaces. This device determines the root-mean-square surface roughness in micro- inches (millionths of an inch).


(a) Most commonly a chemical added to inks, adhesives and coatings to accelerate their rate of cure. (b) Any other additive that improves some property or activity as for example an adhesion promoter.

proof, proof print

A analog or digital print or trial impression made to verify the correctness of graphic art as it progresses through various stage between initial design and the printing of the final

product. Proofs to verify position and copy may be made black and white. More advanced proofs simulating the final copy will be in full color.

proof, color

A prepress proof made to simulate the colors in the final product. The proof may be produced by analog or digital technology. Examples are Cromalin, Waterproof, AQ4 (Du Pont), Fuji, Matchprint (Eastman Kodak). See proof.

proof, digital color

An off-press system that allows a hard copy color proof to be produced directly from digital information without the need for intermediate photo negatives. Many commercial systems are available. These are based on technologies such as die sublimation, thin layer thermal transfer, thermal laser dry ink jet, and continuous flow ink jet. See, proof color.

proof, off-press

Proof made by analog or digital means in less time and at lower cost than press proofs. See proof.

proof, position

Proof for checking position, layout, and/or color breakout of image elements. Position proofs are often done in black and white.

proof, press

Printed section of substrate material made on a printing press to allow for approval or final corrections before the production printing run is made.

proofing, remote

A system of proofing graphic art by a customer wherein the customer has a connection to the designer’s computer and is able to call up the images on his own system for proofing.

proofs, progressive

Proofs made from the separate plates in color process work. Transparent proofs can be overlaid to show the sequence of printing and the result after each additional color has been applied. Progressive proofs provide for verification of correct color placement and alignment with other package features. They do not provide for a check on the exact color that will be printed. Color Keys are an example of progressive proofs. Often dubbed “progs.”


A set of procedures. Test protocols, for example, are the set of instructions that govern how a test is run.


See polystyrene.

pseudoisochromatic plate

The revised American Optical Company test selection based on the Schilling and Ishihara charts, which has been approved by the Inter-Society Color Council Subcommittee on Color Blindness Studies.


(a) To clean out an extruder barrel in preparation for extruding another material. (b) More generally the removal of any undesired material.


See poly (vinyl chloride).


See poly (vinylidene chloride).


An abbreviation for poly(vinyl alcohol). See poly(vinyl alcohol).


A depreciated abbreviation for poly(vinyl alcohol).

pyramid cell

One of the several designs of engraving used for anilox roll construction. It is characterized by a slight flattening at the top and a sharp “V” shape at the bottom.


The depolymerization of a polymer at 500 to 900oC in an oxygen-less environment. Depending on the polymer mixture, basic gases such as hydrocarbons, ammonia, and hydrogen chloride are produced, along with 25 to 40% synthetic crude oils and some solid residues.


The study of motivations, perceptions, and attitudes.


An instrument for measuring the humidity (water-vapor) content of air by means of two thermometers, one dry and one wet. Considered the most accurate of the instruments practical for industrial plant use for determining relative humidity.


Describes a microorganism that will tolerate and propagate at below ambient temperatures.

pull date

A date printed on the package of a perishable good that indicates the date on which it must be pulled from shelf and no longer offered for sale.

pull strip

Strip or tape, with one end projecting, which permits the opening of a package or container when pulled. See tear strip.

pull tab

An area or device that facilitates easy grasping and pulling of a feature such as a tear tab or a peelable adhesive construction.


The extracted mass of fiber, water, and other constituents to which a wood source is reduced by mechanical or chemical means in the process of papermaking. Pulping is the

quality package

A package that meets all design specifications and is manufactured in compliance to ISO 9001 or ISO 9002.

quality program

The documented plans for implementing the quality system.

quality system

The collective plans, activities, and events that are provided to ensure that a product, process, or service will satisfy given needs.

quality, relative

Degree of excellence of a product or service.


To cool rapidly for example by water immersion.

quick set

To dry or cure rapidly.

quiet zone

In bar coding, the area immediately surrounding the code that is kept free of any markings or features that might be read as part of the code. Quiet zones also make it easier for human observers to locate the code. As a general rule, the quiet zone should be at least ten times the width of the narrowest bar or space in a code.

quad cell

A truncated pyramid cell that creates a flat bottom of the cell as opposed to a sharp pointed bottom. The flat bottom assists in ink release and cleaning.


Conforming to requirements or specifications.

quality assurance

A system of activities whose purpose is to provide assurance and show evidence that the overall quality-control function is being accomplished. Often abbreviated QA.

quality audit

The monitoring of quality at any stage to provide information.

quality control (QC)

The activities that monitor and maintain product quality characteristics within specified limits. These activities include sampling of the product, measurement of critical quality characteristics, testing, continuous statistical analysis, presentation of the data, and decision making regarding acceptance, rework, or scrapping of a lot.

quality function deployment

A set of techniques for determining and communicating customer needs and translating them into product and service design specifications and manufacturing methods.

radiation cure

The curing of a coating, printing ink, adhesive or other material by the use of high energy radiation such as electron beam or gamma. In some applications the term also includes curing by ultra violet light. Radiation cured substances are typically 100% solids materials that solidify by a polymerization reaction initiated by the high-energy radiation. See radiation, electron beam; radiation, gamma; ultra violet curing.

radiation sterilization

The process of sterilizing the contents of sealed packages containing foods or medical materials by exposing them to controlled levels of high-energy radiation, usually either gamma from a cobalt-60 source or electrons from guns. The process provides total destruction of microorganisms, is safe, is performed at ambient temperatures, provides flavor advantages over some other methods of sterilization, and increases shelf of some foods. Radiation sterilization with gamma rays or electron beams cannot induce radioactivity in the treated material. See also irradiation and radiation, gamma.

radiation, electron-beam (EB)

Magnetically accelerated electrons focused by electric fields are used for cross-linking polyethylene to improve modulus and temperature resistance, and to cure coatings and adhesives, eliminating the need for photoinitiators. Treatment levels must be controlled since overexposure will cause degradation. Electron beams also can be used to sterilize materials or products similar to gamma irradiation.


Dial or indicator giving the result of any counting, weighing, measuring, or testing instrument. The data also may be produced in printed form, and the jargon then becomes “printout.”

real-time processing

The ability of a vision system to interpret an image in a short enough time to keep pace with most packaging and manufacturing operations.


A measuring unit used to market paper. Paper weight is sometimes expressed as pounds per ream (ream weight), with a ream being defined as 500 sheets (in a few instances, 480 sheets) of a particular size. Historically there have been many sheet sizes. The most common packaging ream is 500 sheets of paper measuring 24 x 36 inches (3,000 square feet). TAPPI T410 lists the various trade sheet sizes used in the ream measuring system. The equivalent measure in metric is grammage, the mass in grams of 1 square metre.


The heating of any precooked frozen food in its package in preparation for serving.


The fourth of the four Rs of environmentally responsible packaging. After reduce, reuse, and recycle aspects have been considered, is there some other value that could be recovered before consigning the used packaging material to a landfill? For example, plastics and papers have been incinerated to recover their fuel value. Both glass and mixed plastics have been used to extend road-building asphalts.


Capable of being removed or sorted from the solid-waste stream in an established program and returned to use in the form of raw materials or products.


Separated or removed from the solid-waste stream, processed, and returned to use in the form of a raw material or product.

recycled content

The percentage of a material that is composed of recycled material.

recycled material

Material that would otherwise be destined for disposal as solid waste and is reworked into marketable end products. This includes, but is not limited to post-consumer material, industrial scrap and overstock or obsolete inventories. It does not include those materials and by-products generated from and commonly reused within an original manufacturing process.

Electromagnetic energy emitted from radioactive materials such as cobalt 60) as they decay. Gamma radiations are similar to, but of much shorter wavelength (typically 0.03 nm) and much higher energy than X-rays. They are highly penetrating, capable of passing through several centimetres of lead. Gamma radiation is used to sterilize medical supplies; an advantage being that the product can be sterilized when already sealed in its packaging. Various food products also can be gamma irradiated to improve their keeping qualities. Gamma irradiation also is used to initiate cross-linking and other changes in polymeric materials. See radiation sterilization.

radio frequency (RF)

An electromagnetic wave. RF energy can be used to weld selected plastics. See heating, dielectric.


(a) The difference between the highest and the lowest in a set of numbers. (b) The time available between application of an adhesive to a substrate and the closing of the bond to the second substrate in time for adequate bond formation to take place.

rate of set

The time required for an adhesive to produce a fiber-tearing bond under a specific set of conditions.

recycling rate

The percentage by weight of packaging distributed for sale in a specified region that is brought back and reprocessed into marketed end products, which otherwise would be disposed of as solid waste. Some jurisdictions base environmental legislations on recycling rate data.


Solvents or other liquids used to reduce the body or viscosity of inks, coatings, or adhesives.


(a) Any device on which a material may be wound. Usually has flanged ends and is used for shipping or processing purposes. See roll. (b) Sometimes used in reference to the mill or jumbo roll.


Intended to be refilled for its original purpose one or more times.


The amount of light returned from an illuminated surface.

reflectance, average background

Expressed as a percentage; the simple arithmetic average of the background reflectance from at least five different points on a sheet.


Ability to bend light from a straight course. Materials differ in refractivity, which is defined as “refractive index.”

refractive index (sodium D)

The ratio of the velocity and light in a vacuum to its velocity in the material as measured by ASTM D 542.


In relation to desiccants, the driving off of absorbed water by means of heat or vacuum, thereby restoring the original capacity of the material to absorb water. Reactivation.


Exact alignment of one part or operation with another part or operation. Most often applied to printing to describe whether applied colors are in their exact correct position relative to one another. See also register, butt, register, kiss, register, print-to-print, register, print-to-cut; and register, hairline.

register mark

Crosses or other target marks used for positioning films and printing plates in order that printed colors are in perfect alignment with each other and the boundaries of the material printed. Register marks may also be used for maintaining exact positioning for activities such as locating embossing or the cutting of a substrate material at the correct position.

register, butt

Printing of two or more colors that meet exactly without any provision for color overlap. Also referred to as kiss register.

register, hairline

In printing, register of two plates within plus/minus one-half row of dots.

register, pin

The use of accurately positioned holes and pins on copy, film, plates, and presses to insure proper register or fit of colors.

register, print-to-cut

Alignment of the printed sheet with the die-cutting tool. See also register, print-to-print.

register, print-to-print

Alignment of each printed color with the preceding and printed colors. See also register, print-to-cut.

register, running

Control of a printing press that allows accurate positioning of the printing of each color station relative to all other printing and die-cutting stations in the direction of web travel. Also called circumferential register and longitudinal register.

register variation

Amount or degree of tolerance allowed for the position of respective printed colors to vary or the actual measured amount. The amount by which respective colors or die-cuts are out of register.


(a) Any exact alignment between materials, graphic designs, or processes. When a design is printed and/or die-cut in parts, as in multiple colors or printing and die-cutting in sequence, the parts must match precisely, “in register.” For example; the alignment of a printing plate with the stock, the alignment of one printed image with another (print to print register), the alignment of printing and die-cutting (print to cut register). Otherwise, they are out of register.


Thermoplastic waste material such as sprues, runners,
parison trim material, sheet trimmings, and rejected parts from plastic manufacturing, that have been reclaimed by shredding or granulating. Regrind is usually mixed with virgin compound at a predetermined percentage for remolding. Current usage differentiates between regrind (in-plant recovery) and recycle (recovery after the material has served its purpose).

regulatory product

Products that are designated as hazardous articles by the U.S. Department of Transportation (DOT) and may be shipped only when their packaging, packing, and labeling comply with the regulations promulgated by the agency.



The activation of a dried adhesive film with water or suitable solvent.


The force or pressure required to remove a pressure-sensitive adhesive from a substrate. Depending on the application, either high or low removability may be required. A price tag or container label would require high removability force, while a peelable package would require a lower removability force.


Producing or the finished production of a design drawing, painting, etc. by hand using any of various artist’s tools, i.e., pencils, pens, knives, brushes, air brushes, etc.

repeat, repeat length

Printing length of a plate cylinder, determined by one revolution of the plate cylinder gear.

reroll stock

Aluminum billets intended to be rolled into foil.


The ability of a material to recover its original shape and dimension after being distorted.


(a) Any of a class of solid or semisolid organic products of natural or synthetic origin, generally of high molecular weight, and with no definite melting point. Most resins are polymers. (b) A portion of the ink vehicle that forms the binder. (c) Often used to describe polymer pellets prior to processing.


The number of pixels present in a digitized representation of an imaged scene. The higher the number, the greater the resolving power of the imaging system. Higher resolution yields finer detail in a given field of view.


A chemical added to adhesives, coatings, and printing inks for the purpose of slowing down drying rates, curing rates, or some other specific chemical activity.


A large pressure-cooking chamber used for thermal processing of packaged food products in hermetically sealed containers where temperatures above 100oC (212oF) are required for sterilizing purposes. Sterilization may be accomplished in a steam atmosphere only or using water heated by high temperature steam.


(a) (noun) A material or part that has been rejected for its intended purpose because of defects or imperfections.(b) The act of removing a defective part.

relative humidity (RH)

The ratio of actual amount of water that the air is holding to the maximum amount of water that air can retain without precipitation at a given temperature and pressure. It is also the ratio of the partial pressure of water vapor present to the vapor pressure of water at the prevailing temperature. Relative humidity (RH) is expressed as a percentage of saturation. High RH, which occurs in summer in many manufacturing-plant atmospheres and aboard cargo ships, can cause condensation of water on cool surfaces. See humidity, absolute and humidity, ambient.

relative humidity, equilibrium (ERH)

The humidity at which the moisture content of a material and the surrounding relative humidity are in equilibrium. The material will neither absorb moisture nor lose moisture to the air.


(a) To break free or to overcome adhesion. (b) The force required to separate a pressure-sensitive label from its release liner or carrier.

release agent

A coating or film applied to a surface to prevent or reduce its adhesion to another material. Release agents applied to plastic films are often called anti-blocking agents. When applied to molds they may be called mold release, or parting agent. Release agents will vary depending on the nature of the materials involved. Waxes, silicone oils, and fluorocarbons are the most common. Also abhesive.

release coat

A coating material applied to a substrate for the purpose of reducing the adhesive bond made by the adhesive on a pressure-sensitive label to the carrier web. Most release coatings are based on silicone or fluoropolymer compounds. See release agent.

release coat transfer

The transfer of a release coating from the carrier web to the pressure-sensitive adhesive during release.

release liner

The carrier sheet or web to which a pressure-sensitive label is attached. Release coatings usually are applied to the face of the carrier material so that the label adhesive will form a minimal bond to the liner and be easy to remove. See also backing and carrier web.

release paper

A paper that has been coated with a release agent (an anti- adhesive most commonly silicone or fluoropolymer based) to prevent the formation of a permanent adhesive bond. Release papers are used to hold pressure-sensitive labels and to back certain adhesive tapes. See release agent.

retort pouch

See pouch, retortable.


Capable of withstanding the temperature and pressure conditions of a closed retort at standard retorting conditions.


A package or component intended to be returned one or more times in an available program. The intent of returning the container may be for purposes of refilling, adapting to other uses, or to facilitate a central collection system for recycling.


Rework refers to components or packages produced that are of unacceptable quality but are acceptable for reprocessing. Furthermore, the product is reclaimable and some input items are reusable. If the product cannot be restored to an acceptable quality, it becomes wastage.


A material that has been taped to a shaft and wound back into the original roll form after it has gone through a process such as printing, laminating, or slitting.

reverse-roll coating

A method of applying a coating where an initially metered coating is applied to the substrate from a roll rotating in a direction opposite to that of the web travel.


Red, green, blue, the additive primary colors, and the colors of light perceived by the human eye.


The fluid flow (viscosity) characteristics of a given material.

right reading

The visual orientation of copy from left to right in a readable position.

rigid packaging

A package that has a specific size and volume, and is capable of supporting itself. Metal cans and glass bottles are the most common examples of rigid packages. Rigid packages are readily conveyed, can tolerate a certain amount of physical forces such as pressure or vacuum, and their reasonably consistent volume allows them to be used as the measuring device in certain filling operations. Compare to flexible and semirigid packaging.


The ability of a material or shape to resist deformation under load. Rigidity is a function of the material’s modulus of elasticity and of the object’s shape.


A generic term for a circular or cylindrical form. (a) The form of a flexible web wound around a central core (b) A cylindrical machine part usually able to rotate on its axis or shaft. It may be powered or free wheeling (idler).


A package or component intended to be used for its original purpose one or more times in an available program.


The second of the four Rs of environmentally responsible packaging. After taking all possible actions to achieve the first R (reduce), attention should be paid to whether the package or some component of the package can be used again. Refillable packaging and hand pumps that can be transferred to another bottle are examples.

reversed-out printing

Text or images formed by coloring the area around the letter or image and allowing the substrate color to show through rather than printing the letter or image shape itself. Reverse type for fine text should be avoided, since the ink gain in the printing process will tend to fill in the reverse-type letter.

reverse print, reverse printing

An image printed on the back of a clear material so that it will be read by looking through the material at the inked surface.

reverse reading

Describes an image that is the mirror or reverse image of the desired text or illustration. A direct-print printing plate will be reverse reading so that when the image is transferred to the substrate, an image that reads correctly will be formed. Where a blanket roll will be used (as in lithography) the image will be correct reading on the printing plate, reverse reading when transferred to the blanket roll, and correct reading when transferred to the substrate.


To wind again after a web material has been processed; for example, the rewinding of a roll of paper, film, or other flexible packaging material after printing, laminating or slitting.

rewind stand

On a web-fed machine, the station where the completed material is rewound back on a core.

roll, anvil

A hardened steel roll on which the bearers of a rotary die cutter ride and against which the cutting dies act.

roll, applicator

Any roll used to apply ink, adhesive, or other fluid material. Might also be described as a coating roll, fountain roll, and other variations.

roll, engraved

A roll used to apply adhesives, inks, coatings, and other fluid materials. The roll surface is patterned with cells engraved mechanically or by laser. The amount of fluid material carried is controlled by cell size, geometry, and density. See roll, anilox and printing, gravure.

roll, bowed-expander

Curved rubber-covered rollers designed to remove wrinkles or expand extensible films. Also called spreader rollers.

roll coating

A coating method where the coating material is metered by transfer between various rolls and the application is achieved by the final roll contacting the web an rotating in the same direction as the web travel.

roller rack

A storage rack having tiered load-supporting surfaces of roller. See flow rack.

roller, driven

Any powered carrying roller as compared to an unpowered idler roll.

roller, expander

Curved rubber-covered rollers designed to remove wrinkles or expand extensible films.

roller, guide

A roller capable of being skewed in order to control the lateral position of a moving web on-machine. Also called tilt guide.

roller, outboard

A cantilever-supported roller.

roll, feed

The rolls into which the blanks are initially fed. Also called pull roll.

roll, fountain

Roll that picks up the ink or coating material from the fountain and applies it to the transfer roll. In some design configurations, the transfer roll also acts as the fountain roll, particularly when a doctor-blade ink metering system is used.

roll, jumbo

A roll of web material with a larger than standard diameter. Usually refers to flexible material rolls as produced at the primary manufacturing point. Jumbo rolls are slit to widths according to the needs of the various converting plants using that material. Also mill roll and master roll.

roll, knurled

See roll, engraved. Also see roll, feed and roll, pull.

roll, master

A full width finished roll as it comes off a primary processing machine. Master rolls normally will be trimmed and slit to a customer’s specifications. Also mill roll and jumbo roll.

roll, mill

Roll of paper or plastic film as received by the converter from the mill. Also master roll or jumbo roll.

roll, Mount Hope

A bowed spreader roll, most commonly used after slitting a master roll, to spread the separate slit webs apart prior to be being rewound onto their respective cores. Named after Mount Hope Machinery, the originator of the design.

roll out

Color sample made with hand proofer to simulate press results. See drawdown.

roll, pick-up

A spreading device where the revolving roll for picking up the adhesive runs in a reservoir of liquid adhesive. Also fountain roll.

roll, pull

Full-width cylinders used to convey blanks through a press. These may be knurled or engraved in some manner to increase the coefficient of friction of the materials of construction as compared with smooth rolls of the same material. Also known as feed roll.

rolls, dancer

A group of rolls usually mounted on a movable frame, frequently found on web-fed converting machines. Different amounts of web material can be accommodated by varying the distance between the rolls. Dancer rolls smooth out material flow and provide a brief pause of web flow ahead of operations that are intermittent without actually stopping the main web flow. Dancer rolls serve as tension-sensing devices in extrusion coating, and as tension-maintaining devices in film winding.

roll, spreader

A roll used on film processing machines such as printers, laminators and slitters, and whose purpose is to smooth the film and keep it flat and taut across the machine direction. This is done by creating a dual spiral pattern on the roll surface that constantly tries to move the passing material to the outside edges of the roll.

roll, telescoped

A roll material defect in which one end is concave and the other convex. Usually caused by the sliding of inner layers of the rolled material.

roll, transfer

Roll rotating in contact with another roll or metered by a doctor blade, transferring variable amounts of ink in an inking system. May also serve a similar purpose with coatings and adhesives.

roll, untrimmed

Rolls of stock as wound at the end of the converting machine without being slit to remove rough, uneven edges, deckle edges, etc. Also, rolls of film, foil, etc., prior to trimming their edges.

roll, wipe

A roller, usually covered with neoprene, which is kept close to or in contact with the anilox roll for the purpose of metering excess ink from it.


A resinous substance having high tack properties obtained from the saps and extracts of pine and other trees. Pure rosin is brittle and friable, and is used mostly for sizing paper. Modified rosins are used primarily to increase the tack of printing inks, pressure-sensitive adhesives, and hot melt adhesives.

rotary machine

Any machine in which the main activity is performed with rotational rather than with reciprocating motions. Rotary machines are primarily continuous-motion machines while machines based on reciprocating movements are typically intermittent-motion machines. Rotary machines are capable of significantly higher speeds. See continuous motion and intermittent motion.


Abbreviation for recycled poly(ethylene terephthalate).

rub resistance

Ability of an ink film or other surface to withstand rubbing or scuffing without film deterioration. The Sutherland ink rub tester is an instrument commonly used to evaluate the rub resistance of inks.

rub resistance, wet

(a) Resistance of a printed surface to rub off when the ink has not completely dried. (b) Resistance of the surface of wet paper to abrasion.


An elastomeric material that is capable of recovering from large deformations quickly and forcibly. In its strictest sense the term should be used only in reference to materials made from the sap of a rubber tree. Synthetic materials having similar properties are elastomers. See rubber, natural.

rubber, natural

The coagulated latex sap from a rubber tree. Natural rubbers are used in cold seal and other adhesive formulations.

run-up period

Generally taken to represent the period of time after a changeover has been completed to get the actual run speed up to 80% of the achievable run speed.

run chart

A type of chart used to track one variable of a manufacturing process over time, typically associated with statistical process control techniques.

run in

The initial operation of a machine or line for a period of time sufficient to ensure that all parts are operating in a satisfactory manner at design speed and under load.

run speed

A machine’s run speed is the instantaneous operating rate at some point in time. It is stated in terms of the output rate at that time. For example, if a machine is outputting at a rate of 300 (not necessarily quality) containers per minute (cpm) at a given point in time, then that is the run speed. As the time interval increases, the output rate is always lower than the run speed due to stoppages, wastage, rework, and so on. When the output approaches the run speed for any given time period, then the line is approaching the steady-state condition. In a perfect world, the output and the run speed would be equal.


A small, flexible pouch such as might be used to deliver a single-serve portion of sugar, salt, mustard, or other condiment.


A bag-like form. The exact definition has a great many regional variants. For example, in some usage, a sack is any larger or heavy-duty shipping bag. In other usages, a sack is any large bag made from a natural or synthetic textile.


See styrene acrylonitrile.


The reduction of microbial loadings in or on articles, food, machinery, or packaging to levels considered safe by public health authorities.


A chemical agent that reduces microbial contaminants on food-contact surfaces to safe levels from the standpoint of public health requirements. Sanitizing also can be done by heating.

sans serif

A type style that has no decorative extensions at the terminal points of characters.


A Dow Chemical Company trade name for a polymeric material based on poly(vinylidene chloride) (PVDC) and its copolymers. PVDC has very low permeability to gases and vapors, which makes it an excellent barrier material for packaging. Saran is used most frequently as an applied coating to increase the barrier qualities of other base films. See poly(vinylidene chloride).


(a) When used to describe a type of chemical bond or molecule, the bonding is saturated if no double or triple bonds exist, that is, each atom is joined within the molecule to other atoms only by single bonds. (b) When describing solutions, saturation indicates that the solution is holding as much solute as the solvent can dissolve. (c) More generally describes the condition where a maximum amount of one material is present in another; for example, to be saturated with water.


The strength of a color. The extent to which two of the three red-green-blue (RGB) primaries predominate in a color. As quantities of RGB equalize, color becomes desaturated and starts to approach gray or white.



The absorption of flavor or aroma ingredients (essential oils) into the packaging material resulting in a loss of desired product characteristics.


(a) A search with a scanner for a bar-code symbol recognizable by a machine-readable code recognition system. (b) To digitize an analog hard copy of a design.

A paper sack of from three- to six-ply construction made in tubular form with each tube nested within the other. The material used for the various liners or inner plies depends on the product requirements and the transportation method to be employed. The paper is usually heavy-duty kraft from 40- to 70-pound basis weight per ply. Linings may be of specially treated papers, such as waxed paper, glassine, greaseproof or of other materials such as polyethylene as a coating or formed film, and other specialty sheets. The innermost wall is often moisture- or waterproof. The paper may be treated with resins to provide high wet-strength. In describing the construction of a multiwall shipping sack, it is customary to begin with the innermost ply.

sack, paper shipping

See sack, multiwall paper.

sack, sewn multiwall

A sack closed by sewing. Typically creped kraft tape is bound over the ends either before or after sewing.

sack, valved

A paper sack with two factory-closed ends, one of which has an opening for filling purposes. The opening is typically in the form of a tube going into the sack into which the filling spout is inserted. Product tends to close off the tube from the inside after the sack has been filled.


(a) (noun) One or more units of a product, or a quantity of a product, drawn from a specific lot or process and being reasonably representative of the product, for purposes of testing or evaluation. An individual unit in the sample is a specimen. (b) (verb) The act of taking a sample.

sample, random

In statistics, a sample obtained by a process that gave each possible combination of items in the population the same chance of being the sample actually drawn.


An electronic device for separating colors of a prepared graphic image.

scanner, wand

A handheld device for scanning and reading a machine- readable bar code. Also a light pen.

SCC 14 interleaved 2 of 5

A 14-digit machine-readable code used to provide information on goods packed within containers such as corrugated boxes. It would be scanned at manufacturing warehouses and distribution centers. The code is 6.0 inches wide by 1.63 inches high and surrounded by bearer bars. An ANSI D-grade allows it to be effectively printed on natural corrugated and other substrates that lack contrast.


(a) (noun) The crease or cut made on a paperboard to facilitate bending, creasing, folding, or tearing. (b) (verb) To make an impression or a material cut in a flat material such as paperboard to facilitate bending, creasing, folding, or tearing. See also crease.


(a) (noun) Material or product made unacceptable for its designated purpose during the manufacturing process. Includes waste and spoilage that may conceivably be reclaimed as a raw material or as a product, in whole or in part, as in scrap metal, paper trimmings, etc. (b) (verb) To retire from use, as an old machine, or a used-up product.

screen (in reference to printing)

The halftone dot pattern imposed onto a graphic image in preparation for printing. The screen is identified by the number of dots per linear inch (dpi) or the number of dots per centimetre. Screens used in package printing most often range between 65 and 150 dpi. Dots per inch is also referred to as lines per inch (lpi).

screen, dot

The individual ink dot in a halftone or process image. Dot geometry will vary depending on printing method and the nature of the image to be printed. They may be circular, rectangular (helio), elliptical, (eccentric), diamond (rugby) or in some instances combinations of two shapes (Fogra and eccentric). Monet and Samba screens are dot systems based on stochastic or frequency modulation screening.

screen angles

In color reproduction, angles at which the halftone screens are placed with relation to one another, to avoid undesirable moire’ patterns. A set of angles often used is: black, 45 degrees; magenta, 75 degrees; yellow, 90 degrees; cyan, 105 degrees.

screening test

A fast basic test to provide an initial evaluation of the suitability of a product or process.

screen roll

A roll with and etched or engraved surface used to meter and apply coatings. See roll, Anilox.

screen, line

A number defining the fineness of a halftone screen. In packaging line screens range between from 60 lines per inch for coarse work to 200 lines per inch or sometimes more for higher quality art. 100 lines per inch is about 40 lines per centimetre.

screen, stochastic

The dot patterns in halftone screens for printing, have traditionally been arranged in a straight line grid pattern and dot size is varied to produce different color densities. Stochastic screening uses a very small randomly arranged dot. The number of dots is varied to provide different color densities rather than changing dot size. When two conventional screens are printed over each other, undesirable moire’ patterns will be formed at certain overlap angles. A stochastic screening’s random pattern eliminates this problem. See also frequency modulated screening.


(a) The creation of a halftone, as in printed areas of lower optical density than that of the solid ink film, by the use of a fine pattern of ink dots. (b) The spacing between the lines of printed dots in a halftone area. See screen, line.

screening, frequency-modulated

A method of printing process art where the dot size remains constant and tonal variation is accomplished by varying the population of dots in a given area. More dots produce more color. Dot placement is random rather than in lines or patterns. See screen, stochastic.

scribe lines

Fine lines on the surface of the flexographic plate cylinder in an evenly spaced horizontal and vertical configuration to aid in the accurate positioning of printing plates. Centerline or other positioning guidelines applied to the nonprinting areas of a printing plate to facilitate mounting onto a plate cylinder.

scuff, scuffing

The action of rubbing one surface against another in a manner that causes abrasion damage. Also the damage caused by this action.

seal strength

A measure of the force required to separate a seal.


An adhesive-like material that in addition to forming a good bond to the substrate materials also is able to fill gaps.


A coating designed to prevent or retard the passage of one substance through another. For example, highly porous substrates might have sealer coats applied to reduce the absorption of adhesives, printing inks, or subsequent coatings.

sealer, L-bar

A heat-sealing device that seals a length of flat, folded film on the edge opposite the fold and simultaneously seals a strip across the width at 90 degrees from the edge seals. The article to be packaged is inserted between the two layers of folded film prior to sealing. When it is desired to cut the continuous length of sealed compartments into individual packages, a heated wire or knife is incorporated between two sealing bars that form the bottom of the L. These bars then make the top seal of the filled bag and the bottom seal of the next bag to be filled.

sealing surface

(a) The surface to which a seal will be made. (b) The surface of the finish of the container on which the closure forms the seal. See land.

sealing, dielectric

A sealing process widely used for vinyl films and other thermoplastics with sufficient dielectric loss, in which two layers of film are heated by dielectric heating, and pressed together between applicator and platen electrodes. The films serve as the dielectric of the so-formed condenser. The applicator may be a pinpoint electrode as in “electronic sewing machines,” a wheel, a moving belt, or a contoured blade. Frequencies employed range up to 200 MHz, but are usually 30 MHz or less to avoid interference problems.

sealing, heat

Any method of creating a seal using heat. These include fusing plastic together by melting together at the interface or by activating a preapplied heat-activatable adhesive substance. See also sealing, dielectric, sealing induction, and sealing, ultrasonic.

sealing, hot-wire

A sealing method using a hot wire to heat and fuse the plastic material. Hot-wire sealing is used mostly with materials such as polyethylene. The sealing action simultaneously cuts through and separates the film.


(a) (noun) A continuous joint of two surfaces such as might be made by fusion or adhesive. (b) (verb) The act of making a seal.


(a) The ease with which a seal can be made. (b) capable of being sealed.

seal, chevron

Most flexible pouches have a straight heat seal going across the end of the pouch. A chevron seal is in the form of a broad V with the point of the V nearest the package edge. Because of this geometry, a chevron seal has two wide unsealed tabs above the seal extending along each side of the package. These provide large gripping areas that can be used to easily peel the pouch apart. Such ease of opening is particularly important for medical supplies.

seal, cohesive

A seal produced by an adhesive that adheres only to itself and requires only contact pressure to bond. Also known as cold seal.

seal, crimp

A method of heat-sealing thermoplastic-coated papers or thermoplastic films with the pressure exerted by knurled wheels or bars having a corrugated surface.

seal, flat

A heat-seal characterized by being flat. Compare with crimp seal.

seal, hermetic

A seal that will exclude air and be gastight at normal temperatures and atmospheric pressures.

seal, identifying

A device that carries a mark, brand, insignia, or sales story, attached or applied to a package or merchandise for purposes of identification or attention.

seal, lap

A type of seal resulting from overlapping and sealing together edge areas of two sheets, usually by heat, resulting in a flat seam area. Lap sealing requires that the inside surface be able to heat seal to the outside surface. See fin seal.

seal, safety

A tamper-evident seal.

sealing, impulse

A heat-sealing technique in which a surge of intense heat is momentarily applied to the area to be sealed, followed immediately by cooling. Impulse sealing is most commonly used on monolayer polyethylenes.

sealing, induction

A sealing method, most commonly used over a bottle opening, and made by exposing an aluminum foil coated with a thermoplastic adhesive substance to an electrical field. The field induces eddy currents, which heat the aluminum foil, melting the adhesive material that in turn adheres the aluminum foil to the bottle’s opening circumference. Induction seals provide tamper evidence and a hermetic seal when used as an innerseal beneath a normal threaded closure.

sealing, solvent

A method of bonding packaging materials, which depends on the use of small amounts of volatile organic liquid to soften the coating or surface of the material to the point where the materials will adhere.

sealing, ultrasonic

The application of ultrasonic frequencies (20 to 40 kilohertz) to the materials being sealed together. The vibration at the interfaces generates enough localized heat to melt and fuse thermoplastic materials.


The juncture created by any free edge of a container material where it rests over another material. Seams may be adhesively bonded, heat-sealed, stitched, taped, or joined by other means.

seam, bead

A seam where two materials are joined together along a very narrow bead without overlap of the materials.

security band

A plastic band that is shrunk in-place around the closure of a bottle so that the closure cannot be removed without first damaging the neck band. Poly(vinyl chloride) is one of the more common materials used for this application. See tamper- evident.


Surface that stick to themselves when brought into contact. Sometimes called contact cement or a cold seal.


A machining process where part of the process is controlled by the action of a human.

semirigid packaging

A package that is able to reasonably support itself, but whose shape or volume may change if pressure, vacuum, or some other force is applied. Plastic bottles are the best example of a semirigid package form. Since the bottle volume can change, the fill volume of a semirigid package usually is measured external to the package. Compare to rigid and flexible packaging.


A transducer whose input is a physical phenomenon and whose output is a quantitative measure of the physical phenomenon.

sensor, contact

A device capable of sensing mechanical contact.

sensor, proximity

A device which senses that an object is a short distance (e.g., a few inches or feet) away, and/or measures how far away it is. Proximity sensors work on the principles of triangulation of reflected sound, intensity-induced eddy currents, magnetic fields, back pressure from air jets, etc.


A set of three or four continuous-tone or halftone analog or digital records of a full color image. Each record represents one of the process colors abstracted, and is used to make a printing plate in the respective color.


A font style with decorative extensions at the terminal points of characters and varying line thicknesses in the letter design.


A name sometimes applied to screen printing.


Saw-tooth. Used to describe the configuration frequently used on heat-sealing equipment for obtaining a crimp seal.

serrated edge

A saw-tooth edge, such as that around the mouth of a paper bag. The serration is made tearing the paper tube against the serrated edge of the metal former on the bag machine.


To harden into a final form from a fluid or semisolid state. Materials such as coatings or adhesives can set by a variety of mechanisms including water loss, solvent loss, chemical reaction, and polymerization. See also cure.


Inks or coatings that have transferred to the back of adjacent materials.

setting temperature

(a) The temperature to which an adhesive or assembly is subjected to set the adhesive. (b)The temperature attained by the adhesive.

setting time

Of adhesives or thermoset plastics, the time from application, mixing, or initiation until the material has become firm and handleable and will no longer flow by gravity.

setting up

Initial drying of a coating, ink or adhesive by solvent release.

set up

To prepare a machine for a production run. Also make ready.


A color produced by pigment or dye with some black mixed in it, therefore darkening it. Opposite of tint.


In printing, the acuteness of a printed edge. That factor that describes the steepness or abruptness of an edge in a print or photographic image.


An action resulting from applied forces, which causes or tends to cause two neighboring parts of a body to slide relatively to each other in a direction parallel to their place of contact.

shear cut

The cutting of a continuous web of material by an action similar to that of a scissors.

shear strength

(a) The ability of a material to withstand shear stress. (b) The stress at which a material fails in shear.

shear stress

A stress applied to a material parallel to its plane. Tensile stress is a stress applied perpendicular to the plane. For example, an adhesive bond can be separated by pulling perpendicular or parallel to the adhesive layer.


(a) Plastic or other material that is in the form of flat sheets as opposed to being wound into a roll. (b) A flat plastic material that is of heavier caliper than film, generally taken to be more than 25 micrometres (0.001 inch) thick.


Any process that is fed one flat sheet at a time rather than from a roll.


A machine that cuts a continuous web of paperboard, paper, or film into rectangular sheets of uniform lengths.

shelf life

In general, the expected time within which the quality of a product is acceptable. The exact definition of the end-point can vary considerably. For example, it can mean the point at which the product should have been transferred to a consumer, or it may mean the point at which the product should no longer be consumed.


A product that can be stored for extended periods at ambient conditions without the need for refrigeration or other special storage conditions.

shelf talker

Small tags affixed to the display shelf edge in a retail establishment.

shell cup

A device for measuring viscosity by timing the flow of a specified amount of fluid through a calibrated orifice. See also efflux cup and Zahn cup.


An alcohol-soluble natural resin used in flexographic printing inks and as a primer for aluminum foils.

shore hardness

A method of measuring hardness by noting the degree to which an indentation can be made into the substrate material.

short, shortness

(a) An adhesive or inks that have little tendency to string, generally an fluid with low tack. (b) The property of adhesive filaments to break apart quickly and cleanly without stringing or webbing during application and spreading. Opposite of long.


Undesired visibility of printing from the opposite side of the sheet to which the impression was made. Usually a result of a translucent or too thin sheet.

shrink band

A band or strip of plastic used to combine two or more objects into a single unit. May also refer to a secondary closure or seal made from a plastic film that can be shrunk with heat after being applied.

shrink film

A plastic film that has been stretched in one or two directions and chilled in such a way that the plastic retains a memory of its original shape and will shrink toward that shape if re- heated. Shrink films are applied to objects, and after heating, provide a tight, contour-fitting unitizing sleeve, band, or wrap.

shrink packaging

A method of wrapping articles using plastic film that has the property of shrinking when heated. The object to be shrink wrapped is sealed in a loose envelope of the film and then passed through a heated tunnel to shrink the material into close conformity with the object.

shrink tunnel

A heated tunnel mounted over a conveyor belt. Packages loosely wrapped in shrink film travel through the tunnel to shrink the film snugly around the wrapped object.

shrink wrap

A plastic film, typically polyethylene, polypropylene, or poly(vinyl chloride), that is wrapped loosely about another container or product and then made to shrink and conform tightly about the container or product by the brief application of heat. Shrink films can be produced having biaxial or uniaxial shrinkage. Biaxial shrink film is most commonly used as package or product over-wrap while uniaxial shrink film is most commonly used for shrinkable label applications and for tamper evident neck-bands.


Unexplained reduction in physical inventory. Shrinkage sources include theft, unrecorded damage and disposal, short shipment, errors in accounting, bookkeeping, and physical inventory counting. Also called shrink.


A loose fitting product cover designed to isolate the product from outside contamination and influences.

side seam

The joining of two edges along the narrow side of a package.


Leakage of powdered or finely ground material through seams or joints in a container.


Said of a pouch, bag, carton, or other container that is able to hold finely divided dry product without leakage.


In the production of most packages, the customer will sign- off at various stages of the development process. The sign- off indicates the customer’s satisfaction with the completed step and authorizes the expenditure of money for the next step. Sign-offs are regarded as legal commitments and should be treated as such. In the production of a package for example, the customer may be asked to sign off at some or all of the following steps: hand sample, original artwork, cutting die, prepress proofs, and finally, press proofs.

silica gel

A colloidal silica having a great affinity for moisture, used as a desiccant to absorb moisture inside packages. Silica gel saturated with water can be reactivated by heating to temperatures above 100oC (212oF).

silicone polymer

Polymers composed of molecular chains containing alternating silicon and oxygen atoms. These can be liquids or solids depending on the molecular weight and the groups attached

to the chain. Silicones also can have widely differing properties. For example, some silicone compounds are able to be used as adhesives, while others are used as anti-adhesive or release agents.

single-site catalyst

A catalyst used to produce various hydrocarbon polymers having a narrow molecular weight spread. Also known as metallocene catalysts. See metallocene.


An inclusive term for silicone oxide used in reference to the coating of plastics. See coating, glass.

SI System

SI stands for Systeme d’unites Internationale and refers to the international standard metric system based on the metre, kilogram, second, ampere, and degree Kelvin.

size, sizing

(a) In paper and paperboard manufacturing, resin, alum, starch, and similar materials added to pulp or applied as surface coatings to provide functional characteristics, most notably that of liquid holdout. (b) The treatment of a surface intended to fill up pores in the material surface.


The dry film layer that occasionally forms on emulsion or solvent-type adhesives, inks, paints, etc. This action is caused by localized evaporation of solvent from the surface of the liquid.

skin packaging

A package where the product is covered and secured against a paperboard backing card with a thin, tough, plastic film. The article is usually placed on the backing card and a soft heated film is draped over the article and card. A vacuum draws the film down tightly over the part. A heat-reactivated adhesive substance bonds the film to the backing card.


The formation of a dried surface layer over an adhesive, ink, or other compounded material subject to drying. Skinning may occur in the bulk container or over the film after application due to the rapid evaporation of the solvent carrier.


(a) Missing dots in rotogravure printing, usually in the light tones. Often counted as skipped dots per unit area when viewed microscopically. (b) The absence in some areas on the substrate material of an applied coating or adhesive.


See stock-keeping unit.


A paper containing a small amount of sizing resin. Such a paper would be very water absorbent. Opposite of hard-sized. See size, sizing; paper, unsized.


A tubular form, open at both ends, that is slipped over an item or package.

slide closure

into narrower widths. Most commonly, web stock is unrolled past a series of knives set to the correct widths, and the slit web rewound back into roll form. In-line slitting is done immediately after a production or printing unit. More commonly though slitting is done off-line.

slug (as used in reference to printing)

A small piece of flexographic printing plate used to print variable information. The slug can be removed and another inserted into its place without the need for producing a new plate.


A printing defect caused by slippage at the moment of impression between the substrate, plate, or blanket.

snack pack

A package that contains a small portion product or several related products sufficient for a single person but less than a full meal.


See hickey and picking.

softening point

The temperature at which a plastic material will start to deform with no externally applied load or under some predetermined load. It is not a clearly defined value. The actual softening point may be defined in many ways, most of them arbitrary. For example, the Vicat softening point (ASTM D 1525) defines the temperature at which a flat-ended needle will penetrate a substance 1 millimetre. The ring and ball test defines the temperature at which a specified size ball will drop through a circular disk of the material being tested.

solid bleached sulfate (SBS)

A paper or paperboard material made entirely from bleached chemical pulp and with a clear white appearance throughout. Used extensively in the food, cosmetic, and pharmaceutical industries.

solid unbleached sulfate (SUS)

Paper or board made entirely from unbleached chemical (kraft) pulp. It is the strongest of the packaging papers.

solids content

The amount of nonvolatile component remaining in an adhesive, ink, or other coating material after all volatiles are removed, expressed as a percentage of the original mixture. Also referred to as the nonvolatile content.


A liquid medium able to dissolve a substance and place it in solution. Solvents are widely used to dissolve solid resins in order to produce a fluid base, which might subsequently be used to manufacture adhesives, coatings, and inks. In other instances, solvents may be used to dilute, render more fluid, or control the viscosity of a composition. Major solvent family groups are alcohols, esters, glycol ethers, ketones, aliphatic and aromatic hydrocarbons, and chlorinated hydrocarbons.

A closing system used on flexible package pouches and bags wherein a continuous extruded rib is pressed into a matching channel by means of a sliding mechanism. See also ziplock.


The property of a plastic having a relatively low coefficient of friction.

slip additive

Additives used in inks or varnishes to improve slip (reduce coefficient of friction).

slip sheet

A sheet used to prevent blocking in a roll or stack.


To cut a web to a specified width.


Slits in the carrier or release liner of a pressure-sensitive label to make hand removal easier.


A machine to cut roll stock in the long direction. Three types are widely used: razor blade slitter; shear slitter; and score cutter.

slitter cuts

Small cuts made in the paper while forming a tube on a paper bag machine, prior to and necessary for the formation of automatic and satchel-bottom bags.

slitter, razor cut

A simple slitter based on passing a plastic web past a stationary razor edge. Not used with high speed paper slitters.


A machine that slits stock from a master roll in the machine direction and rewinds the narrower width bands into individual rolls of a specified width.

slitter, shear cutThe most common method of slitting flexible packaging materials using a shear cutting action similar to a pair of scissors. The device is typically made up of a powered bottom knife that has a supporting ledge for the film. The beveled-edge slitter slightly overlaps the bottom knife. A web is slit by passing between the two.

solvent, aromatic

Any solvent containing a benzene ring. Most common aromatic solvents are benzene, toluene, and xylene.

solvent cementing

See bonding, solvent.

solvent, fast

A quick-drying solvent. One that has a high evaporation rate. Also termed a rapid solvent. Opposite of a slow solvent.

solvent, polar

Solvents such as alcohols and ketones that contain hydroxyl, carbonyl, or other polar groups. The molecules have an uneven distribution of electrons about their geometry, resulting in positively and negatively charged ends. They have high dielectric constants.

solvent, residual

Solvent remaining in a finished product after the manufacture has been completed. Solvent-based adhesives, coatings, and printing inks are the most common sources of residual solvents. Residual solvents can produce undesirable flavors or aromas, and can pose health risks.

solvent resistance

That property that allows a material to resist changes in properties when exposed to a solvent. Although water is a solvent, the term “solvent resistance” normally refers to unspecified organic solvents, usually common alcohols and hydrocarbons. The term has meaning only when the solvents to which the material is resistant are named.

solvent retention

An undesirable condition where solvent retained in the substrate after drying. See solvent, residual.


Acronym for standard operating procedure.


The process of one substance taking up and holding another by physical or chemical action. Usually the sorbed substance is mobile, for example, a gas or vapor, and the sorbing phase is a liquid or solid.

sorption isotherm

A statistical curve for any given product plotting equilibrium relative humidity against moisture at a constant temperature.


See bag, self-opening square.

source reduction

The elimination or reduction of the weight of packaging. Reduction is the first priority in a program to improve the environmental performance of a packaging system. Some definitions of source reduction also include the elimination of toxic materials used in packaging. Source reduction is one of the four Rs of environmentally responsible packaging; the other three being reuse, recycle, and recover.


The precipitation or coagulation of ink ingredients due to the presence of water or other foreign materials.

sous vide

A food packaging technique in which a partially cooked food is placed in a vacuum barrier package and the sealed package is then pasteurized. The package product is distributed and stored under refrigerated conditions.


The lighter element of a bar code formed by the background between the printed bars.

space width

In bar coding, the thickness of a space measured from the edge closest to the symbol start character to the trailing edge of the same space.

specific density

A now rarely used term to describe relative density.


A document or set of documents detailing the exact dimensional, aesthetic, functional, and performance requirements of each component in a packaging system and of the assembled system. Specifications also will detail how the individual characteristics will be measured and list causes for rejection.

specification, performance

A specification that describes the desired measurable performance characteristics of the completed container system or subsystem rather than specifying, in detail, the materials of construction.

specification, product

The written description of the required product characteristics at the end of any manufacturing phase or of the final completed product.


A photoelectric device for measuring color values by means of recording the intensity of reflected monochromatic light at each wavelength from 400 to 700 nanometres.

spectrophotometric curve

The color graph produced by a spectrophotometer.

spectrum, electromagnetic

The entire spectrum ranging from the long wavelengths of radio waves to short gamma rays. This includes in descending order of wavelength: microwave, radar, infrared, visible light, ultra violet, and x-rays.

spectrum, visible light

The series of colored bands diffracted and arranged in the order of their respective wavelengths by passage of white light through a diffracting medium and progressing continuously from red (the longest wave visible) to violet (the shortest). That part of the electromagnetic spectrum detected by the human eye.


The rate per unit time at which an event occurs or the rate per unit time at which object or material is moving.


An aggregate of polymer crystals present in most crystalline plastics. The aggregates are typically rounded and fibrous in appearance and can range in size from micrometres to several millimetres.

SPI code

The code developed by The Society of Plastics Industry, Washington, D.C., to identify the base family to which a plastic belongs for purposes of sorting and recycling. It consists of one of seven digits, each identifying a plastic family, inside a triangle of chasing arrows. The polymer initials are placed under the symbol. The plastic families are identified as follows: 1, PETE; 2, HDPE; 3, V; 4,LDPE; 5,PP; 6, PS; 7, OTHER.


Joining two pieces of web material to form a continuous web. Film splices may be butted or lapped using tape, adhesives, ultrasonic welding or other means.

splice, butt

An end-to-end join of two similar materials usually using tape. A butt splice usually requires that the web be stationary at the moment of splicing.

splice, flying

A splicing or joining of two web materials while the materials are in motion.


A mandrel that can be used for winding and unwinding continuous webs.


The undesirable presence of ink or dirt in a space.

spot color

A specified color (for example, one chosen from a PMS color book) used instead of combining the four process colors.


Enlargement of the printed image compared to the printing plate. More commonly known as gain. See dot growth.

spreaderAny of several devices such as would be used on a slitting machine to eliminate baggy areas and wrinkles before entering the slitters. If the web is not surface sensitive, the spreader may simply be a bowed pipe which can be rotated to appropriate angles. If the material is surface sensitive, then a rubber- covered bowed rotating roll such as the Mount Hope roll is used. See roll, Mount Hope.

spunbonded sheet

A sheet material resembling paper made by heat bonding fine strands of randomly arranged, continuous thermoplastic fibers. The most common of these materials is Tyvek, marketed by Du Pont. Spunbonded materials are clean, have excellent all-directional tensile and tear strength, and good flex life, water resistance, and puncture resistance. Applications include, medical packaging, envelopes, and industrial bags and sacks.

SSCC 18 bar code

A machine-readable code that uses UCC/EAN 128 symbology and is used as a secondary bar code along with SCC-14 on shipping containers or as the primary bar code for variable or serial information. The compact format allows for added information such as weight and count to be included in the scanned information. SSCC stands for Serial Shipping Container Code.


The durability or constancy of properties under expected use conditions.

stability, dimensional

A material’s ability to retain its dimensional shape under processing or use conditions such as humidity and temperature. The degree to which dimensional changes occur in a particular material under controlled conditions is frequently measured in terms of its expansion and contraction.

stability, heat

The resistance to change in color, dimension or other characteristic as a result of heat encountered by a material or product either during manufacture or in service.

stability, light

(a) The ability of a pigment, dye, or other colorant to retain its original color and physical properties either alone or when incorporated into plastics, inks, and other colored films or surfaces, when exposed to sun or other light. (b) The ability of a plastic or other material to withstand the deteriorating effect of exposure to sun or other light that results in physical material changes such as embrittlement.

stability, storage

The ability of a material or product to be stored for extended periods at ambient conditions without significant property changes.


An additive used to assist in maintaining the physical and chemical properties of a material at their initial values throughout the processing and service life of the material.


Having a chemistry not easily subject to change, as well as not easily altered by temperature, humidity, or mechanical manipulation. Having constant properties.

stain resistance

A material’s ability to resist discoloration when exposed to product, solvents, or other chemicals or conditions.


An undesired discoloration of material.


A document, object, or material that defines nomenclature, dimensions, relationships, physical appearance, performance, or test methods.

standard brightness

A standard adopted by the paper industry originally for grade differentiation, specification, and control. It is expressed as reflectively for blue light when measured on instruments employing C.I.E. geometry with specified spectral geometric and photometric characteristics. It is sometimes call G.E. Brightness after the manufacturer who made the original instruments. See paper brightness.

standard temperature and pressure (STP)

For development purposes, standard temperature and pressure are 20oC and 760 millimetres of mercury.

star target

A printed circular test image containing alternating light and dark wedges that meet at a central point, used to monitor press performance. Excessive gain will fill in the center of the star.


The main carbohydrate found in plants such as sago, wheat, corn, potatoes and tapioca. Starch is used as raw material for adhesives, for sizing paper, and as an adhesive for corrugated material.


A defect on a roll of material characterized by star-like patterns on the roll ends. Usually caused by improper tension during winding, typically softer inner layers being squeezed together by more tightly wound outer layers.

start and stop characters

The characters at the beginning and end of a bar code, that signal the scanner the kind of bar code being scanned, what direction to read the code, and where the scan is to start and stop.


Bound electric charges on the surface of an insulating material. With reference to films, causes them to cling to one another or to other insulating surfaces as well as attracting atmospheric dust. Static can disrupt the even application of ink to a surface.

static cling

The tendency for materials that have acquired a high static electrical charge to cling to itself or to other materials.

static decay

A measure of the rate at which a statically charged material will dissipate its charge. In the more common test methods, the end point is taken as a value that is 10% of the initial charge.

static dehumidification

Any process wherein the control of relative humidity in a container is based upon the use of desiccants and barrier materials having a low water vapor transmission rate.

static dissipative agent

A substance applied to the surface or incorporated into a plastic whose function is to render the surface less susceptible to accumulation of electrostatic surface charges. Such charges can attract dust or dirt to the material surface or affect the laydown patterns of printing inks. The discharge of as little as 1000 static volts through a microcircuit can destroy it. All nonconductive materials are capable of generating a static electrical charge to varying degrees. Also referred to as an antistatic agent. See triboelectric series.

static dissipative material, static dissipative packagingA material or package able to dissipate static electrical charges at a rate that will not damage static-charge sensitive electronic circuits. Static dissipative plastics typically will have additives or treatments that slightly increase the conductivity of the plastic. These treatments include additives that bloom to the surface, incorporation of small amounts of conductive carbon pigmentation and lightly metallizing the material’s surface.

static electricity

A stationary electrical charge developed on a material as a result of an accumulation or deficiency of electrons in an area. All insulating materials are capable of developing and holding a static charge. Depending on the material, the tendency may be greater or smaller and may favor the positive or negative. Arrangement of materials in a table according to their tendency to develop a charge and the nature of the charge is a triboelectric series. The further apart two materials are in the series, the greater the tendency to generate and hold a charge when rubbed against each other. See triboelectric series.

static eliminator

A device for neutralizing static electricity.

static load

The force on a package or structure resulting from the mass (weight) resting on it. Compare to a dynamic load which is the rapid application of a compressive load.

static neutralizer

A device used on printing presses and coater/laminators that removes static electrical charges from the moving substrate material. High static charges can cause problems with ink transfer and material feed systems, and can attract dust particles to the surface of the substrate material.


A location on a machine or production line where a specific activity or operation takes place.

statistical process control (SPC)

The application of statistical methods to continuously monitor production and output characteristics. The purpose is to identify and reduce sources of product-quality variation and output-quality limiters in the production process. The objective of statistical process control is to build quality into the process rather than to remove defective items by inspection. SPC systems have many variations and terms associated with them. For example, quality circles, total quality management (TQM), and zero defect programs will have an SPC program at their core.

statistical quality control

The use of statistical techniques for process control or product and package inspection. It also includes the use of experimental design techniques for process improvement.


A collection of quantitative data useful for analyzing, interpreting, and establishing a course of action.


(a) The act of positioning and exposing multiple complete images on film in preparation for platemaking. (b) Equipment for performing this function.


An agent used to achieve commercial sterility.

sterile zone

The controlled area in a factory or the zone within a machine where sterile operations are carried out.

sterile, sterility

Free of any active or dormant viable microorganisms.

sterility, commercial

The condition achieved by heat and other treatments to render the food free of pathogenic microorganisms capable of growing at normal non-refrigerated conditions.


The ability to withstand contact with steam (moist heat) at 30 pounds pressure for 30 minutes, or contact with dry heat (circulating hot air) at 2000C for 15 minutes, or contact with ethylene oxide gas at specified temperature and pressure cycles. These processes would allow an article to be made free from living microorganisms. Sterilizing agents may be steam, dry heat, gamma rays, gas, or chemical sterilants.


Hot-melt residues remaining in repulped paper recyclate. During the drying of the paper, the hot melts can be reactivated and will stick to drying drums, tearing the paper web in the process.


Double-faced adhesive-coated material used for mounting elastomeric printing plates to the plate cylinder.


Rigidity; resistance to bending. The capacity of a structure to resist elastic deformation under stress.

stock-keeping unit (SKU)

An individual unique item of warehousing or inventory. Every size, flavor, style of the same product constitutes a stock- keeping unit. Each SKU would require a unique Universal Product Code (UPC).


See standard temperature and pressure.

(a) (noun) A mark, lettering, or design produced by stenciling, for example as by screen printing. (b) A suitably perforated sheet, board, or plate through which ink or other coloring flows to make a printed impression. (c) (verb) To letter or mark a design by means of ink applied through a cut-out stencil board.

straight-line configuration

A packaging machine configuration in which all actions are performed in-line with one another. Most typically, a conveyor transports the package from station to station and then stops while an action (for example, fill, close, label, code) is performed. The start and stop nature of the process limits the production speed.


(a) In tensile and compression testing, the ratio of the elongation to the gauge length of the test specimen, that is, increase (or decrease) in length per unit of original length. (b) Used to indicate that a part or the internal molecular structure of a part is in a condition of strain.

strain, residual

Strain remaining in a part that has been chilled while undergoing plastic deformation or immediately after. Often, if the part is reheated, some or nearly all of the strain may be recovered. Usually associated with residual stress.


Streaks in the printing, usually caused by poor wiping of the gravure cylinder or excess water in litho ink.


(a) The mechanical properties of a material which allow it to resist distortion or parting under an applied load. Strength properties include toughness, tensile strength, flexural strength, tear strength, compressive strength, and so on. (b) Intensity of color of a printing ink.


The force producing or tending to produce deformation in a body, divided by the area over which the force is acting. If the stress is tensile or compressive, the area is perpendicular to the stress; in shear it is parallel to the stress. The SI unit of stress is the pascal (Pa) equal to 1 newton per square metre (N/m2).

stress concentration

The magnification of applied stress in the vicinity of a notch, hole, inclusion, or inside corner. Minimizing stress concentrations is an important aspect of plastics product design.

stress relaxation

The decay of stress over time at constant strain. If a plastic specimen is strained and the recovery of the strain prevented, the chain segments of the molecules will tend to realign so as reduce the strain. The elastic and retarded strains that would usually be recovered on release of the stress are, instead, converted into unrecoverable strains when chain segments have been rearranged. The strains induced during processing of molten thermoplastics, particularly injection molding, often do not completely recover before cooling and become frozen into the material. These strains may slowly recover at ambient temperatures resulting in warping or excessive part shrinkage. For this reason, moldings with high molded-in strain are sometimes annealed. ASTM D 2991 describes a standard practice for testing stress relaxation of plastics.

stress relieving

Uniform heating of a structure to a sufficient temperature to relieve the major portion of the residual stresses, followed by uniform cooling.

stress whitening

Whiteness seen in some plastics that are subjected to extreme stretching. The whiteness is thought to be due to the formation of light-scattering microvoids (microcavitation) within the material.

stress, internal

Stress created within a material, such as might happen during rapid cooling, or by different rates of expansion or contraction. Internal stress usually will detrimentally affect many strength characteristics and may lead to reduced performance or failure. For example internal stresses in plastic parts can cause part deformation, cold flow, and fracture.

stress, residual

Stress remaining in a plastic part that has been chilled quickly during or after forming. The stress remains because there was too little time for the molecules to move and relax while the material was soft. Over time, high residual stress can cause parts to warp, shrink, or crack. Stress can be relieved by slower cooling or by holding the part briefly at some intermediate temperature. See annealing.


(a) Extensibility of web materials under tension. Stretch usually is determined in tensile-testing equipment and is recorded as the percentage of extension at the point at which the sheet breaks. b) The elongation of a design in a rubber plate when mounted around a cylinder.

stretch wrap

The use of stretch film to tightly wrap a package or a unit load in order to bind and immobilize it for further handling or shipping.


A pattern of lines or streaks caused by uneven application of an adhesive, ink, or other material, usually in the direction of the web movement.


Penetration of ink through the substrate. Strike-through is caused by ink penetrating through the sheet, sometimes because of pinholes. Usually measured three hours after printing.


The property of an ink or adhesive that causes it to draw into filaments or threads.

strip heater

An electrical heating device provided with mounting tabs at each end for air-heating applications and for clamping to surfaces to be heated, such as sealing bars or rounded surfaces. Also used in such applications as hot plates, platens, dies, printing-press dryers, etc.

strip packaging

A package made by enclosing an object to be packaged, such as a tablet, between two webs and then sealing the webs together so that the seal completely surrounds the object being packaged.


An electronic flash tube that produces hundreds or thousands of flashes of light per second. It is used to freeze images of moving objects for vision systems.

styrene-acrylonitrile (SAN)

Any of a group of copolymers containing 70 to 80% styrene and 30 to 20% acrylonitrile. Styrene-acrylonitrile has higher strength, rigidity, barrier, and chemical resistance than straight polystyrene. The material’s cost limits its application to those requiring its specific property combinations. Barex (a polyacrylonitrile) is a variation of a SAN-type polymer available from BP Chemicals, Cleveland, Ohio. Butadiene may be copolymerized or added to SAN to produce acrylonitrile- butadiene-styrene.


These polymers are a family of block copolymers containing a higher percentage of styrene than butadiene. They are recognized for their transparency, high impact strength, and good integral hinge properties.


The process whereby a solid is volatilized by heat without passing through a liquid phase.


The material on which some action, such as printing, coating, adhesive bonding, and so on is being performed.

subtractive synthesis

The synthesis of various colors by the subtraction of selected wavelengths from an impinging white light.

sunlight resistance

The ability of a material to resist changes when exposed to sunlight, most particularly those wavelengths in the ultraviolet region of the spectrum. A particularly important material property for packaging that will be exposed to direct sunlight for extended periods.


A condition in which a solvent, contains concentration of a substance higher than it can normally hold at a given temperature and pressure. Thus, a solution that is saturated at 90oC may become supersaturated when its temperature decreases, unless there is crystallization or sedimentation of the solute held in excess. Seeding the supersaturated solution with the solid solute or the presence of other solid particles will start crystallization.

supervisory control and data acquisition (SCADA)

A software system typically configured to provide human- machine interface (HMI) capabilities to the packaging line. SCADA systems can be configured to provide static and dynamic representation of the current state of each machine on a packaging line. Functions such as speed change, start, stop, recipe download, and reporting are typical SCADA capabilities. SCADA systems act as the information bridge for real-time packaging data to the manufacturing execution and other information management systems.

surface active agent

A substance which is strongly attracted to other surfaces and by doing so modifies their properties, for example, changes the surface tension of a liquid. Wetting agents and detergents are forms of surface active agent. Also known as a surfactant.

surface resistivity

The numeric equal of the surface resistance between two electrodes forming opposite sides of a square. The size of the square is immaterial. Surface resistivity is a critical value when qualifying static dissipative materials. The deposition of aluminum on paper by vacuum metallizing is quantified by surface resisitivity.

surface strength

The resistance paper offers against rupture or breaking away of its surface fibers during printing. Separation forces acting perpendicular to the surface of the paper are generated as the sheet leaves the printing nip and/or is peeled off the inking surface.

surface tension

Basically a measure of the attractions surface molecules have for each other. Surface energy and surface tension are equivalent terms, but with liquids it is possible to measure the surface tension directly. The unit in common use is dynes per centimetre, equal to 0.001 newton per metre. Surface energies of solid materials such as plastics are determined indirectly by observing the angles of contact of a graded series of increasingly polar liquids of known surface tension on the plastic surface. (See ASTM D 2578).

surface treatment

Any method of treating a polymer to alter the surface, rendering it receptive to inks, adhesives, and coatings. Most commonly, plastic surfaces are modified by flame or corona discharge treatment. These oxidize the surface slightly and provide the necessary polar sites that contribute to good bonding. Polymers can also be chemically treated.


A “surface-active” chemical that reduces the surface tension of a liquid (typically water) in which it is dissolved, making it easier for the solution to wet solid surfaces and penetrate pores. Also wetting agent, surface active agent, or detergent.


A lightly vacuum-metallized material that converts local microwave energy into heat energy. Susceptor films or patches are used in such applications as helping complete popping of popcorn and to produce browning and crisping of microwave pizzas.


Dispersion of very fine particles of a solid or liquid in a liquid or gas, respectively, in which the suspended material is not actually dissolved, but will settle out on prolonged standing unless prevented by agitation or by the use of stabilizing agents. A suspension differs from a colloidal condition by this property of settling; a colloid does not settle.

Sutherland ink-rub tester

A device for testing rub resistance of an ink.


An increase in volume due to the absorption of a liquid.

swelling resistance

Ability, usually of a plastic, to resist increase in size due to contact with chemical agents.


A material that has been substantially produced by chemical processes rather than from natural sources. The division between natural and synthetic is vague since many natural materials are subjected to varying degrees of chemical processing prior to use.

synthetic resin

Resins that do not occur naturally such as those produced by synthesis of organic chemicals.


A projection or small area, usually to assist in the lifting or separation of parts. See tear tab.

Taber stiffness tester

A test instrument and method to measure the resistance to bending of materials such as paper or paperboard.

table pack

tail end 125 Perceived by touching, or having the sense of touch.


(a) (noun) An identification device, usually made from a heavy paper stock that is only loosely or partly attached to the product. The attachment is hung over or on some part of the product by string, metal wire, or other material, or affixed by other physical means. (b) To apply a tag. In this sense includes electronic article surveillance (EAS) tags.

tag activator

A device that changes the state of an electronic article surveillance (EAS) tag already placed in or on a product from non-detectable (inactive) to detectable (active). Its function is referred to as “waking up” an inactive tag.

tag, active

An electronic article surveillance (EAS) tag capable of responding to a detector and making its presence known. An active tag is also referred to as being live or awake.

tag, conventional

The process of placing an electronic article surveillance (EAS) tag on the exterior of the merchandise package so that it is visible to the consumer. Also is known as overt or topical tagging.

tag, covert

The application an electronic article surveillance (EAS) tag to a package or product in such a way as to make it unrecognizable to the consumer. This can include tags hidden in the product or package or disguised in an exterior application.

tag, dead, killed

A deactivated electronic article surveillance (EAS) tag.

tag, electronic article surveillance

An electronic article surveillance (EAS) device that is attached to package or product, and which will set off an alarm when the active device is passed through an EAS detection system.


A unique overt but identifiable substance added to printing inks as a way of identifying counterfeit packaging.

tag, inactive

An inactive electronic article surveillance (EAS) tag that could not be detected by an EAS detection system.

tag, smart

An electronic tag that communicates discrete product information to a receiver. Smart tags can be made to function as an electronic article surveillance (EAS) device.

tail end

Usually the end of a material as it is unwound from a roll.

A package designed so that it can be used directly from the unit of sale. A general design feature of such packs is to make them esthetically pleasing by enhancing decorative features and reducing the prominence of commercial messages.

tack, tackiness

In adhesives, the amount of stickiness or pull resistance experienced when one attempts to separate two substrates while the adhesive is still in a viscous or fluid state. Similarly in printing inks. Related to the material’s cohesion properties.

tack force, tack strength

The force required to separate adhesive from a surface while it is still in a wet or uncured state.

tack range

The period of time during which an adhesive will remain in a tacky condition and capable of wetting out and bonding to a substrate after application to an adherend.

tack time

Time required for an adhesive to develop enough initial strength to hold two surfaces together.

tack, dry

The tackiness of an applied adhesive such as a pressure sensitive adhesive after the volatile components have evaporated or been absorbed.

tack, hot

The stickiness of a heat-activated or hot melt adhesive at melt temperatures.

tack, initial

The holding power of an adhesive immediately after application.

tack, prolonged

A property characterizing certain heat-sealing adhesives, which retain their tackiness for a prolonged, period after cooling.


A substance such as a rosin ester that is added to synthetic resins or elastomeric adhesives to improve the initial tack and extend the tack range of the deposited adhesive film.

tamper evident (TE)

Tamper evident is described in CFR 211.1323 as: “ ... having and indicator or barrier toward entry which, if breached or missing, can reasonably be expected to provide visible evidence to consumers that tampering has occurred.”


The act of intentionally and illegally entering into a packaged product and altering the contents in any manner. In many instances, tampering is merely a nuisance or annoyance. In its extreme form, tampering is aimed at harming the health of the user.


Proof is an absolute term suggesting that a package could never be tampered with. Since this is almost never true, the term tamperproof should not be used to describe a package. See tamper evident.


A narrow strip of base material such as cloth, paper, plastic film, or other flexible composition coated on one side with an adhesive. The base material may be reinforced with fiber. The adhesive may be water-remoistenable, pressure-sensitive, or other formulation.

tape, pressure-sensitive

A pressure-sensitive adhesive applied to a thin supporting web. The tape may be wound around itself or with more aggressive adhesives may be attached to a release paper.

tape, strippable

A tape that is easily removed from the surface to which it is adhered.

tape, transfer-adhesive

A pressure-sensitive adhesive on a silicone-coated tape. When placed in contact with a substrate, the adhesive is transferred from the tape to the substrate.


The empty weight of a container or device that will hold an amount of product. Gross weight is the total weight of product and package. Gross weight minus tare weight is the weight of the product alone.


Those sensations that are developed on the mouth. The sensing cells on the tongue are able to detect only four tastes: sweet, sour, salty, and bitter. In addition to these, the mouth detects texture and chemical heat (for example, pepper). The sense of smell, on the other hand, is capable of differentiating thousands of aromas. Flavor, is a combination of the sense of taste and the sense of smell.

tearing bond

As adhesive or heat-seal bond that tears the paper or web substrate when the components are pulled apart.

tear propagation

The ability of plastic packaging films to continue to tear easily once the tear has been initiated. Some plastics, such as polyethylene, have no tendency to continue to propagate an initiated tear. Other plastics, for example oriented polypropylene, that is normally resistant to initial tearing, will readily propagate a tear once one has been initiated.

tear strength

The resistance of a material to tearing. The tear strength of paper and plastic films is often measured using an Elmendorf tear tester (see Elmendorf tear strength). Some other methods of measuring tear resistance are described in ASTM D 1004, D 922, D 1938, and D 2582.

tear strip

A feature incorporated into a package that allows for easier opening by a tearing action. Most typically, the tear strip is produced on paperboard packages by die-cutting a series of serrations into the board, but many other systems exist including die-cutting partway through the board, and the incorporation of tear tapes and filaments. The tear direction is best aligned to follow the board’s machine direction or grain. Tear strip features can be incorporated into packaging films by partly cutting through the film with a laser.

tear tab

A projection, adhesive-free allowance, or other device on a package that allows for easy gripping with the finger and subsequent pulling to create a tearing action on some part of the package. In most instances the tear tab will lead directly to a perforated tear strip, filament, or feature designed to conduct the tear along some predetermined path.


A trademark of Du Pont Co., Wilmington, Delaware, for its poly(tetrafluoroethylene), an inert polymer resistant to heat, solvents, and chemical attack. In the form of a film or an impregnator, used for its heat-resistant and nonsticking properties.


Transverse slipping of successive winds of a roll of material so that the edge is conical rather than flat. Typical causes are insufficient tension applied during winding, or a very low coefficient of friction. See roll, telescope.

temperature, ambient

The uncontrolled temperature of the immediate surroundings. Generally used to denote atmospheric temperatures within the range of normal room conditions.

temperature, application

The temperature at which a hot-melt adhesive should be applied.

temperature, brittle

A measure for judging a material’s relative flexing or impact performance at low temperature. For example the temperature at which a material will rupture by impact under specified conditions as per ASTM D 746.

temperature, deflection

The bending or deflection of a plastic specimen under a given load at an elevated temperature. ASTM D 648 describes a typical procedure for measuring deflection temperature.

temperature, glass transition

The temperature at which a plastic passes from a harder, stiffer phase to a softer, more rubbery or leathery state. Designated by Tg, it is usually determined by observing changes in the rate of physical change (for example, the rate of expansion) rather than a visible change of state. Tg is thought to occur at the point where the polymer chains exhibit segmental mobility. See also glass transition.

temperature, maximum-use

The maximum temperature to which a plastic material or other material can be exposed for an extended period of time without damage or distortion.

temperature, room

The prevailing inside temperature. Indefinite, but implies temperatures between 16 and 32oC (60 and 90oF). See temperature, ambient.

temperature, transformation

A temperature at which a phase change occurs.

temperature, transition

Generally, any temperature at which a polymer exhibits an abrupt change in phase or measurable property, or at which a property’s rate of change changes abruptly with temperature. The glass-transition temperature is the most commonly referred to transition.

tensile strength

A material’s resistance to extension or fracture when exposed to a force operating to extend, stretch, or pull it apart, at a specified temperature and at a specified rate of stretching. When the maximum stress occurs at the yield point, it is known as tensile strength at yield. When it occurs at break, it known as tensile strength at break, or ultimate tensile strength. The SI unit of tensile strength is the pascal (N/m2), but many US trade publications continue to use the pound (force) per square inch (psi). The ASTM tensile test for plastics is D 638.

tensile strength, ultimate

The tensile strength at which fracture occurs.


The stress caused by a force that is in the direction that will stretch or extend the material under tension.

tension control

A system incorporated into most web-fed machinery whose purpose is to control the web tension as it passes through the various operating stations from unwind to rewind.

tension decay

In plastic films or strapping, the loss of tension over time. Stress relaxation at constant strain.

tenter frame

A machine that continuously stretches a temperature- conditioned thermoplastic film in the cross direction (CD) to impart orientation. Clamps attached to endless chains grip the sheet on both edges and, while accelerating in the direction of sheet travel, also move outward from the longitudinal centerline, stretching the film to three of four times its original width. Combining a tentering frame with a machine direction orientation unit, produces biaxially oriented film.


The product of polymerizing three different monomers into one polymeric structure. For example, ABS polymer is produced from acrylonitrile, butadiene, and styrene monomers.


To perform a measurement of product attributes by a specified method. In its strictest sense, test implies a pass/fail criteria.

test conditions, standard

Atmospheric conditions of temperature and humidity in which laboratories agree to conduct tests, eliminating those variables in comparing results. The most common test condition for materials such as paper is 230C and 50% relative humidity. Standards for tropical, desert, frozen storage, refrigerated storage, and temperate high humidity can be found in ASTM D 4332.

temperature, use

The temperature at which a product will be used. The temperatures that a package will be exposed to during use are one of the considerations when selecting appropriate materials. For example, some plastics become brittle at freezer temperatures and would not be appropriate for freezer applications.

tensile properties

Properties determined by recording the stress-strain curve of a specimen as it is being pulled in tension. These include strength, elongation, and modulus of elasticity. (Reference method: ASTM D 882.)

test, abrasion-resistance

Determines the ability of a surface to withstand repeated scuffing or rubbing. The abrasion resistance of inks and printed materials is usually evaluated using a Sutherland rub tester (reference method ASTM D 5264). The resistance of stretch and shrink-wrap to abrasion is determined by simulating shipping vibrations (reference method ASTM D 5416). Similarly the abrasion resistance of applied labels, containers, and products packed as for shipment are determined by simulated shipping tests.

test, Elmendorf tear

A test for measuring the tear resistance of paper, paperboard, tape, and other flexible materials once the tear has been started by an intentional precut. The Elmendorf tear tester is used to measure the force required to tear a material. A calibrated pendulum swings by gravity through an arc, tearing the specimen from a precut slit, and the energy absorbed is recorded. Paper tear testing is described in ASTM D 689; plastic film in ASTM D 1922.

test, falling-dart impact

A test procedure in which a weighted dart is dropped on a film, sheet, or form to determine its resistance to puncture. There are a number of standard procedures, mostly varying in the method of determining the end point. For most procedures the impact dart mass is kept constant while the drop height is varied. The staircase method, (also up-and-down, or probit, method) provides a good estimate of the impact energy at which 50 percent of such samples may be expected to break. Groups of samples are tested at preselected drop height increments ranging from that at which most or all of the samples fail to that at which very few or none fail. An estimate of the standard deviation can be calculated from the data.

test, machinability

A test done to determine the machine processability of a material or package.

test, peel

A destructive method of examination that mechanically separates an adhesive or heat seal joint by peeling.

test, peel adhesion

The force required to remove a material adhered to another surface by a peeling action. Test protocols will typically specify a standard adherend surface, as well as the angle, speed, and atmospheric conditions for the test.

test, propagated tear

Materials such as papers and plastic films are frequently tested for their characteristic tear strengths. A propagated tear test refers to a test protocol where the sheet is first incised slightly to initiate the tear. In the instance of plastic films, a comparison of values for propagated and unpropagated tear strengths will provide information about the material’s notch sensitivity. See notch sensitivity and test, Elmendorf tear.

test, rub

A test to determine a material’s ability to withstand the effects of rubbing the surfaces together. See test, abrasion-resistance.

test, shear adhesion

A measure of the quality of an adhesive bond when subjected to a force in a direction parallel to the bond. The test value usually is stated as a force at failure. However, in some applications, pressure-sensitive adhesives, for example, the results may be stated as the time required to slide a specific size adhesive area over a standard testing surface.

test, slide angle

A test to determine the angle of incline that a package will slide against itself or some other predetermined surface material with the same characteristics. The test is performed by placing the test object on a plane that is slowly inclined until the test object begins to slide. The test value is primarily related to the static coefficient of friction.

test, smoothness

A method used to evaluate the degree of relief of a paper surface or that of other packaging materials.

test, stiffness

A method used to determine the degree of resistance per unit width that a paper, film, foil, or board offers to bending in the region of elastic deformation. This test is used to measure the capacity of a packaging material to be pushed through a machine, therefore, it sometimes is referred to as a machinability test. Representative tests are the Handle-O-Meter and Taber stiffness test. Measurements are usually taken in both the machine and the cross-machine direction of the material being tested.

test, tensile

A test to determine the resistance to rupture by tension. Usually reported in force per unit cross sectional area (pounds per square inch or pascals) or force per unit width (pounds force per inch or newtons per metre).


The measurement of material and object characteristics and values for the purposes of determining suitability for an application, verifying that an item meets specified requirements, or to determine (and resolve) failure mechanisms. The tests may be material characterizations or may be performance tests where an object or completed assembly is evaluated against a predetermined performance standard.

testing, accelerated

Laboratory performance test of a product, container, or system to evaluate its performance in a shorter time interval than that required under actual service conditions. Typical accelerated shelf life tests use elevated temperatures on the principle that elevated temperatures will accelerate any chemical reactions that are associated with aging or deterioration. A generally accepted guide is that a10oC temperature rise will approximately double chemical activity. Other acceleration protocols increase the severity or frequency of a particular hazard in order to simulate a real life condition over a shorter time period.

testing, performance

Most commonly used to describe the evaluation of a completed package. For example, a materials specification might call for a particular film thickness and specify seal width for a pouch. A performance specification would accept any film thickness or seal geometry providing the pouch could survive a one metre drop.


Referring to the use of heat in a process.

thermal conductivity

A measure of a material’s ability to conduct thermal or heat energy.


A material that changes color with temperature change. In packaging, thermochromic inks are useful as temperature indicators. In some formulations the color change is permanent and serves to indicate whether a product has exceeded set temperature limits. In other instances, thermochromic characteristics have been used to provide novel decorating effects for such products as chilled beverages or microwaveable foods.


A bimetallic device for measuring temperature by converting heat to a measurable electrical output.


Rubber-like elastic state of a normally rigid plastic resulting from an increase in temperature.


A method of forming plastics where a plastic sheet material is heated to a point where it is soft and pliable. The sheet is then formed to the desired shape using vacuum, pressure, mechanical assists, or any combination of these. Used to produce blisters, trays, platforms, cups, tubs, and other open containers and forms.


Any printing method that uses heat to create an image.


Describes a microorganism capable of tolerating and surviving elevated temperatures.


Any fully reacted polymeric material that can be repeatedly softened to a melt form and resolidified to a solid shape without significant change in properties. Structurally, thermoplastics are characterized by the absence of cross- linking between polymer chains. Most packaging polymers are thermoplastics.


See heat seal; weld.


A polymer that is typically made by a polymerization reaction that is not reversible and is characterized by a structure that

has a high degree of cross-linking between polymer chains. In most packaging applications, a thermoset starts as a prepolymer (the polymerization reaction is not complete) or as a mixture of reactive ingredients. The final polymerization takes place in the mold or use location.


Liquids, solvents, and/or diluents used to dilute or thin inks, adhesives and other coatings.

thinner, high-solvency

A volatile thinner that has high solvent power and thus is very effective in decreasing the viscosity of a coating solution.


A property of a fluid whose apparent viscosity decreases with time to a constant value at any constant shear rate. A thixotropic material gradually reverts to its original viscosity when the stirring stops. Thixotropy will be encountered in certain adhesives, greases, and paints. The opposite of dilatency.


Fluid droplets being thrown off an adhesive or coating applicator roll.

thumb cut

The cutout at the top of paper bags to facilitate opening. In paperboard cartons, a semicircular cutout at the top of a carton to facilitate removal of the contents.

tie coat

A coating layer whose purpose is to improve the adhesion of a following coating.

tie layer

A material that bonds two incompatible layers in a coextrusion.

tin foil

Frequently used to describe aluminum foil. The high cost of tin has eliminated tin foils from packaging applications, so the term is inappropriate.

tin tie

A paper or plastic wrapped strip of thin pliable metal attached to the top of a paper or plastic bag to provide a closure. Tin ties are convenient for reclosing bags when the entire contents are not used at one time, thus protecting the unused product from dirt and moisture. Also wire tie.

tinctorial strength

The power of a pigment or dye to impart color to an ink. See color strength.


Any shiny metallic or metal-coated material. Used in thin sheets, strips, threads, etc., to produce a glittering or sparkling appearance at small expense, often made by interweaving a textile or paper with metallic threads. Metallic tinsels are sometimes used on machinery to dissipate static electrical charges.


(a) A means of making a given color appear lighter in value by printing it on a white substrate in a dot or line pattern of less that 100% coverage in any given area. (b) A light value color produced by mixing white with the color. Compare to a tone where a darker color is produced by adding black (c) A printing defect in which emulsified lithographic ink appears in the nonimage area.


A general term for any type of lightweight paper product.

titanium dioxide

A white pigment made from titanium oxides and complexes. Titanium pigments have high opacity and brightening properties.


Permissible maximum and minimum deviation from the specified dimensions or qualities.

tonal curve

Used to smoothly adjust the overall tonal range of an image, or the individual tonal range of a single color channel.


Any final surface treatment on a material. Topcoats may be applied to impart aesthetic properties such as gloss, physical properties such as abrasion resistance, or chemical properties such as stain resistance.


Administration of a drug to the skin surface or the lining of body cavities. The therapeutic purpose is usually limited to localized areas.

total indicator runout

The deviation of a roll as read from the total movement of a dial indicator. It includes deviation because of roll eccentricity as well as deviation from a straight surface.


There is no single precise recognized definition of toughness. Toughness has been equated to resistance to abrasion, resistance to penetration by sharp objects, and lack of brittleness. Toughness generally implies having very substantial elongation to break accompanied by high tensile strength. One proposed definition is the energy per unit volume to break a material, equal to the area under the stress- strain curve. In packaging, nylon film is considered to be a tough film.


The degree to which a toxic or poisonous substance affects living organisms. Toxic substances used in the workplace must be described on Material Safety Data Sheets (MSDS) Strict laws govern the packaging and shipment of toxic materials.


A noxious or poisonous substance formed during the growth of certain microorganisms.


Trade name for a polymethylpentene polymer from ICI Americas, Inc., Wilmington, DE. See polymethylpentene.


(a) In calibrating, the ability to trace the calibration of measuring equipment to the national standard or a recognized primary standard. (b) In relation to data, the ability to trace the operational, computational, and recording steps of a measurement or evaluation of an item, process, or service. (c) In distribution, the ability to trace the history, application, or location of an item and like items or activities by means of recorded identification.


The manner in which a web travels through a web-fed machine such as a printer or coater-laminator.

trade name

A name or term that is owned by registration of a copyright that identifies the product or service of a company.

A color made darker than the original by adding a complementary color or black. A pure color can be tinted by adding white or toned by adding black.


(a) A dispersion of highly concentrated pigment or dye used to manufacture, strengthen, or modify the color of an ink or to modify the color of a plastic. (b) The colorant in electrostatic imaging.


Refers to molds, dies, jigs, and fixtures that are required above and beyond the base manufacturing machine, which will be producing a product. In most instances, tooling is the customized part that fits into a stock machine to produce a given product.

tooling cost

The one-time cost of manufacturing tooling such as molds, cutting dies, fixtures, and so on that may be required for a proposed package.

trade term

Any word or phrase used within a trade or industry, generally having a meaning more specific or at variance with common or dictionary usage.


A distinctive name, symbol, or figure adopted by a manufacturer or other firm to identify the company and/or its products.


A momentary, nonpersisting condition or event.


Describes a material or substance capable of diffusing light. Some light will be transmitted, but not enough to produce a clear image.


A photographic positive on a clear or transparent support. Commonly, the term is applied to full-color transparencies such as Kodachrome.


A material or substance that has a high degree of light transmission; i.e., clear enough to see through.

trap, trapping

(a) In printing, inks may be overlapped slightly to ensure that no substrate shows through within the register variations of the printing press. (b) Wet trapping is the ability of one ink to adhere to a previously applied and still wet ink. Dry trapping is the ability of an ink to transfer to a dry surface.

treatment, corona

A treatment to alter the surface of plastic and other materials to make them more receptive to adhesives or printing inks. An electrical discharge creates ozone, which in turn oxidizes the substrate surface and creates polar sites that contribute to strong bond formation.

substances and solvents but poor barriers to nonpolar solvents, gases, and flavors. The polyolefin barrier quality can be raised by various surface treatments that react with the polymer surface. One such treatment is the exposure of blow-molded polyethylene bottles to a gaseous mixture of fluorine and nitrogen. The highly reactive fluorine attacks the polymer surface, providing some cross-linking and creating a thin fluoroplastic layer on the contacted areas, substantially improving barrier qualities.

trial-size package

A small package typically holding one application of the product, or enough for the recipient to form a judgment as to its nature. Usually given away as a promotion or product introduction.

triboelectric charging

The electrostatic charges generated when two pieces of material that have been in intimate contact are separated. See static and triboelectric series.

triboelectric series

Two non-conducting substances in contact are capable of developing and holding a static electrical charge. The magnitude and polarity of the charge will depend on the materials concerned. Materials can be arranged in the order and tendency to develop and hold static electrical charges. A partial list of the triboelectric series is provided below. The magnitude of the charge generated is a function of their relative separation in the table. The more positive of the two materials will become positively charged.

treatment, dry-end

In papermaking, any treatment, such as clay coating, that is applied after the paper is formed and partly or completely dried.

treatment, flame

A treatment that involves exposing a material or object (such as a plastic bottle) to a gas flame to increase the polarity of the surface. The amount of flame treatment depends on the condition and position of the flame and the time of exposure. See also treatment, corona and flame, oxidizing.


(a) (noun) Excess material that has been cut away. (b) (verb)To cut away excess or imperfect material, such as uneven edges, sheet not removed in blanking operations and so on. (c) (noun) decorative components applied to an otherwise complete package. (d) (verb) To apply trim.

trim mark

In printing, marks placed on copy to indicate the edge at which it will be cut. See crop mark.

trim size

(a) The maximum width that can be produced efficiently on a converting machines, minus allowance for edge (deckle) trimming. (b) The size of something after trimming.


(a) A continuous web form made by sealing the edges together. (b) The hollow cylinder on a form-fill-seal machine around which the web is wrapped and sealed to form a continuous sleeve. Product is introduced through the tube and the tube ends sealed and cut off at appropriate points to form a sealed package.

tubing, seamless

A continuous tube of plastic tubing produced by the blown film method, characterized by not having any longitudinal seal. Seamless tubing is typically used to make plastic bags.


(a) The folds that comprise the sidewalls of square and automatic-type bags, which are folded (tucked) in to permit the bag to be packed flat. (b) The end portions of the top or bottom flaps of a folding paper box (carton), which are inserted inside the container to hold the end (top or bottom) flaps in place.

tunnel, drying

The compartment through which the web passes for final drying after printing. Normally drying is accomplished with a flow of heated air.


A laminating defect caused by incomplete bonding of the substrates. Tunneling is characterized by release of narrow longitudinal portions of the substrates into long tunnel-like shapes.

turret winder

A winder with two positions located at the opposing ends of a centrally mount arm that can be rotated and indexed.

turning bars

Stationary bars on a web press arranged to turn the web over so that the bottom becomes the top in order that it can be printed on both sides in one pass.

twist tie

See wire tie and tin tie.

twist wrapping

A method of wrapping commonly used on confections where the wrapping material is formed into a tube around the item and the ends then closed by twisting. The wrapping material must have good deadfold properties otherwise it would unwind.


When used in reference to an adhesive or coating, a material which is supplied in two separate parts. Mixing the parts initiates a chemical reaction, which will eventually set or solidify the material. Two-component adhesives and coatings will have a pot life, after which the material can no longer be used.

two-dimensional code

See bar code, stacked.

type, body

The bulk copy used for reading matter as opposed to headings or display.

type, boldface

Heavy type, in contrast to regular or light face type.

type, condensed

A font that has proportionally narrower typefaces.


The style, arrangement, or appearance of typeset matter. The art of selecting and arranging type faces.


Du Pont Co., Wilmington, Delaware, trade name for a sheet product made by pressing together very fine extruded filaments of polyolefin polymer. Tyvek is similar to paper in appearance and feel, however, because of its polymer nature, it is waterproof and exceptionally strong. Tyvek is used for envelopes and bags where exceptional strength or water resistance is important. Tyvek materials will not produce fine cellulose dust or fibers. This quality makes it a candidate for packaging applications, such as medical device packaging, where a paper-like material, but without the possibility of liberating free fibers, is required. Since it is porous, Tyvek packages and contents can be sterilized using gas sterilization techniques.


See Uniform Classification Committee and Uniform Code Council.


A standard international machine-readable code that allows a maximum amount of scannable information (for example, expiry date, lot number, origin, and so on). EAN requires an ANSI grade C or better read. This cannot be achieved on natural kraft, and corrugated washboarding further aggravates the problem. Accordingly, EAN 128 is most usually applied as a label to shipping containers.


See under color removal.

U film

A plastic film folded over exactly half the film’s width. the film is referred to as U film. A film with a portion of its width continuously folded in along one edge is a J-film. If the fold is gusseted along the folded edge it is a W film.

ultrasonic frequency

A sound frequency approximately 18 kilohertz or higher and above the limit of human hearing. Most ultrasonic devices operate well above this level.

ultraviolet (UV)

A region of the electromagnetic spectrum just shorter in wavelength than the visible portion, with wavelengths between 0.01 and 0.4 micrometre. High intensity mercury vapor tubes emit light in the 0.315 to 0.400 micrometre range, but the most common source of UV radiation is in sunlight. UV radiation has enough energy to initiate chemical reactions and degradations that would not normally take place at ambient conditions. The energy of UV radiation is put to good use in the various photopolymer and photochemical preparations used in the production of printing plates.

ultraviolet curing

The curing of certain polymers, inks or coatings with ultraviolet light (UV). The material to be cured usually incorporates a photoinitiator that activates the curing process when stimulated by UV energy sources. Typical UV-cured systems are 100% solids content and cure very rapidly, offering significant production advantages.

ultraviolet stabilizer

An additive that protects against ultraviolet (UV) degradation. An additive that preferentially absorbs UV radiation and dissipates the associated energy is sometimes called an UV absorber or UV screening agent. Additives that do not actually absorb UV radiation, but protect the polymer in some other manner are called UV stabilizers.

ultraviolet varnish, ink

See ink, ultraviolet.


A coating that was not baked long enough or at a high enough temperature to develop its optimum properties.

under color removal (UCR)

The reduction of yellow, magenta, and cyan dot percentages in gray and black areas of a separation. Black ink is then printed in the place of the deleted inks. The dark area is now printed using one ink rather than a combination of inks, thus reducing ink usage, producing a blacker and darker image if required, and reducing problems associated with heavy ink laydowns and trapping.


A degree of curing that is less than optimal. Undercured materials do not achieve their full potential in chemical and physical properties.


An indentation, extension or protrusion on a plastic part that impedes withdrawal from the mold. A molded shape that requires mold parts that are able to be moved out of the way to release the part. Undercuts significantly increase tooling cost.


The first color impression in printing, where there will be a second color application over the first. Usually a color is underprinted to attain the true ink color by printing the same or darker value of the same hue, or even black, to absorb the light reflected from the paper through the ink applied in the second impression of the design. For example, a single impression of dark blue printed on white paper may lack “depth” due to some light being reflected through the ink film by the white paper. If, however, the design is first underprinted in black or dark blue, and then printed with the final color, the latter will show the desired “depth” and hue.


The amount of produced product short of the required amount.


See poor trapping.

Uniform Code Council (UCC)

The North American body, based in Dayton, Ohio, that controls the Universal Product Code (UPC) and other machine-readable code symbologies.

unit-dose package

A single containment package that holds one discrete item of usage. A complete unit-dose package may hold a number of discrete items of usage but each unit of use must be released individually from the package, generally in a non-reclosable or resealable manner. A major application is for the delivery of pharmaceutical tablets.


Packages assembled into a stable load for safe storage and transport.

unsaturated compounds

Any compound having more than one bond between constituent atoms such as a double bond between two carbon atoms. Other atoms can be added at that point, eliminating the double bond and creating a new compound. Simple unsaturated compounds are the basic building block of most polymers.


A flexible material that is not laminated to another substrate that would give it mechanical support. Used most frequently to describe aluminum foil that is not bonded to another material or substrate.

unwind stand

In a web-fed process such as printing or film laminating, a stand or a driven machine holding a roll of the substrate to be printed or laminated and supplying the web to the coating equipment at the rate and tension required.


In printing, the number preceding “up” indicates the number of complete images on one press sheet or on web fed presses the number of images printed for each revolution of the printing cylinder. One-up means that the plate prints one image for each revolution, two-up means two, and so on. Also applies to operations such as die-cutting.


See Universal Product Code.


A two-part machine-readable Universal Product Code (UPC) used for individual items or SKUs sold to consumers. This code can be used on the shipping container if the product packaging is also the shipping container. It can be run 200% of size. UPC-A should meet the retail scanning guidelines of ANSI grade C.

UPC aspect ratio

The ratio of the height to the width of a Universal Product Code (UPC) symbol.

UPC bar

symbol that together with the spaces between them make a machine-readable code.

UPC bar-width reduction

Compensation for press printing gain by the uniform reduction in the width of each bar of a Universal Product Code (UPC) film or digital master.

UPC character, machine-readable

The combination of two dark bars and two light spaces within the seven modules of a Universal Product Code (UPC) character, which a scanner interprets as a number.

UPC magnification factor

The ratio of the Universal Product Code (UPC) symbol width to the recommended nominal width. A magnification factor less than 1.00 results in a symbol smaller than a nominal-size symbol; a magnification factor greater than1.00 results larger than a nominal-size symbol.

UPC module check character

A calculated number based on the company and SKU numbers, encoded at the end of a Universal Product Code (UPC) symbol that is used by scanners for error detection.

UPC number system character

A number encoded in a Universal Product Code (UPC) symbol, which is used to identify different number systems. The human-readable number system character is located in the left-hand light margin area.

UPC space

The light areas between bars of a Universal Product Code (UPC) symbol.

UPC truncation

The practice of decreasing the bar height of a Universal Product Code (UPC) symbol, that results in the reduction of the aspect ratio of that symbol from the aspect ratio of the nominal-size version of that symbol.

UPC zero-suppression symbol

A Universal Product Code (UPC) symbol where some of the zeros in the product number have been dropped out resulting in a readable code that has fewer than the nominal ten digits. Zero suppression is a way of reducing code size for applications where space is limited.


A polymeric material made by the reaction of any of a group of isocyanates with any of a group of multifunctional glycols. Depending on the participating monomers, urethanes can be made with a wide range of properties (for example, thermoplastic, thermoset, rigid, elastic, cellular, and so on). See polyurethane.


Acronym for U.S. Department of Agriculture.


Testing the components of an operation to confirm that they are performing the function they are supposed to perform.


Vapor in most contexts refers to a substance that, although present in the gaseous phase, is normally a stable liquid or solid at ambient temperatures. Gas, on the other hand, is used for substances that do not have stable liquid or solid states at ambient conditions. Water can be in a vapor state but oxygen and nitrogen are gases. In general packaging usage, vapor is taken to mean water vapor.

vapor barrier

A layer of material through which an unspecified vapor will pass only slowly, or not at all. A full definition of vapor barrier would need to identify the vapor to which the material acts as a barrier. See vapor.

vapor pressure

The pressure exerted by the gaseous form, or vapor, of liquid. When the pressure above a liquid is below its vapor pressure, boiling occurs. If the pressure at any point in the flow of a liquid in a pipe falls below the vapor pressure, the liquid flashes (cavitation) into vapor.

vapor transmission

The properties of a packaging material permitting the passage of vapor. In general packaging usage, vapor is taken to mean water vapor.


(a) A protective coating applied to a printed sheet for protection and appearance. They must be pale in color, hard drying, scuff-resistant and glossy, both on the unprinted and printed areas. Varnishes may be solvent based or water based and solidified by drying, oxidation, or curing by ultra violet radiation. (b) The binder component of an ink.

vacuum forming

A type of thermoforming where a vacuum is used to pull the pliable heated film or sheet into close conformity to a mold shape.

varnish, overprint

Broadly, transparent coatings applied for the purpose of protection or the enhancement of the visual appeal of a printed surface. See varnish.

varnish, spot

Varnish that has been selectively applied while the sheet or web being printed is on the press. Accomplished by using a printing plate as the applicator, it is considered a “color” by printers. Spot varnishes are most typically used to create local glossy areas for visual appeal.


See volatile corrosion inhibitor.


See vinyl chloride monomer.


The liquid portion of a printing ink that carries the pigment and other portions of the ink to the substrate surface. See ink vehicle.


See form-fill-seal, vertical.

vicat softening point

A method of quantifying a material’s point of softness when heated. Specifically the temperature at which a flat-ended needle of 1 square millimetre cross section will penetrate a thermoplastic material 1 millimetre under a given load. (Reference method ASTM D 1525.)


An illustration where a color fades gradually away until it blends into the unprinted substrate. For example, a portion of artwork where the color goes from solid (100%) to below 10% ink coverage over a distance.


In common usage a generic term for poly(vinyl chloride) or for film or other products made from it. (b) More broadly the term can be used to describe any polymer made from a vinyl monomer, except those specifically covered by other classifications such as acrylic and styrene plastics. Other vinyl plastics are poly(vinyl acetate), poly(vinyl alcohol), and poly(vinylidene chloride).

vinyl chloride monomer (VCM)

The monomer from which poly(vinyl chloride) (PVC) is produced. VCM a potential carcinogen, and so VCM levels are constantly monitored to ensure that all VCM has been polymerized to poly(vinyl chloride).

virgin material

Any material that has not been previously used or processed other than that required for its original manufacture.


A material’s behavior is classed as elastic if after deformation due to an applied stress the material returns to its original size (providing the material’s yield point has not been exceeded). A material that flows and deforms permanently when under stress is said to exhibit viscous flow. A material that exhibits elements of both behaviors is be viscoelastic. Elastic behavior is time independent, while viscous flow is time dependent. A plastic that is quickly bent and released will exhibit primarily elastic behavior. The same plastic bent (stressed) to a new shape and held there for a period of time will become permanently deformed.


A qualitative term denoting that the material to which it is applied is “thick” and flows sluggishly, rather than being “thin” and flowing freely. The transition region between “free-flowing” and “viscous” is subjective but generally would apply to fluids slightly more viscous than water.

visible light

Light that can be seen by the eye. Having wavelengths between 0.4 and 0.75 micrometres.


See volatile organic compound.


An emptiness or absence of material. A location not occupied by product as for example, a lack of coating or adhesive.


Said of a material subject to rapid evaporation and that easily passes from a liquid to a gaseous state under ambient conditions. A material having a high vapor pressure at room temperature.

volatile corrosion inhibitor (VCI)

A material applied to packaging materials that gives off a vapor that will inhibit corrosion of a part sealed in a package made of that material.

volatile organic compound (VOC)

Any organic substance that can be evaporated at ambient or process conditions. In packaging these come primarily from solvents used for preparing inks, adhesives and coatings, as well as from various solvent-based cleaning agents. The atmosphere release of VOCs can pose serious health and environmental hazards and is restricted by law. There is a trend toward reducing the use of VOCs or, if required in an operation, toward eliminating the discharge of released vapors into the atmosphere.

volatiles content

The percent by weight of volatile material that will be lost from an adhesive or ink during drying. The remaining non- volatile material is the solids, or nonvolatile, content.


The tendency to evaporate under normal atmospheric conditions. This phenomenon is closely related to vapor pressure. The relative volatility of two liquids at any temperature is the ratio of their vapor pressures at that temperature.


Instrument used to measure the viscosity of an adhesive, ink, varnish, or other liquid. Many types of instrument exist for determining viscosity and care should be taken to ensure that identical instruments and conditions were used when comparing viscosities. The Brookfield, the most common viscometer use for measuring adhesive viscosity, determines the rotational resistance to turning a series of spindles and cylinders immersed in the adhesive.


A measure of a fluid’s resistance to flow. Water would be classed as a low-viscosity fluid, while a syrup would have a high viscosity. Viscosity is measured in centipoise or pascal/ seconds.

viscosity controlling agent

Substances added to increase or decrease viscosity of a product.

viscosity, absolute

Absolute viscosity or the coefficient of absolute viscosity is a measure of the internal resistance to movement. In the centimetre, gram, second (cgs), or metric system, the unit of absolute viscosity is the poise.

viscosity, apparent

Viscosity of a complex (non-Newtonian) fluid under given conditions. See viscosity.

viscosity, kinematic

The ratio of the absolute viscosity to the mass density. In the metric system, kinematic viscosity is measured in stokes or square centimetre per second.

viscosity, specific

The ratio of viscosity of a fluid to that of a standard fluid (usually water, or the solvent in the case of solvents), both viscosities being compared at the same temperature. See viscosity.


An undesirable change in shape due to differential shrinkage or expansion rates, or other factors that affect a material’s or product’s geometry. Usually expressed as a measure related to the ideal part. For example, the degree of difference from flat, applied to warped board as compared with flat board, or the dimensional distortion in a plastic part after molding.


Components, materials, or packages that are of unacceptable quality.


(a) The loss of materials occurring in the process of manufacture. (b) Material trimmed and salvaged in a processing operation. See scrap.

water-vapor transmission rate (WVTR)

A measure of the rate that water vapor passes through a film, sheet or dimensional part. Transmission rates have been expressed in a variety of inch/pound, metric and mixed units and care should be taken to ensure the same units are being used in any comparisons. Water-vapor transmission rate terminology is preferred to moisture vapor transmission rate. (Reference test methods: ASTM D 895, D 1251, D 3079, D 3199, D 4279, and E 96.)

water absorption

The percentage of water absorbed by a material in a given time. (Reference methods: ASTM D 570, and TAPPI T441.)


A solid, somewhat greasy, plastic when warm, liquid when hot, with melting points Typically between 50 and 70oC (120 and 160oF). Paraffin waxes most commonly used in packaging are refined from petrochemical sources, although waxy substances may also be of plant or animal, origin. Used in adhesive formulations either alone as a low strength adhesive or part of hot-melt adhesive formulations and as coatings to provide waterproofness, reduced coefficient of friction, anti- blocking qualities and surface lubricantation. See paraffin.

wax, microcrystalline

A high molecular weight petroleum wax characterized by minute crystals and distinguished by its solid, wax-like appearance at room temperature. Most commercial microcrystalline waxes have melting points between 60 and 93oC (140 to 200oF). Used for laminating and surface coating in preference to less ductile and more brittle paraffin wax.

wax pick

The ability of a paper surface to resist the adhesive strength of a graded set off formulated waxes, where higher numbers indicate a higher surface strength. With plain papers, the procedure gauges the internal bond strength of the cellulose fibers. With clay-coated papers, the procedure gauges the quality of the clay bond to the paper.

weathering resistance

Ability of a material to retain its original physical properties and appearance under prolonged exposure to outdoor weather. Also called weather resistance.


Laboratory device for subjecting coatings to ultraviolet light and a water spray.


Paper, film, foil, or other flexible material that is unwound from a roll and passed through a machine.

web bag

A condition where the center of a web sags or droops while the edge remain tight. Opposite of web sag.

web direction

The direction that the web travels through a machine. Same as machine direction.

web drying systems

Any system that removes volatile materials such as organic solvents or water from a printed, coated or adhesive laminated stock. Most typically this is done by passing the stock through a forced-air-flow tunnel or chamber. Some paper stocks are dried by passing around heated rolls accompanied by forced air.

web elongation

The elongation of a web from local or overall tension as it is being passed from the unwind to the rewind of a converting machine. Web elongation will affect print registration.

A measurement expressed as a decimal, that indicates the ratio of the water vapor pressure of a food or other product to the water vapor pressure of pure water under the same conditions. Aw indicates the relative humidity at which a food or other substance will neither gain nor lose moisture. A product with an Aw of 0.30 would neither gain nor lose moisture at a relative humidity of 30% (the equilibrium relative humidity). Since typical relative humidity is most commonly higher than 30%, such a product would have a tendency to gain moisture under most ambient relative humidity conditions. A suitable moisture-barrier package would likely be required.

water resistance, water resistant

The material property that resists uptake or passage of water. The resistance of a packaging material to deterioration or change when in contact with water. To be water resistant is not to be waterproof.


The material property that allows it to be in direct contact with water for extended periods without significant change in properties.

web guide

A mechanical device that keeps the web traveling in a true, straight line through a press.

web sag

A condition where the edges of a web sag or droop while the center remains tight. Opposite of web bag.

web tension

The amount of pull or tension applied in the direction of travel of a web by the action of pulling the web through the press.


A condition where dried thread-like adhesive filaments are formed during application. Also referred to as spider webbing, cottoning and feathering.

wet bond, wet bonding

To laminate two substrates by the application of a water or solvent borne adhesive between them and drying away the carrier solvent or water. Wet bonding requires that at least one of the substrates be porous to allow the escape of water or solvent vapors.

wet mil

The thickness of an adhesive or coating in the wet state as applied to a surface.

wet out

To form a molecular attraction to a substrate. The ability of applied fluids such as adhesive, ink or coating to form a chemical bond with a substrate depends on the fluids compatibility with the substrate. The applied fluid molecules must have at least as much attraction for the substrate molecules as for other fluid molecules. Where this happens, the fluid will flow out over the substrate in an even film, and the fluid is said to wet out the substrate. Where fluid molecules have greater attraction to themselves than for the substrate, the fluid will bead up into droplets and not wet out the substrate surface.

wet pick

Resistance of wet or dampened paper to picking, particularly as applied to printing.

wet strength

A measure of the physical strength properties of paper, adhesive bonds, or some other material or assembly when saturated with water, usually expressed as wet tensile strength, wet bursting strength, and so on.


The ability of a substrate surface to attract liquid adhesives, coatings, or inks, through molecular attractions. The attraction is dependent on the substrate and the adherend polarities. The degree of wettability is measured by the contact angle of a drop of liquid on the intended substrate, or by measuring the surface tension of the substrate (reported in dynes). See wet out.


The ability of an adhesive, ink or coating to make contact and spread evenly over a substrate. Proper wetting is a function of the surface energy of the adhesive and the substrate. The adhesive must have attraction to the substrate at the molecular level for proper wetting to occur. See wet out.

wetting agent

Chemical agent used to overcome reluctance of dissimilar materials, one of which is a liquid, to wet or mix, by reduction of the surface tension of the liquid. See surfactant.


A buildup of coating residue on the downstream side of a coating blade, usually the result of a partly dried coating extruding under the blade.


A color composed of approximately equal amounts of the wavelengths in the visible spectrum.


The placement of completed bags onto a fixture that will assemble stacks or bundles of the required count and present them to the next step in the operation.


In printing, a too rapid ink absorption into a substrate, causing excessive strike-through, smudged detail, and fuzzy lines.

wicking, edge

The movement of a fluid such as oil or water through an uncoated or cut edge of a packaging material.


The dimension across the web, more commonly expressed as cross direction or CD. Also described as transverse direction.


Generally, any device for winding paper, plastic or other material into coils or rolls.


A transparent opening in a package allowing for viewing of the contents.

wire tie

A bag closure device made from a wire enclosed in a paper or plastic sheath. The wire is wrapped around the gathered bag opening and twisted around itself to make the seal. See also tin tie.


Small crease or fold in a smooth surface.


wrong reading

Visual orientation of an image so that it reads right to left (a mirror image). A wrong reading flexographic plate will produce a right reading printed image when pressed against a substrate.


See water vapor transmission rate.

work in progress (WIP)

A term for product that requires further work for its completion.

working life

The period of time during which an adhesive remains suitable for application before hardening in the receptacle. See pot life.

wrap, wrapper

(a) A sheet of flexible material used for wrapping product. (b) A machine that performs a wrapping function. (c) See arc of contact. See also stretch wrapper.

wrap, decorative

A wrap whose principal use is to enhance the appearance of a package, as contrasted to a functional wrap, which is used primarily for protection or handling convenience.

wrapper, heat-seal

A sheet of flexible material that has been coated on one or both sizes with a heat sealable medium, that will cause the material to adhere to itself after being heated to the fusing temperature of the coating.


The amount of product that can be produced from a given weight of material. Most packaging raw materials are sold by weight. However, because of density differences, the same weight of similar materials can produce different amounts of finished product. For example, yield for a plastic resin used for film manufacture might be expressed as the number square metres of film that could be made from 1 kilogram of the material (square inches per pound.) In other instances, yield might be expressed in terms of volume per unit weight, or the actual number of physical objects per unit weight.

yield point

In tensile testing, the first point on the stress-strain curve at which an increase in strain occurs without an increase in stress. This is the point at which permanent (plastic) deformation of the specimen begins. Many plastics do not exhibit an identifiable yield point.

Young’s modulus of elasticity

A term associated with tensile tests, it is the ratio of the amount of stress to the amount of strain (initial slope of a stress-strain curve).

Zahn cup

An instrument for measuring the viscosity of flexographic inks. The device consists of a cylindrical cup with a rounded bottom suspended on a wire handle. Zahn cups come in sets of five, with each one having a different diameter orifice in its rounded base. The cup is dipped into the ink and the time required to run out of the orifice is noted.

zig-zag fold

See fanfold.


See zip-lock.


A plastic bag with an incorporated zipper device, which can be readily opened by pulling the two sides of the bag apart and resealed by pressing the mating halves of the zipper together and running the fingers down its length. Ziploc is a registered trade name for such a system.