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ACCELERATED AGING
A means of subjecting materials to special environmental conditions for a relatively short period to predict the course of ambient condition aging.
ACCUMULATOR
That section of a continuous web operation in which the web material (paper, films, etc.) can be stored for subsequent use during a change operation, splicing, etc., without interruption of the process.
ACETATE (Cellulose Acetate)
A thermoplastic polymer which is the reaction product of acetic anhydrideoracetal chloride and the solubilized portion of cellulose. The resulting product can be cast into a transparent film possessing both the low elongation and moisture content typical of paper.
ADHESION, SPECIFIC
A bond between surfaces resulting from either chemical bonding or other molecular interactions (hydrogen bonding, dipole interaction. dispersion forces).
ADHESIVE BLEED
See Cold Flow.
ADHESIVE RESIDUE
That portion of the adhesive which remains on the bonded surface when a pressure-sensitive label or tape is removed.
ADHESIVE TRANSFER
The result of an adhesive having a greater affinity for the second surface to which it was bonded rather than the primary substrate.
AGGRESSIVENESS, ADHESIVE
See Tack.
AGING
See Accelerated Aging.
AIR KNIFE COATING
A method to distribute and meter a liquid coating by a controlled stream of air.
ALLIGATORING
Term describing the action of a lacquer film when it cracks into large segments, resembling the hide of an alligator. When fine and incomplete, it is usually referred to as “crazing.”
AMBIENT CONDITIONS
The temperature, humidity, and other factors defining some long-term surrounding environment.
ANCHORAGE
The adhesion of a pressure-sensitive adhesive to the surface to which it was originally applied (as opposed to adhesive transfer).
ANCHORED COATING
A coating applied to a base sheet (usually bonded) so that it very strongly resists separation.
ANGEL’S HAIR
Fiber-like strands of material pulled away from a thermoplastic film during heat sealing and cutting operations employing hot knives or wires.
ANGSTROM
A unit of length equal to 1 x 10-8 centimeters. Commonly used as a measure of thickness of vacuum-deposited metals.
ANNEALING
Technique of keeping a material for a period of time at a temperature short of melting, to relieve internal stresses; the application of heat to a formed or oriented plastic article to relieve stress resulting from the forming or orientation process.
ANTI-BLOCK
The name for a treatment applied to plastic film surfaces to keep them from sticking together or “blocking” when they are tightly rolled up on a mandrel.
ANTI-FOG
A property of polymer films designed to prevent the formation of water droplets or condensation on the film surface. This is particularly important in applications where maintaining visibility is crucial, such as packaging for refrigerated or frozen products. Anti-fog films help to ensure that the packaged items remain visible, and the packaging material does not obstruct the view due to fogging.
ANTI-SKID
Refers to a property of polymer films designed to reduce slippage between stacked layers of film or between the film and a surface. This property is particularly important in applications where the film is used in layers or in situations where preventing sliding is crucial.
ANTIOXIDANT
A substance that slows the oxidation rate of a material.
ANTISTATIC AGENTS
Chemical substances which increase the surface conductivity of plastic materials, thus preventing a buildup of electrostatic charges.
ANVIL ROLL
A hardened steel roller placed opposite a scoring or rotary knife on a slitter or die-cutting machine.
ARC RESISTANCE
A measure of an electrical insulating material’s resistance to a breakthrough by an electric current.
ARROWHEADS
Fine “checkmark” scratches which randomly occur across a film in discrete longitudinal bands or repeating patches.
ASEPTIC
Free from septic matter or disease-producing bacteria. In food processing and packaging, this is an adjective that describes the system used to package food in a sterile fashion.
ASH CONTENT
The solid residue remaining after a substance has been incinerated to a point where all combustible components are driven off.
AUTO IGNITION POINT
The temperature at which mixtures of solvent vapor and air will ignite without the aid of a spark or flame.

 

BACK PRESSURE
The pressure produced at the exit sideof a pump. In an extrusion process, the resistance to forward flow of the molten material.
BACKGROUND SCRATCHES
Marks on a metallized material, the source of which is in the metal deposition.
BACKING
The substrate to which an adhesive coating is applied.
BACKSIDE TREATMENT
Inadvertent treatment on the opposite side of a film being corona treated, often caused by rippling or wrinkles in the film as it passes through the treater.
BAG, CRIMP-BOTTOM
A flat bag with a crimp-seal bottom (no fold-over), usually heat-sealed using serrated dies. Not a particularly strong type of bag (see: Flat Bag).
BAG, DUPLEX
A bag constructed of two plies of material, generally spot-sealed to each other, especially at the mouth.
BAG, FLAT
Simplest form. A web of material folded into a flat tube with side or center seam, then cut off and sealed at one end. Has only two dimensions: length and flat width. Flat bags may have a crimped seal or a fold-over seal, in which a short section is turned back and sealed in place by heat, adhesives or a combination of both.
BAG, GUSSETED
Bag having bellows-like folds on each side that expand outward when bag is filled.
BAGGINESS
The sag of a web in the transverse direction when a length of film is stretched in both the transverse and machine directions.
BAGGY EDGES
See Web Bag.
BAKING
The process of curing or drying an adhesive or coating by the application of heat.
BANANA ROLL
See Bowed Roll.
BAND
A dark-colored circumferential ring in a slit roll caused by a slightly heavier moisture content or slight variations in a base sheet thickness.
BANDS, BAGGY
A defect in a roll; a slack lane or a baggy section, which shows up when film is unwound and pulled taut.
BARRIER COAT
A coating applied to a material to prevent migration of some substance into or through the material.
BASE SHEET
A sheet to which coatings, inks, lacquers, etc. are applied; fundamental component or “starting point.”
BASIS WEIGHT
A method for calculating the weight of a paper structure, usually reported as pounds per 3000 square feet.
BEACH TEST
A puncture test for determining the strength of facing materials.
BEAD
A thickened section at the edge of a roll of film. Also see High Edges.
BELLED EDGES
Raised edge normally caused by poor slitting techniques.
BELLY
A fullness in cross section of the web, either in the center or near the sides.
BETA-RAY GAUGE
Consists of two facing elements, one emitting and one detecting beta radiation. The device accurately measures density or thickness when mounted above and below the web.
BIAXIAL ORIENTATION (BIAX)
The process of stretching a plastic film (usually at elevated temperature) in both the machine and transverse directions to improve tensile, modulus, and elongation properties in both directions.
BIAXIALLY ORIENTED POLYETHYLENE TEREPHTHALATE (BOPET)
Commonly known as polyester films, possess several characteristics that make them suitable for a variety of applications; High Tensile Strength, Chemical REsistance, Dimensional Stability, Transparancey, Clairty, Barrier Properties, Low Moisture Absorption, High Temperature REsistance, Printability, Flexibiliity, Recyclability.
BINGHAM ROLLER
See Flex Spread Roller.
BIODEGRADATION
The degradation of a material by living organisms, such as bacteria, fungi, or yeasts.
BIREFRINGENT (Double Refraction)
The property of a film to take a uniaxially oriented polarized beam of light and transform it to biaxially oriented light via a double refraction.
BLANKING
The cutting of flat sheet stock to shape by striking it with a punch while it is supported on a mating die. Also see Die Cutting.
BLEED (or Bleeding)
To run, diffuse, or migrate colors into unwanted areas adjacent to printed areas. The migration of plasticizers from an adhesive film into the substrate or vice versa.
BLISTER PACK
Package formed from semi-rigid thermoplastic material so that the sheet forms a transparent dome over the package item.
BLISTERING
A surface irregularity in an adhesive or coated film consisting of a small gas or liquid pocket between the film and base surface. May be caused by insufficient adhesive, inadequate curing, entrapped air (or water or solvent), or improper cleaning of the surface. Can also occur in an uncoated film.
BLOCK, BLOCKING
Undesired adhesion “sticking together” of two or more plies of material in roll or sheet form. May be caused by exposure to excessive heat, pressure, or humidity; in printed film, occasionally by improper or insufficient drying of inks, resulting in sticking together of printed areas.
BLOOM
A cloudy effect or whitish powdery deposit on the surface of a material caused by the exudation or migration of a compounding ingredient such as a lubricant, stabilizer, pigment, plasticizer, etc.
BLOWN FILM
A continuous tube produced by extruding thermoplastic film through a circular die.
BLOW-UP RATIO
In tubular extrusion blown film, the ratio of the extrusion die diameter to the diameter of the blown film tube.
BLUSH, BLUSHING
Hazy or foggy appearance occasionally noted in coated films. Poor bond quality of solvent adhesives or in the appearance of lacquer-type coatings due to cooling from solvent evaporation, which condenses water in or on the coating, causing a white appearance.
BOAT
In vacuum metallizing, a resistance-heated source usually designed of an intermetallic composite to perform both the functions of heating and evaporation of the metal to be deposited. Made of combinations of titanium diboride (TiB), boron nitride (BN), and sometimes aluminum nitride (A1N), the heating of boats is done by electrical current passage through the material.
BON
Biaxially Oriented Nylon.
BOND STRENGTH
A measure of the strength of a bond between two adhered surfaces.
BOPP Films
BOPP films have excellent clarity, smooth surface, and good chemical & abrasion resistance. Selected BOPP films also provide resistanc to UV light and are preferred to achieve good moisture barrier.
BOWED ROLL
A type of spreader roller used for the removal of MD wrinkles during web transport. The curvature in the roll causes the center of the web to become tight and forces the wrinkles to the edges of the web. Sometimes referred to as a Banana Roll or a Mount Hope Roll.
BRAKE
A device which resists rotational movement of a roll of material, thus contributing to web tension control.
BREAK
Denotes a tear all the way across a moving web. The repair of a break is called a splice.
BREAK STRENGTH
The ability of a material to resist rupture by tension. A measure of the strength of paper, fabrics, films, and other materials.
BREATHING
Passage of gases into or out of a package. Certain films are designed to permit it.
BRIGHTNESS
The quality of whiteness intensity as emitted from the printed or unprinted surfaces. Also see Brilliancy.
BRILLIANCY
The brightness or apparent strength of a color to the eye. (This attribute of color corresponds to the loudness of sound–brilliancy represents the percentage of incident light reflected by an object, e.g., a perfectly white material has 100% brilliance while an absolute black material has 0%.}
BRITTLE
Easily shattered or broken. In cellophane and paper, usually the result of moisture loss.
BRUSHED FILM
A film that has been purposefully patterned using a method of imprinting moderate, long, longitudinal needle scratches in one surface of the substrate uniformly over the entire web.
BRUSHING
A very high density of longitudinal direction, fine, short, needle-like scratches appearing as though the film had been brushed. They can cover large areas or occur in discrete transverse direction bands or stripes.
BUCKLES
Defective roll formation usually caused by buildup of heavy internal pressures in the wound roll. Deep, narrow folds in the roll, generally running parallel to the transverse direction.
BUNDLE WRAP
Outer wrap used to package two or more articles for sale or shipment, as a unit.
BURSTING STRENGTH (Mullen)
The property of a material that is measured by the pressure required to rupture it under specified conditions.
BUTT SPLICE
The joining of two webs without an overlap; most often accomplished by the use of pressure-sensitive tape, heat-reactivated tape, etc.
BUTT-CUT LABELS
Rectangular labels in a continuous form in which the edge of one label is immediately adjacent to the edge of the next one in sequence.
CALENDER
A machine in which material is passed between heated steel rollers under pressure to achieve various surface finishes, thickness requirements, dimensional stability, etc.
CALENDER COATING
The process of coating substrates, such as paper or fabric, by passing both the coating and the substrate through calender rolls.
CALENDER CUTS
Defects caused by creasing or cutting of the web during the calendering process.
CALENDER FINISHED
That surface finish imparted to a substrate via a calendering process.
CALENDER SPOTS
Marks on a web caused by material sticking to a calender roll.
CALENDER STREAKS
Dark lines in paper, parallel to the grain, caused by uneven pressing and drying before calendering.
CALIPER
Thickness generally expressed in mils or thousandths of an inch. Other dimensions also used: microns, gauge, and points.
CARBON BLACK
A black pigment produced by the incomplete combustion of natural gas or oil. Useful as a black pigmentation for inks and paints as well as a reinforcing filler for the rubber industry.
CAST
A forming of a plastic film or sheet by pouring liquid resin onto a moving belt or by extruding a plastic material onto a highly polished stainless steel roll.
CAST-COATED PAPER (Gloss Paper)
A coated paper in which the coating is allowed to harden or set while in contact with a finished casting surface. Cast-coated papers have, in general, high-gloss properties.
CAST POLYPROPYLENE FILMS (CPP)
CPP films, have high heat seal characteristics, are some of the most preferred substrates in flexible packaging. Exhibits high clarity, smooth surface and better impact resistance. A polyolefin, providing sustainable laminate solutions; when combined with same family polymers (BOPP/CPP/LDPE)
CATALYST
A substance used to accelerate a chemical reaction without itself being involved in the end product of that reaction.
CD
See Cross Direction.
CEFLEX
Circular Economy for Flexible Packaging initiative. CEFLEX is a collaborative European consortium that aims to advance the recycling of flexible packaging materials, such as plastic films and laminates.
CELLOPHANE
A transparent film made of regenerated cellulose. Cellophane is inherently greaseproof and may be made moisture proof and heat sealable by suitable coatings.
CELLULOSE, REGENERATED
Cellulose that has been chemically treated, then regenerated as a transparent film.
CEMENT
In the adhesive sense, a substance bonding two materials by chemical or solvent action.
CENTER FOLDING
A web that has been folded in the center before winding; also a collapsed film bubble or tube that has been slit on one edge.
CENTER WINDING
A winding method whereby the driving force, supplying the tension, comes from the shaft through the center of the roll.
CENTER/SURFACE WINDING
A winding method where tension is supplied both from the center shaft and the rolls via a driven rider roller.
CENTIPOISE
A unit of measure for viscosity.
CHANNELING
See Tunneling.
CHARGE
The amount of raw materials introduced into a reaction vessel.
CHATTER MARKS
Crossweb lines caused by nonuniform releasing from a casting, chill, or applicator roll. Also called stripping lines.
CHECKING
See Crazing.
CHEEK-PLATES
Discs used at each end of paper or rolls of film to prevent “telescoping” of material.
CHICKEN WIRE
A diamond-shaped film defect usually appearing in tightly wound gaugy film, sometimes referred to as buckling.
CLARITY
Freedom from haze; transparency.
CLARITY
Freedom from haze; transparency.
CLEARING
Burnout of electrical faults in capacitors having vacuum-metallized electrodes. Also called self-healing, since the capacitor normally remains in working condition after clearing.
CLING
A tendency of adjacent surfaces to adhere to each other, as in blocking, except that a separation can be achieved without damage to either surface.
CLUTCH
A mechanism for providing a controlled amount of slippage between a drive and a driven member via the regulation of frictional or electromagnetic forces. In web winding or unwinding, it is used to vary drive or braking tension.
COAT HANGER DIE
A sheet or film extrusion die shaped internally in the form of a coat hanger. This type of die is said to yield better distribution of material across the full width of the extruded web and, thus, produces sheets without weld lines.
COATING
A layer or covering, usually applied in liquid form, then dried, which is adhered to the surface of a material. The outer covering of a film or web. The film may be one- or two-side coated. See also Dip-Coating, Kiss Roll Coating, Knife Coating, Powder Coating, Reverse Roll Coating, Roller Coatings, Tie Coating.
COATING WEIGHT
The weight of coating per unit area.
COATING, FILM
A coating applied to provide protective, decorative, pressure-sensitive, waterproof or heat-sealable qualities to the base sheet.
COATING, HEAT-SEAL
A coating, applied to a base sheet, which may be activated by heat to permit the fusion or seal of one section of the film to another.
COCKLE
Uneven puckered paper caused by poor remoisturization.
COCKLED EDGES
A sinusoidal scalloping of the slit edge. Dull or misaligned slitter knives cause the slit edge to be stretched prior to cutting, or the drawing of individual film wraps into high roll edges. Scalloping is due to the edge being slightly longer than the bulk of the web.
COEFFICIENT OF FRICTION (COF)
The ratio of the frictional to perpendicular forces between two surfaces. COF has a STATIC value which represents the force required to initiate sliding and a DYNAMIC value which represents the force required to maintain sliding.
COEFFICIENT OF THERMAL
The fractional change in length or volume, as specified, of a material per unit change in temperature.
COEXTRUSION
The process of extruding two or more materials through a single die with two or more orifices arranged so that the extrudates merge and weld together into a laminar structure before chilling. Each material is fed to the die from a separate extruder.
COF
Coefficient of Friction.
COHESION
The tendency of a mass to hold together by primary or secondary valence forces (intermolecular attraction).
COHESIVE STRENGTH
The resistance to splitting internally of a coating or adhesive.
COLD FLOW
A change in dimensions and/or shape of a material when subjected to external weight or pressure at room temperature. In adhesives, the usually undesirable movement or flowout of the adhesive.
COLD RESISTANCE
The ability to withstand the effects of low temperatures. Cold resistance properties include resistance to cold cracking, low temperature flexibility, etc.
COLD SEAL ADHESION
The amount of force required to pull or remove a cold seal adhesive from a substrate. The force is usually measured in grams/inch.
COLD SEAL RELEASE
A property of certain polymer films that allows them to be easily sealed without the need for heat. Cold seal packaging is a process where the adhesive used for sealing does not require heat activation. Instead, it adheres at room temperature or with minimal pressure. This is particularly advantageous for heat-sensitive products or when rapid and efficient packaging is necessary.
COLD WORKING
Plastic deformation of metal at such temperature and rate that strain-hardening occurs.
COLOR BURNOUT
An objectionable change in the color of a printing ink which may occur either in bulk or on the printed sheet. In bulk, it is associated primarily with tints and is caused by a chemical reaction between certain components in the ink formulation. On printed sheets, it generally is caused by heat generated in a pile of printed material during the drying of an oxidizing type of ink.
COLOR FASTNESS
The ability of a color in an ink or plastic to retain its initial appearance, regardless of time and exposure.
COLOR STRENGTH
The hiding power or intensity of a color system, such as a printing ink.
COLORIMETER
A device which compares the color of a substance with a set of known standards so that a numerical value can be assigned.
COLOR-OFF
In cellophane, slit roll edge may display variation in color or shade; off-color film is not usually defective, will almost always perform on machines.
COMET
In gravure printing, an extraneous ink film deposited in the shape of a comet, caused by the printing cylinder having been gouged by a hard foreign particle freeing itself from under the doctor blade.
COMPRESSION RATIO
In an extruder screw, the ratio of volume available in the first flight at the infeed end to the last flight at the end of the screw.
COMPRESSIVE STRENGTH
Crushing load at the failure point of a specimen divided by the original sectional area of the specimen.
CONDITIONING
The process of subjecting material to specified temperature and relative humidity conditions for a stipulated period of time.
CONDUCTOR
A body or substance which allows an electric current to move through it.
CONFORMABILITY
The ability of a material to bend around sharp corners or projections without tearing or fracturing. Sometimes expressed as the smallest mandrel around which the material can bend without physical damage.
CONSTANT TENSION, CONSTANT
A winding or unwinding mode in which the force applied to the core of the wind or unwind roll is kept at a constant regardless of diameter change.
CONTAMINATION
Matter which is foreign to or deleterious to the product or substance in which it is contained. Impurity.
CONTOUR PACKAGE
Package formed of semi-rigid material, usually by shaping a heated sheet by pressure or vacuum so that it follows the contours of the packaged item very closely.
CONVERTER, PACKAGING
Equipment which processes raw packaging stock such as cellophane, foil, etc. into a more advanced state, generally by forming, printing, gluing, laminating, etc.
CONVERTING
Altering, varying, transforming, modifying, deviating, or changing a material. Typical examples of converting processes include printing, laminating, slitting, and handling and storage.
CORDUROY
See Washboard.
CORE
A tube on which webs of material are wound.
CORE CHUCK
A mechanism for fixing a core onto a rotating shaft so that there is no slippage between the shaft and the core.
CORE DUST
Particle material abraded from a core during cutting or by slippage of core chucks during winding or unwinding. Collects upon roll faces or becomes wound between film layers to create pimples. High static levels in the film can aggravate the problem.
CORE PROTRUSION/RECESS
A situation that occurs when core ends are not flush with roll end faces due to improper core length or improper core alignment with the web. Some amount of core protrusion is frequently desirable for roll packaging purposes and handling.
CORE SIZE
Inside diameter of the core.
CORONA TREATMENT
To treat a surface such as polypropylene, polyethylene, etc., with a corona discharge (electrical sparks) to produce a wettable or printable surface. Exposing the surface to a high-voltage, high-frequency electric discharge increases oxygen concentration and surface energy.
CORROSION
Deterioration of a material by chemical action, usually as a result of galvanic, acid, or alkali action, oxidation of metals, etc.
CORRUGATIONS
A series of short, sharp longitudinal ridges appearing as a narrow band running in the transverse direction of the web surface. Also called TD Buckles.
COVERAGE
A measure of the ability of the coating or adhesive to be spread over a surface. Dry weight of coating or adhesive used per unit of area, usually 3000 square feet. In printing, the ability to obtain a complete opacity, eliminating the evidence of the base material’s color.
CRACKING (of coating)
Breaks in a coating which extend through to the base surface. Observation under magnification of 10 diameters is recommended where there is difficulty in distinguishing between cracking and checking.
CRASH
See Smash.
CRATERING
Thin or bare spots in a coated film that have the appearance of pock marks.
CRAWL LINES
Lines of uneven coating caused by wrinkles in the coating nip.
CRAWLING
A coating defect of beads and fish-eyes, occurring when the surface being coated has a lower intrinsic surface tension than the liquid coating.
CRAZING
Fine cracks in a coated surface, which may extend in a network on or under the surface of, or throughout, a film layer coating or adhesive or on surfaces of glazed materials such as glass, plastics, and painted or enameled surfaces. Also called “checking.” Fine cracks in a coated surface. Also called “checking.”
CREASES
Marks caused by foldovers usually due to wrinkles in a web material.
CREEP
The lateral movement of a pressure-sensitive label on a surface due to low cohesive strength.
CREEPAGE
The slight but continuous cumulative tendency of a color to drift out of register or position in the running direction.
CRIMP SEAL
Seal produced in cellophane or other material by means of elements having corrugated surfaces; lends mechanical rigidity to seal areas as well as ensuring maximum area contact of film surfaces.
CROCKING
Smudging or rubbing off of ink.
CROSS DIRECTION (CD)
The direction perpendicular to the machine direction. The direction at right angles to the direction of the machine orientation of films. Also referred to as the across or transverse direction (TD), cross grain, weft, and fill. Also see Machine Direction (MD).
CROSS LAMINATED
Pertaining to a laminate in which the reinforcing fibers in some layers are positioned at right angles with respect to the fibers in other layers.
CROWNED ROLLER
A roller with a larger diameter in the center than at either end. It can be used to remove the center of a web sag, or function as a member in a nip cluster when the crown compensates for roller load deflection. Wide-belt pulleys are sometimes shaped this way, which causes the belt to seek the center of the pulley.
CRUSH CUT
See Score Slitting.
CRYOGENICS (Vacuum System)
The use of subzero temperatures to entrap condensible gas molecules in a vacuum system.
CRYSTALLINITY
A state of molecular structure in some resins that denotes uniformity and compactness of the molecular chains forming the polymer. Normally, can be attributed to the formation of solid crystals having a definite geometric form. Degree of crystallinity can affect strength, flexibility, transparency, thermal stability, barrier properties, etc.
CUPPING
A slightly U-shaped deformation of tape (at right angles to the length) which usually appears after unwind tension is relaxed.
CURE
To treat a material by the application of time, heat, pressure, chemical agents, or combination thereof, to impart desired physical characteristics for a specific use. In adhesives, to change physical properties by chemical reaction, which may be chemical condensation, polymerization, or vulcanization; usually accomplished by the action of heat and catalyst, alone or in combination, with or without pressure.
CURL
In packaging films, distortion frequently caused by absorption or loss of moisture at an uneven rate from one side of a sheet; curl also may be caused by uneven physical stresses, as in the case of laminations or coated materials. An undesirable condition caused by uneven rates of absorption or evaporation of moisture, uneven rates of contraction or expansion, or internal stresses in the material. Curl is most prevalent in coated or laminated materials where the components have differing physical properties. Curl in unsupported films may be caused by distortion resulting from excessive tension while winding in rolls or by static reaction.
CURTAIN COATING
A method of coating which may be employed with low-viscosity resins or solutions, suspensions, or emulsions of resins in which the substrate to be coated is passed through and perpendicular to a freely falling liquid “curtain” (or “waterfall”). The flow rate of the falling liquid and the linear speed of the substrate passing through the curtain are coordinated in accordance with the thickness of the coating desired.
CURVATURE
The variation in the length of film from side to side.
CUT-OFF LENGTH
Length of sheet fed by automatic wrapping machine during operation.
CYCLE TEST
Test program in which items are exposed alternately to two or more test conditions.

 

DANCER ROLLER
A free-moving, counter-balance roller which can displace with changes in web tension. Its function is to sense web tension and/or dampen tension transients.
DARK REACTION
A phenomenon in which ultraviolet inks usually turn solid at the bottom of the can when the shelf-life of the material has expired. This is called a dark reaction because it occurs in the absence of light, oxygen, and normal ink bodying agents. (Oxygen tends to inhibit the solidification of ultraviolet-curable compounds, so stirring in air may improve shelf-life.)
DART
See Comet.
DEAD SOFT
Fully annealed aluminum foil.
DEAD STRETCH
The net stretched length after tape has been elongated without breaking and allowed to recover.
DEADFOLD
A hand- or machine-made fold that remains in position without sealing or pressure, such as on a soft foil.
DEBOSSED
An indent or cut-in design or lettering of a surface.
DECKLE
The process of controlling the width of extruded plastic films and coatings.
DECKLE ROD
A small rod, or similar device, inserted at each end of the extrusion coating die, used to adjust the length of the die opening.
DELAMINATION
Partial or complete separation or splitting, usually caused by lack of adequate adhesion in laminated or plied materials.
DELAYED STAIN
See Latent Stain.
DENSITY
The mass of a unit volume. Opacity, color, strength. Weight per unit volume of a substance, expressed in grams per cubic centimeters, pounds per cubic foot, etc.
DE-SIZING
A method for removing size material in preparation for dyeing, etc.
DESTATICIZATION
Treating plastic materials to minimize accumulation of static electricity, thus reducing the amount of dust pickup due to static charges.
DIAZO
A photosensitive chemical or process by which screen printing emulsions can be made sensitive to actinic light
DIE
A steel block containing an orifice through which plastic is extruded, shaping the extrudate to the desired profile. Any of various tools or devices used for imparting or cutting a desired shape, form, or finish to or from a material.
DIE CUT
The line of severance between a desired shape and its matrix or adjoining material made by the cutting edge of a die.
DIE CUTTING
The process of cutting shapes from sheets of plastic by pressing a sharp knife edge into one of several layers of sheeting. The dies are often called steel rule dies and pressure is applied by hydraulic or mechanical presses.
DIE DRIPS
Degraded polymer that is deposited on and processed with the extruded films.
DIE LINES MD
MD surface marks on extruded plastic films or coatings. Also called “lip streaks.”
DIE PRESS
A machine for die cutting material by direct pressure.
DIE UPS
Deformable member(s) attached to a die body which determines the slot opening and is adjusted to produce uniform thickness across the film or sheet produced.
DIE-CUT LABEL
A pressure-sensitive label mounted on a release liner from which the matrix has been removed.
DIELECTRIC
An electrical insulating material.
DIELECTRIC CONSTANT
The ratio of the capacitance of a dielectric material compared to the capacitance of air under the same conditions.
DIMENSIONAL STABILITY
The property of a material which relates to the constancy of its dimensions. The ability of a material to resist dimensional change with time under certain conditions, such as humidity, pressure, heat, etc.
DIMPLES
Small protrusions or indentations on the surface of a roll of plastic film, foil, or paper resulting from pressure exerted by contamination or defects wound into the roll.
DIP-COATING
A coating applied by dipping an article or web into a tank of liquid.
DIRECT GRAVURE
The direct depositing of a coating onto a web from depressions of a specific length, pattern and spacing, which have been either laser, mechanically, or chemically engraved into a printing cylinder. The gravure cylinder, backing roll, and web all move in the same direction.
DISHING
The progressive roll edge misalignment which causes roll end faces to become concave or convex. It can occur during roll winding, unwinding, or handling. Also see Telescoping.
DISPLACED TURNS
A condition in which single film wraps or layers of wraps in a roll are displaced in the transverse direction.
DOCTOR BLADE
An adjustable, thin, knife-like bar that wipes coating off the surface of a smooth roller or gravure roll.
DOCTOR ROLL
A roll which operates at a different speed or in the opposite direction, as compared to the primary roll of a coating machine, thus regulating the uniformity and thickness of the coating.
DOCTOR-BLADE
Scrapers that regulate the thickness of adhesives, or inks, on a feed roller.
DOUBLE-FACED
A sign, display, or tape printed or coated on both sides of a sheet.
DOUGHNUT
In printing, the appearance of the circumference of a screen dot with no ink in the center.
DOWNGAUGE
Use a thinner film than had been previously used.
DRAG-OUT
A bead of excessive ink which appears at the trailing edge of the print
DRAW
The forward and/or sideways stretching of a film during orientation.
DRAWDOWN
Thinning of gauge or narrowing in width, especially of extruded materials, as a result of windup rate exceeding extrusion speed. A thin layer of ink or coating applied and spread by a variety of instruments or hand rollers or by pulling a smooth, flat knife blade over a small sample and continuing to draw the blade under pressure. Also called “pulldowns,” drawdowns are used to check characteristics such as shade, color strength, tones, etc.
DRAWDOWN RATIO
The ratio of the thickness of the die opening to the final thickness of the product.
DRAWING
The process of pulling material through a die to reduce the size, change the cross section or shape, or harden the material.
DROOP
The condition in which the edges of a web sag or become misaligned with the center.
DRYING IN
The drying of a coating or ink in the cells of the engraving roll. This coating must be completely removed by washing with solvent prior to rechroming a cylinder.
DULL FINISH
Any finish which lacks luster but is somewhat smooth. Any smooth surface which lacks luster or brilliance.
DUPLEX SLITTER
A type of slitting machine (usually center winding) having two rewind mandrels. These mandrels may be equipped with differential rewinding mechanisms.
DUROMETER HARDNESS
The relative hardness of an elastomeric material such as a roller covering.
DYNAMIC BALANCING
The act of removing forces which cause roller vibration during rotation. This is done by rotating the roller at design speed and measuring the forces causing an out-of-balance condition for subsequent correction.
DYNE
A measurement unit of force (centimeter-gram-second) traditionally used to quantify the energy on the surface of a film as an indicator of its ability to accept inks or coatings.

 

EDGE CURL
The lifting of the outer edge(s) of a web material. Also see Curl.
EDGE GUIDE
A device for maintaining the location of a web edge at a predetermined point. It usually consists of an edge sensor (pneumatic or optical) and some mechanism for displacing web tracking.
EDGE PLATES
See Edge Protectors.
EDGE PROTECTORS
Hard fiber or heavy board used to protect the ends of rolls in packing. Also called “edge plates” and “flanges.”
EDGE WEAVE
An irregular roll edge appearance due to oscillation of the web during winding.
ELECTROLYSIS
The decomposition of a compound by means of an electric current.
ELECTRON BEAM
The process by which accelerated electrons form a curtain through which the web passes. The energy available from these accelerated electrons initiates chemical reactions (cure) for coatings and adhesives.
ELECTRONIC SEALING
Sealing of surfaces in contact with one another by high frequency current, e.g., sealing vinyl sheet. Heat is generated within the film by high-frequency agitation of the sheet’s molecular structure.
ELECTROPLATING
The deposition of one metal upon another as a thin surface, by subjecting a solution of the corresponding metal salt to electrolysis.
ELECTROSTATIC DISCHARGE
The result of a charged body approaching sufficiently close to the conductor for the air molecules between them to conduct the current.
ELECTROSTATIC PRINTING
A method of printing in which the ink is affixed to the web by electrostatic method.
ELECTROTYPE
A photo engraving on copper for printing pictures by halftone process.
ELMENDORF TEST
A standard test to determine the tear propagation resistance of a web material, i.e., paper, films, or foils (ASTM D1922).
ELONGATION (Stretch, Ultimate Elongation)
The distance a material will stretch lengthwise before breaking, expressed as a percentage of its original length (ASTM D882).
EMBOSS
To create a design on a surface by causing the letters, figures, patterns, etc., to be raised by pressure of dies, rollers, printing press, etc.
EMBOSSING
A technique used to create depressions of a specific pattern in plastic, film, or sheeting. The relief impression on a web or sheet left by a predesigned raised surface of a roller, such that the sheet retains the pattern thus embossed into it.
EMISSIVITY
The capacity of a material to emit radiant energy. Emittance is the ratio of the total radiation emitted by a body to that emitted by an ideal black body at the same temperature. Emissivity is an intrinsic property of all materials.
EMULSION
A non-separating dispersion or suspension of a solid in a liquid.
ENCAPSULATED INK
Ink covered or enclosed with a coating giving a free-flowing dry system that can be activated by heat or pressure.
ENGRAVING
The act of removing surface material by mechanical, chemical, or other techniques; usually from a roller or plate.
ENVIRONMENTAL STRESS CRACKING
The susceptibility of a thermoplastic article to crack or craze under the influence of certain chemicals and stress.
ERASABILITY
That property of a sheet that permits writing on the sheet to be removed by erasure and resists erosion by erasure. After erasure, the sheet should present a satisfactory appearance and permit rewriting on the area.
ESC
See Environmental Stress Cracking.
EVAPORATOR BOAT
See Boat.
EXTENSOMETER
An instrument for measuring any deformation of a test specimen caused by tension.
EXTRUDATE
The product or material delivered from an extruder; for example, film, pipe, profiles, wire, coatings, etc.
EXTRUDER
A machine for producing more or less continuous lengths of plastic sections such as rods, sheets, tubes, profiles, and cable coatings.
EXTRUSION
The process of melting plastic resins under heat and pressure and forcing the molten material through an orifice.
EXTRUSION LAMINATION
A process for joining two webs by feeding them through a machine that extrudes a thin layer of plastic between them to act as an adhesive.

 

FABRIC
Cloth; textile. The product resulting from weaving, felting, knitting, knotting, bonding, or crocheting natural or synthetic fibers or filaments.
FACE CUTTING (Kiss Cutting)
Cutting the face sheet to desired design without cutting the backing or support sheet.
FACE MATERIAL
Body stock; face stock. Any paper, film, fabric, laminate, or foil material suitable for converting into pressure-sensitive labelstock. In the finished construction, this web is bonded to the adhesive layer and becomes the functional part of the construction.
FACE-CUT LABEL
A die-cut label product from which the matrix has not been removed.
FADING
The loss of color strength on exposure to light, heat, or other agents.
FADOMETER
A mechanical device that measures the effect of light upon a material.
FALLING DART TEST
A method of measuring the impact resistance of thermoplastic films by dropping a dart with a hemispherical head onto a restrained film specimen usually held by a clamping frame (ASTM D1709).
FANFOLD
Zigzag fold: flat pack. The application of pressure-sensitive labels on a continuous backing in such a way as to form a flat pack, as differentiated from roll form.
FATIGUE
A condition of stress induced by repeated flexing or impact force upon a material.
FEATHERING
The appearance of small irregular edges around a print. Can be caused by improper roller pressures, inks drying on the plate, too heavy an ink flow, or lint being picked up from the material. Also see Smash.
FEEDSLOTS
Index holes; index punch; pin feed; line hole punching; marginal punching. Round or rectangular holes or slits put in pressure-sensitive labelstock to maintain the register of pressure-sensitive labels during printing or imprinting.
FESTOON
A method of drying a coated web or solvent cast film by conveying it through a drier by looping or threading the material over and under rollers.
FILAMENT WINDING
Roving or single strands of glass, metal, or other reinforcements wound in a predetermined pattern onto a suitable mandrel. The pattern is designed to give maximum strength in the directions required. The strands can be run from a creel through a resin bath before winding or preimpregnated materials can be used. When the proper number of layers have been applied, the wound mandrel is cured at room temperature or in an oven.
FILAMENTS
Thin longitudinal continuous “threads” of glass, rayon, nylon, or other material of high strength.
FILL
The maximum width of paper that can be made on any given paper machine. Also see Cross Direction.
FILL-IN
Printing difficulty caused by a speck of pigment or foreign matter in ink becoming jammed between the dots in screens or in small type and other ink building onto it. Also called PILE or SPECKING.
FILM
A uniform, thin (0.00025-0.032 inch) substrate manufactured from synthetic polymers such as polyvinyl acetates, polycellulosics, polyester, polyethylene, polycarbonate, polypropylene, etc.
FILM CAST
Generally refers to film made by coating or casting a solution of a polymeric material on an endless belt or wheel, drying the solvents, stripping the film from the belt and winding after additional drying. Also applied to film thermally extruded onto a casting roll.
FILM DENSITY
The ratio of the weight of a body to the weight of an equal volume of water at some specified temperature (same as SPECIFIC GRAVITY).
FILM FORMING
The property or ability of a substance to cast a continuous film.
FILM, CALENDERED
A film manufactured by forcing base material through rolls of a calendering machine, making it smooth and glossy.
FILM, CAST
(1) Film made by pouring or metering material onto a highly polished moving drum or endless belt, or (2) film produced by extruding into a solution, as in the case of cellophane.
FILM, EXTRUDED
Film produced by the extrusion method.
FILM, NON-FOGGING
Film that does not become cloudy from condensation of moisture caused by temperature drops or humidity changes.
FILM, ORIENTED
Film in which the molecular structure is aligned mechanically in one or more directions, thus giving the film more strength while introducing shrinkage characteristics.
FIN SEAL
Seal that results when edges of two superimposed sheets are bonded, resulting in a pouch having fin-like protuberances.
FINISH
The degree of gloss or flatness on a surface print.
FINISH, MATTE
A dull finish; flat; low gloss.
FIRE POINT
The temperatures at which a flammable liquid will burn for five seconds after ignition
FISH-EYE
Particles of undissolved or extraneous material in a film or coating resembling the eye of a fish.
FLAG
A small tab inserted near the end of a roll to signal roll run-out.
FLAME RESISTANCE
The ability of a material to withstand exposure to flame. Fireproof materials will not burn even when exposed to flame. Flame-resistant (fire-retardant, self-extinguishing) materials will burn when exposed to flame, but will not continue to burn after the flame is removed.
FLAME TREATMENT
A method of rendering inert thermoplastic objects or webs receptive to inks, lacquers, paints, adhesives, etc., in which the object is bathed in an open flame to promote oxidation of the surface (similar in effect to corona treatment).
FLAMMABILITY
The ease with which a material (gas, liquid, or solid will ignite, either spontaneously from exposure to a high temperature environment or to a spark or open flame. It also involves the rate of spreading of a flame once it has started (ASTM D3801).
FLANGES
See Edge Protectors.
FLARED EDGE
See Bead.
FLASH POINT
The lowest temperature at which a flammable liquid will burn momentarily (flash) when ignited by a small flame passed over the surface.
FLAT
In printing, dull, lacking contrast and definition of tone, opposite of glossy. The degree of freedom from curl, cockle, wrinkles, bagginess, etc., sometimes called layflat or planarity.
FLAT SEAL
A method of heat sealing thermoplastic films with a flat bar surface.
FLEX CRACK
Cracking in a film produced by repeated flexing.
FLEX SPREAD ROLLER
A rubber-covered roll, grooved with a narrow pitch from the center of the face to each end, used to help maintain a flat web of thin film. A type of spreader roller used for the removal of MD wrinkles during web transport. Such a roller has counter spiraling grooves cut in its elastomeric covering to effect a spreading from the center of the web outward. Sometimes referred to as a Bingham Roller.
FLEX STRENGTH
The ability of a sheet or film to withstand breakage by folding. Measured by a test to determine the number of folds required to cause failure.
FLEXIBILITY
Conformability; pliability; hand. A property of face materials measured under specified conditions that indicates how readily they will conform to curved surfaces.
FLEXOGRAPHIC PRINTING
A method of rotary letterpress printing that employs flexible rubber plates and rapid drying inks.
FLEXURAL STRENGTH
The ability of a material to withstand breakage by folding. Flexural strength may be measured by a test to determine the number of folds required to cause failure. Also flexing strength. Also see Fold Endurance and M.I.T.-Fold Endurance (ASTM D790).
FLOATING KNIFE
Method of applying a coating to an unsupported web. Also see Knife Coating.
FLOCKING
A method of finishing, sometimes employed for plastic articles, whereby an article is coated with a tacky, slow drying adhesive and then dusted with a fibrous material cut into very short lengths to give a finish resembling suede or other fabrics.
FLOODING
The application of an unmetered, excessive amount of coating, upstream of a metering device.
FLOW OUT
The ability of a coating to level after application (whether brushed, sprayed, roll, or applied through pressure units). “Orange peel” is the surface appearance when a material does not flow or level. Excessive flowing on vertical surfaces is termed “sagging” and is usually due to an excessive amount of material or slow drying solvent.
FLUID BED
A material in powder form kept suspended by an upward draft of air.
FLUOROCARBON FILMS (Fluoropolymer Films)
A family of plastic films composed of polymers that are partly or totally based on monomers containing fluorine to carbon bonding. Materials so composed generally have one or more of the following characteristics: broad temperature limits; excellent electrical properties; excellent moisture and gas barrier; excellent chemical resistance; low coefficient of friction; low specific surface energies
FLUTING
Distortion of a roll such that layers no longer form a circle.
FLYING SPLICE
Adhering the leading edge of a new roll to the tail edge of the current roll while the machine is in motion.
FLYSPECKS
Particulate contaminants internal to a film, more easily detected by inspection in transmitted light between polarizing filters.
FOAM
A soft, cushiony material formed by creating bubbles in base materials, such as natural or synthetic rubbers (or other elastomeric materials).
FOIL/PAPER LAMINATE
A metal foil or metallized film laminated to paper, used as a facestock or facing material. The foil or film usually is treated or coated to improve ink receptivity.
FOLD ENDURANCE
The number of double folds a material will endure before rupture. Also see M.I.T.-Fold Endurance (ASTM D2176).
FOLDOVER
An amount of film or other web material which folds in within the same layer. This is usually the result of improper tension, temperature, or differential expansion of the web during a drying process.
FRACTIONAL PACKAGING
Interior packaging of individually wrapped units so that unused portions will be protected after outside package has been opened. Usually used for biscuits, crackers and ready-to-eat cereals.
FUSE
Weld of thermoplastic materials by heating to point just above that at which they soften.
FUSED EDGES
Edges that are thermally or chemically fused giving the appearance of a concentric edge on the end of the roll.
FUZZY EDGES
Edges of a slit roll that exhibit protruding fibers due to poor slitting.

 

GAS PACKAGING
Packaging in a gas-tight container in which air has been replaced by a gas such as carbon dioxide or nitrogen.
GAS TRANSMISSION
The movement of gas, air, oxygen, etc., through a film material. The gas transmission property (permeability) of a film is measured in terms of the volume of gas (at standard temperature and pressure) transmitted through a given area of film of a given thickness, within a given time.
GAS TRANSMISSION RATE
A measure of the permeability of a material to gases by measuring the movement of a gas through the film under specified conditions. In most cases, gas transmission rates are reported in cubic centimeters per 100 square inches per 24 hours at 1 atmosphere pressure and 75 degrees Fahrenheit (ASTM D14341).
GASSING
(1) Development of gas in a sealed package. (2) Removing air from a filled package and replacing it with another gas such as carbon dioxide or nitrogen.
GAUGE
Thickness of a material measured in hundred thousandths of inches, decimals, mils, or microns. A standard measure, usually of thickness or diameter, expressed by a number which has a standard dimensional equivalent that varies for different materials and for different standards. An instrument for exact measuring (see caliper). To measure exactly. In film, a method of indicating thickness in which the numerical prefix is the last figures of the five-digit decimal fraction of the inches of thickness; thus 88 gauge = 0.00088 inch.
GAUGE BAND
A continuous lane of film web that has abnormal machine direction thickness compared to the adjacent film web.
GAUGE-OFF
Not within specified dimensions of thickness.
GEL
An imperfection caused by cross-linked, degraded, unmelted, or undissolved polymer granules appearing in a plastic film or extrusion coating.
GHOSTING
Reproduction, very faint, of printed design without actual ink transfer.
GLASSINE
A super-calendered, smooth, dense, transparent or semitransprarent paper manufactured primarily from chemical wood pulps which have been beaten to secure a high degree of hydration of the stock.
GLASSINE, COATED
The coating types available include hot-melt-applied paraffin waxes and derivatives, as well as solvent-applied types made from cellulose nitrate, vinyl polymers and other synthetic or natural rubber polymers.
GLASSINE, LAMINATED
Glassine laminated to itself, or other paper, films and foils, to obtain added strength and made-to-order protective water-vapor properties.
GLITTER
Metallized plastic films cut or chopped into small pieces. Each flake produces a plainly visible sparkle or reflection when incorporated directly into a plastic during compounding.
GLOSS
A term used to express the shine, sheen, or luster of the dried film. If a surface clearly and plainly reflects the image of light, it has a high gloss. Absence-of-bloom gloss is indicated by freedom from haziness bordering a highlight. Contrast gloss is expressed as a fraction whose denominator is the apparent-reflectance of the sample when illuminated in a direction other than the perpendicular and viewed in the direction of a specular reflection, and whose numerator is the same apparent-reflectance diminished by the apparent-reflectance of the sample identically illuminated but viewed perpendicularly. A measure of surface reflection. A high gloss surface reflects most of the incident light and usually measured at an angle of 20-30 degrees from the vertical.
GRAINY
A rough finish due to shrinkage of paper, particularly at the edges of the web. In printing, when the ink film has a pebbly rather than a smooth appearance.
GRAVES TEAR TEST
The measurement of a film to resist tearing initiation (ASTM D1004).
GRAVURE PRINTING
An intaglio printing process employing minute engraved “cells.” In general principle, deeply etched cells carry more ink than a raised surface, hence print darker values. Shallow cells are used to print light values. A doctor blade wipes excess ink from the cylindrical printing surface. Rotogravure employs etched cylinders and web-fed stock. Sheet-fed gravure, as its name implies, involves individual sheet feeding. Also see Rotogravure Printing.
GRAVURESCOPE
A special type of microscope designed for inspecting and measuring the engraved cells on an anilox roll or a gravure cylinder, both vertically for depth and horizontally for width.
GREEN TACK
The bond strength of an uncured adhesive when the bond is first formed.
GUILLOTINE
An instrument for trimming paper or film with a downward cutting action.
GUSSET
A fold or tuck on the side of a bag, pouch, or web.

 

HALO
An unwanted line surrounding a printed image. See Feathering and Smash.
HAND
That softness or flexibility of a film, fabric, or coated fabric as judged by the touch of a person.
HAND BAND
That portion of a roll of film or other web material exhibiting a lane of thick gauge in the web. Also see Gauge Band.
HARD CREASE
A folding or pleating of the web during winding, compressed by subsequent layers of the roll. Normally, can only be removed by a combination of overtension and heat being applied to the afflicted area.
HARD EDGES
Caused by slitting at the gauge band.
HARD WINDING
Roll rewound under great tension; roll rewound under excessive tension.
HAZE
Cloudy or foggy area in an otherwise clear film or sheet. A cloudy or foggy appearance in a normally transparent material.
HDPE
Abbreviation for high density polyethylene.
HEAT LINES
Machine direction lines that have a crease-like appearance due to uneven shrinkage from excessive heat.
HEAT SEAL
An adhesive coating intended to be reactivated by the application of heat to one or both of the surfaces to be bonded; the process of bonding plastic substances by bringing the adhered surfaces to their melt points under contact and continuing pressure.
HEAT-CURING ADHESIVE
Adhesives that require a definite period of time above room temperature to develop full bond strength. They can be of one- or two-part compositions.
HERMETIC SEAL
A seal that will exclude air and be leak-proof.
HIDING POWER
The use of paint or pigment to obscure or render invisible a surface over which it is applied. It is one of the most important physical properties of a white pigment. It is determined by the difference in index or refraction between the material and its surrounding medium.
HIGH EDGES
Raised or flared edges extending above the surface of the main body of a roll. Usually caused by dull or misaligned slitter knives causing slit edge flaring or thickening, which stacks to cause pronounced high edges. Also see Bead.
HOT MELTS
Thermoplastic materials used as adhesives and coatings that normally are solid at room temperature but become sufficiently fluid when heated to be pourable or spreadable.
HOT STAMPING (Roll Leaf)
A method of marking in which a special pigmented, dyed, or metallized foil is pressed against an article by a heated die, welding selected areas of the foil to the article. It also includes the process of impressing inked type into the material when the type is heated.
HOT TACK
The property of an adhesive or seal layer to resist forces that would pull the seal apart while it is still hot.
HOT-STAMPING MACHINE
Marking machine that applies a code mark or date on a package or a wrapper with a heated stamp.
HUMIDITY
Water vapor in the air. Absolute humidity is the actual weight of water vapor contained in a unit weight of air. Relative humidity (RH) is the ratio of the actual humidity to the maximum humidity which air can retain without precipitation at a given temperature and pressure. Expressed as a percent of saturation.
HYDROEXPANSIVITY
That property of a material that causes it to expand or contract when its moisture content is changed (as when the relative humidity of the surrounding atmosphere is changed).
HYGROMETER
An instrument for measuring the moisture of relative humidity in the atmosphere.
HYGROSCOPIC
Having the property of absorbing moisture readily from the atmosphere.

 

ID
Inside diameter.
IMPACT RESISTANCE
See Falling Dart Test.
IMPACT STRENGTH
Resistance of a material or product to shock, such as from dropping and hard blows.
IMPREGNATION
Saturation of a material with another substance.
IMPRINTING
A technique in which changeable copy is applied to blank or previously printed labels, tags, etc., with a secondary printing device such as an imprinter, computer, typewriter, etc.
IMPULSE SEALING
A heat-sealing technique in which a pulse of intense thermal energy is applied to the sealing area for a very short time, followed immediately by cooling. It is usually accomplished by using a radio frequency (RF) heated metal bar which is cored for water cooling or is of such a mass that it will cool rapidly at ambient temperatures.
INDENTATlONS
Permanent deformations in a web usually caused by the material overwrapping a pimple. Those caused by pimples in a slit roll will usually replicate with the roll circumference. Also see Dimples.
INDUCTION
A method of generating heat used in vacuum metallizing and drying.
INERT ATMOSPHERE
Atmospheric environment composed of nonchemically reactive gases. Often used to refer to exclusion of oxygen via nitrogen blanketing.
INFEED
A mechanism designed to control the forward travel of the web into a press.
INK, GRAVURE
Pigment dissolved or dispersed in a vehicle made from resins and solvents; very fast drying.
INK, IMPRINTING
Ink specially designed to be used with a marking device.
INK, MOISTURE-SET
Ink formulated to be stable under normal humidity conditions, but to set up or harden when exposed to very high humidity.
INK, THERMOSETTING
Ink formulated to be stable and free from tack at ordinary temperature but to set up quickly at elevated temperatures.
INSTRON
An instrument widely used to determine the tensile and compressive properties of material.
INTAGLIO
Rotogravure printing often characterized by an embossing effect on the substrate being printed.
INTERLEAVE
An inserted sheet, normally paper, that separates adjacent surfaces of a stack or roll of material to prevent damage or blocking.
INTERNAL MIXERS
Mixing machines which use the principle of cylindrical containers in which the materials are deformed by rotating blades or rotors. The containers and rotors are cored so that they can be heated or cooled to control the temperature of a batch. These mixers are extensively used in the compounding of plastics and rubber materials and have the inherent advantage of keeping dust and fume hazards to a minimum.
IRONING ROLL
A roll frequently used in coating or laminating operations to assist in keeping the web flat as it winds. Also see Lay-on Roller.
IRRADIATION
The subjection of a material to radiant energy for the purpose of producing a desired effect.
IRREGULAR WINDING (Lateral weave)
A defect whereby a difficulty shows up as failure of film to feed in straight line during use.
IRREGULAR WINDING (Projecting film)
Peaks or ridges in a slit roll that extend out more than 1/32” from edge of main body of roll.
IRREGULAR WINDING (Projecting Film)
Peaks or ridges in a slit roll which extend more than 1/32 inch from edge of main body of roll.

 

JOX
See Accumulator.
KISS
The lightest possible impression that will transfer a film of ink or coating from the transfer roller to the plate and from the plate to the web. Also see Kiss Cutting.
KISS CUTTING
Die cutting of a face material of a laminated substrate without cutting the support material.
KISS ROLL COATING
A method for applying a film coating to a web using a roller. The key element of this technique is that there is no backing roller at the point of contact.
KNIFE COATING
A method of adhesive, coating, or sealer applications consisting essentially of a rigid blade, which is adjustably mounted above a roll. Fluid coating material is placed behind the blade so that it is pulled under the blade. Sometimes referred to as “spread coating.”
KNURLED
A pattern applied to the edge of a web to prevent surface contact and blocking. The pattern is generated by an engraved metal roll. Some applicator rolls have a knurled surface.
KRAFT
A sulphate wood pulping process, also refers to paper made from such pulp.
L/D RATIO
A term used to define an extrusion screw which denotes the ratio of the screw length to the screw diameter.
LABEL
An identification method affixed to a package or container to transmit information. The functional portion of a pressure-sensitive construction comprising the face sheet and adhesive, die cut into various shapes. Usually printed and affixed to a package or container to identify the contents.
LABEL ROLL
Labels produced in continuous strips of pressure-sensitive substrates packaged in a continuous roll form.
LABEL SHEET
Labels that have been produced for packaging in sheet form.
LABEL, HEAT SEAL
A label coated on one side with a heat-seal coating; usually a thermoplastic resin.
LAMINATE
A product made by bonding two or more layers of material. The term most usually applies to preformed layers joined by adhesives or by heat and pressure. It also applies to composites of plastic films with other films, foil, and paper even though they have been made by spread coating or by extrusion coating.
LANNING
See Railroad Tracks.
LAP JOINT
A joint made by lapping one material over another to provide a mated area that can be joined with an adhesive.
LAP SEAL
Any seal made between two overlapping films. Used in contrast to a “fin seal”.
LATENT STAIN
A stain in a surface to which tape has been applied, which does not become noticeable until some time after removal, usually after the surface has been exposed to sunlight or heat.
LAYFLAT
A flexible material or an adhesive lamination that does not exhibit curl or distortion. The form of a film which is extruded as a tube, usually blown, then flattened by rollers and wound up. Also see Flat.
LAY-ON ROLLER
A roller in contact with the face of a winding roll. Its function is normally to aid in the expulsion of air from a wind, help transport the web to the wind, and assure uniform winding tension distribution across the roll face. It may be driven to apply a winding torque for surface and center/surface winding modes. Lay-on rollers also are called “rider,” “ironing,” or “tracking” rollers.
LDPE
Abbreviation for low density polyethylene.
LEGGING
The stringing out of a pressure-sensitive adhesive when a label is drawn away from a substrate, its release liner, or its matrix.
LETTERPRESS PRINTING
A printing process in which ink is applied to paper, board, or films from raised portions of printing plates or type.
LEVEL
The ability of an adhesive or coating to flow sufficiently upon application so that the exposed surface will be relatively flat and free from corrugations or other irregularities resulting from application.
LIFTING
A situation where a section of tape or label has pulled away from the surface to which it has been applied.
LIGHT STABILITY
A measure of the ability of a pigment, dye, or other colorant to retain its original color and physical properties, either alone or when incorporated into plastics, paints, inks, and other colored films or surfaces, upon exposure to sun or other light. Ability of a plastic or other organic film or surface to withstand the deteriorating effect of exposure to sun or other light independent of the stability of any pigmentation it contains.
LIGHT STABILIZER
An agent added to a plastic compound, ink, or coating to improve its resistance to light.
LIGHT TRANSMISSION
Percentage of visible light transmitted through a material. Calculated from optical density measurement on an optical densitometer.
LIP
That part of the tube of a flat or square bag, or pouch, extending beyond the face of the bag.
LIP STREAKS
Same as “die lines.”
LITHOGRAPHIC PAPER
A paper coated on at least one side; suitable for lithographic printing.
LITHOGRAPHY, OFFSET: 
Printing process using etched metal plates. Ink adheres to etched area, is transferred to rubber printing blanket, from there to paper to be printed.
LLDPE
Abbreviation for linear low density polyethylene.
LOOSE WIND
Wind made loosely due to entrapped air or insufficient tension, often resulting in “telescoping.”
LOW FINISH
A lack of glaze or gloss.
LUBRICANT BLOOM
A cloudy appearance or greasy feel on a plastic film.
LUG
An indentation or raised portion of the surface of a container, provided to control automatic (multicolor) decorating operations.

 

M.l.T.-FOLD
A test to measure the ability of a material to resist breakage due to repeated folding (ASTM D2176). Also see Fold Endurance.
MACHINE DIRECTION (MD)
In the manufacture of film, paper, or board, the majority of fibers tend to align in a direction parallel to the direction of travel through the machine. Similarly, in the manufacture of films, the molecules tend to orient in a direction parallel to the direction of machine travel. The direction of alignment or orientation is also referred to as “longitudinal” and “with the grain” and is at the right angle to the cross direction. Also see Cross Direction.
MAKE-READY
In printing, preparation of press for a run; especially, making all printing surfaces uniform in height.
MANDREL
In extrusion, the central finger of a pipe or tubing die. The support shaft for unwinding or rewinding rolls of paper, film, or foil.
MARGINS
Metal-free stripes running the entire length of the web in vacuum-metallized dielectric films for capacitors. When two metallized films are wound together to form a capacitor, the metal-free margin on each of the two rolls serves to insulate the edges of the two metallized electrodes from each other.
MASTER ROLL
The large roll of film wound during a film formation process, which is normally slit into smaller rolls for later processing or shipment.
MASTERBATCH
A plastic compound which includes a high concentration of an additive. Masterbatches are designed for use in appropriate quantities with the basic resin or mix so that the correct concentration is achieved. For example, color masterbatches for a variety of plastics are extensively used as they provide a clean and convenient method of obtaining accurate color shades.
MATRIX
The face and adhesive layers of a pressure-sensitive construction surrounding a die-cut label which are removed after die cutting.
MATTE FINISH
A dull or flat finish.
MAYER ROD
A wire-wound rod used to meter adhesives and coatings.
MD
Abbreviation for machine direction. See Machine Direction
MD BAND
A fine, longitudinal direction buckle on the roll surface that sometimes spirals around the full roll circumference. Most common to thin-gauge films, the defect usually only affects the outermost wraps.
MELT TEMPERATURE
The melting point of a polymer, sometimes properly termed a melting range since a specimen consists of more than one molecular weight and more than one crystal size. It is the temperature at which the polymer becomes molten.
MEMORY
That property of a plastic material that causes it to revert in dimension to a size previously existing at some stage in its manufacture.
METALLIZED FILM
A plastic or resinous film that has been coated on one or both sides with a very thin layer of metal by vacuum deposition or sputtering.
METALLIZING
The process of applying a thin coating of metal to a nonmetallic surface. May be done by chemical deposition or by exposing the surface to metal in a vacuum chamber.
METAMERIC MATCH
Color samples which match in one light source but not in another due to different absorption levels. When dissimilar, pigments are used to obtain color.
METERING ROLL
A roll parallel to a coating applicator roll. The gap between the two rolls determines the amount of coating transferred to the web. Also see Doctor Roll.
METERING SCREW
An extrusion screw which has a shallow constant depth and a constant pitch section over the last three to four flights.
MICRON
One millionth of a meter or one thousandth of a millimeter. Twenty-five microns equal 0.001 inch.
MIL
A unit of measurement equal to 0.001 inch. Often used as a thickness measurement for films, foils, and coatings.
MISTING
The fog sometimes produced during adhesive, coating, or sealer spray application, usually caused by excessive atomizing pressure.
MODULUS
In packaging, used to denote the degree to which a film or sheet resists stretching before it reaches its elastic limit when an external force or stress is applied.
MOIRÉ
An undesired pattern perceptible in the print caused by two or more ink films deposited by printing cylinders prepared without proper screen selection or proper angling of the screen or successive cylinders.
MOISTURE VAPOR TRANSMISSION
The rate at which water vapor will permeate through a film or material. The conditions of the test must be specified for temperature and moisture difference (ASTM E96). See also Water Vapor Transmission Rate.
MONOAXIAL ORIENTATION
The stretching of a plastic film in one direction so as to reduce its thickness and increase its physical properties.
MOTTLE
Nonuniform coloring of a sheet of face material or label. A defect in which the web has a general puckered appearance and will not lay uniformly flat unrestrained.
MOUNT HOPE ROLL
See Bowed Roll.
MSI
Abbreviation for a thousand square inches, a common unit for pricing laminated films.
MVTR
Abbreviation for moisture vapor transmission rate.

 

NANOMETER
A unit of length equal to 10-9 meters (also equal to 10 angstroms).
NATURAL COLORED
The term applied to paper whose color results from the nature of the stock used when no bleach or coloring has been added. In the case of kraft, its natural color is a tan or light brown.
NECK-DOWN
See Neck-in.
NECK-IN
The difference between the width of the extruded coating or web as it leaves the die and the final width. The reduction in width in any web handling process. Also referred to as “neck-down.”
NEEDLES
Very short fine surface scratches which can be oriented in either the longitudinal or transverse direction. They can occur randomly, in repeating patches, or discrete transverse direction repeating bands or stripes. Also see Brushing.
NICKED EDGES
Split or torn film edges.
NIP
The point of contact between two rolls, as in a calendar stack. A two- or three-roller cluster that physically engages for the purpose of isolating web tensions. One or two of them have a braking or drive system and may have elastomeric coverings. The most common setup is a “wringer washer” configuration. The V-shaped gap between a pair of calendar rolls where incoming material is “nipped” and drawn between the rolls. In film blowing, a pair of rolls situated at the top of the tower that closes the blown film envelope, seals air inside of it, and regulates the rate at which the film is pulled away from the extrusion die. One roll is usually covered with resilient material, the other being bare metal with internal cooling means.
NITROCELLULOSE
Any ester of nitric acid and cellulose.
NON-BLOCKING
A term pertaining to an applied adhesive coating that will not adhere to itself and/or other surfaces under normal stacked storage conditions. Also see Block, Blocking.
NON-FLAMMABLE
Will not support combustion.
NON-FOGGING FILM
Film that does not become cloudy from moisture condensation caused by temperature and humidity changes.
NON-ORIENTED FILM (Annealed Film)
Film that has not been subjected to stress to align the polymer chains and improve properties.
NONPOLAR
Having no concentrations of electrical charge on a molecular scale, thus incapable of significant dielectric loss. Examples among resins are polystyrene and polyethylene.
NON-WARP
Refers to a material that does not curl.
NYLON
A strong polyamide plastic that can be used as a film with high oil and gas resistance or as a filament in strapping tapes with high impact resistance.

 

OD
Outside diameter.
OFF-CORE
Layers of tape in correct alignment; but tape is displaced sideways on core.
OFF-GAUGE
Not within specified dimensions of thickness.
OFF-RANGE
Not within specified dimensions of thickness.
OFFSET
Set-off. A defect characterized by the partial transference of ink or coating from a freshly printed or coated surface to an adjacent surface, e.g., another sheet of paper. The accidental transfer of ink or coating from the idler or other rolls in a press to the web.
OFFSET PAPER
A paper designed for use on offset presses, with general characteristics of resistance to distortion from stretching or shrinkage, good pick strength, freedom from fuzz, and a smooth surface, which will take ink evenly without “set-off.”
OFFSET PRINTING
A process of indirect printing in which an impression of type, or a design on a flat plate, is printed on a rubber-blanketed cylinder from which it is impressed, i.e., off-set, upon the surface to be decorated.
OHM
A unit of electrical resistance equal to 1 volt divided by 1 ampere.
OHMS PER SQUARE
Measure of metal deposition by electrical resistance. When measuring resistance across a uniform square of metallized film, the value of ohms is identical whether the sample is 1 inch, 1 foot, or 1 yard square because the width of the current path increases or decreases in exact proportion to the length of the current path. In actual practice, the resistance might be measured lengthwise on a 10-inch length of film that is 0.5-inch wide. Such a sample has 20 squares (10 ¸ 0.5) and the resistance in ohm is divided by 20 to arrive at ohms per square.
OIL SPOT
A surface contaminant which can occur randomly. Often difficult to detect in clear film, the contaminant usually becomes quite apparent after metallizing in the form of clear spots in transmitted light or dark spots in reflected light.
OOZING
A “squeezing out” of material, typically a pressure-sensitive adhesive from between layers. This phenomenon may result in the edges of stacks of sheets or roll form becoming tacky or, in the case of roll die-cut labels, the adhesive adhering to the reverse side of the liner.
OPACITY
Resistance of material or body to transmission of light.
OPAQUE
Not permitting the passage of light.
OPP
Oriented (usually biaxially) polypropylene.
OPTICAL DENSITY
A measure of opacity of a metallized film layer. It is the log of the ratio of the intensity of transmitted light to incident light as 1/log (percent transmission).
OPTICAL DISTORTION
Change in appearance of object when viewed through a transparent material having certain defects, such as waviness of surface, etc.
ORANGE PEEL
A surface appearance defect. Small waves that look like the surface of an orange.
ORIENTATION
A realignment of molecules in a definite pattern by application of an external force to modify characteristics of the original structure.
ORIFICE
In extrusion, the opening in the extruder die formed by the orifice bushing (ring) and mandrel.
OUTGASSING
The evaporation of a volatile substance such as moisture, solvent, or plasticizer from a material. A term used in the vacuum-metallizing industry for the evaporation under vacuum of a volatile substance, which causes loss of vacuum and darkening and poor adhesion of metal coating.
OUTTURN SAMPLES
Samples sent to a customer as representative of the material that will be shipped to him.
OVERCOATING
A coating applied to a web to give gloss and/or protection. In extrusion coating, the practice of extruding a web beyond the edge of the substrate web. Application of a clear film to a substrate (usually preprinted) for the purpose of protection or to enhance graphic quality.
OVERLAP
A simple adhesive joint in which the surface of one adherend extends past the leading edge of another.
OVERLAP SPLICE
The joining of two webs by overlapping their ends, usually with double-sided, pressure-sensitive tape sandwiched between.
OVERLAY SHEET (Surfacing Mat)
A nonwoven fibrous mat used as the top layer in a cloth or mat layup to provide a smoother finish or minimize the appearance of the fibrous pattern.
OVERPRINT
The result of printing one layer over another, such as one layer of ink printed over another one to form color combinations.
OVERTONE
The modifying hue or tone of a color.
OXIDATION
Reaction of any substance with oxygen.
OXYGEN TRANSMISSION RATE
A measure of the amount of oxygen that penetrates a food package or film substrate. The units are typically cubic centimeters per mil per 100 square inches at 24 hours at 1 atmosphere pressure.

 

P1 TEST PROCEDURES
A large body of standard test methods developed or recommended by Technical Committees of Packaging Institute to provide uniform and reliable tests.
PACKAGING, FLEXIBLE
Packaging involving the use of such flexible material as foils, films, paper, etc. to form the container.
PACKAGING, FRACTIONAL
The breaking down of a unit package into two or more sub-units, with the objective of protection of the sub-units.
PAPER, SULFATE
Kraft paper, a chemical wood pulp paper (the strongest pulp paper made from wood).
PAPER, SULFITE
Any type of paper made from pulp produced by the sulfite chemical process. Used in packaging applications where appearance and printability are of primary importance.
PAPER, WAX or WAXED
All papers that have been impregnated, coated or otherwise treated with waxes or waxlike materials.
PAPERBOARD
A heavyweight thick sheet of paper, usually a thickness of 0.06” or over.
PARCHMENT PAPER
A sulfuric acid partially hydrolyzed cellulose fiber converted into a film called vellum, simulating the genuine animal skin product.
PARCHMENT, ARTIFICIAL
Certain greaseproof papers made by wholly physical means, but having no natural wet strength; resembles vegetable parchment.
PARCHMENT, VEGETABLE
A vegetable-base paper having no taste or odor, consisting only of pure cellulose. Highly greaseproof, and outstanding in wet strength.
PATCH HAZE
Cloudy or foggy appearance in a metallized film, usually attributed to a surface condition on the base film.
PE
Abbreviation for polyethylene. Used when someone wants to avoid being specific, but is usually synonymous with low density polyethylene.
PEAKING
The condition that occurs when a nondistensible flat web material is forced to conform to a three-dimensional product, resulting in the excess material gathering and folding into sharp points or “peaks,” thus concentrating stresses at these places and increasing the possibility of fracturing and pin holing. This is a particularly acute problem with recellophaned polyethylene pouches for refrigerated or frozen products.
PEEL ADHESIVE
The force required to break the bond between a tape and the surface to which it is applied. Usually measured by peeling back the tape at 180 degrees (or sometimes at 90 degrees in the case of certain backings) at a standard rate and condition and expressed in ounces per inch width (PSTC Method 1).
PEELING BOND
A type of bond that occurs when two adhered surfaces may be pulled apart without tearing the fibers.
PEEL-SEAL
A package seal made using an adhesive that can readily be peeled open.
PERFORATING
The punching of holes or slits in the web or sheet for separation along the pattern established. Also can serve other functional purposes, such as providing air passage, guide holes, etc.
PERMANENT SET
The change in length or shape with time; no return to original. Often occurs near the core in rollstock.
PERMEABILITY
Ability to be permeated by gases or liquids; a measure of the freedom with which gases or liquids can diffuse through a material.
PET
Polyester film.
pH
Numerical representation of acidity or alkalinity. Neutral is pH 7, pH 1 is extremely acidic and pH 14 extremely alkaline.
PICKING
The lifting of any portion of a paper surface during the printing impression, due sometimes to inadequate surface sizing and sometimes to excessively tacky ink.
PICKOFF
Random or repeating areas in a web where the ink or coating has been removed due to making contact with a roller surface that is contaminated or moving at a different speed.
PICK-UP ROLL
A spreading device where the revolving roll for picking up the adhesive runs in a reservoir of liquid adhesive.
PILE
See Fill-In.
PIMPLES
Sharp-pointed protuberances above the roll surface that can cause indentations (sometimes called “dimples”) in individual overwraps. They can be caused by wound-in particulate contamination or localized poor slippage between film layers.
PINHOLING
In metallized film, very small holes through the thickness of the film which, normally, are not evident until the film is held against a strong light source. In coating, a defect usually attributable to the drying process when evaporating solvent from the depth of the coating penetrates the semidried surface.
PINWINDOW
In metallized film, a very small void in metal coating resulting from a contaminant being on the film surface during the metal deposition process.
PLANARITYSee Flat.
PLASTICIZER
An agent or compound that is added to plastic materials to impart softness or flexibility.
PLASTICIZER MIGRATION
Movement of plasticizer to the surface of a plastic, or from one plastic to another, or from a plasticized substance into the atmosphere; causes embrittlement.
PLASTOMETER
An instrument for determining the flow properties of a thermoplastic resin by forcing the molten resin through a die or orifice of specific size at a specified temperature and pressure.
PLATE
(noun) Curved or cylindrical shape carrying printing impression, for use on a printing press.
PLATEN
A steel plate used to transmit pressure and/or heat in a press, i.e., platen press.
POINT
A measure of thickness of a paper stock or plastic film. One point equals one-thousandth of an inch (.001 inch).
POLISHING ROLL
A roll with a highly polished chrome-plated surface that is utilized to produce a smooth surface on a sheet as it is extruded or in other web operations, i.e. calendering.
POLYESTER FILM
A film produced from polyethylene terephthalate (PET) which is usually biaxially oriented and typically has good resistance to moisture, solvents, oils, and many other chemicals. It is usually transparent.
POLYETHYLENE (PE)
A synthetic polymer derived from ethylene. Typical properties include a low intrinsic surface energy (difficult to obtain ink adhesion without corona or other surface treatments). Available in several density grades, polyethylene offers a range of resistance to solvents, oils, water, and water vapor, as well as many other chemicals. Uses include moisture-resistant packaging and other deformable containers.
POLYLACTIC ACID (PLA)
A biodegradable and bioactive thermoplastic made from renewable resources, typically derived from fermented plant starch (usually from corn). PLA has gained popularity as an environmentally friendly alternative to traditional petroleum-based plastics. In the context of polymer films, PLA is used to manufacture biodegradable and compostable films.
POLYMER
A compound formed by the linking of simple and identical molecules having functional groups that permit their combination to proceed to higher molecular weights under suitable conditions.
POLYOLEFINS
A general term used to describe a family of olefinic materials which includes polyethylene and polypropylene.
POLYPROPYLENE (PPR)
A synthetic thermoplastic material of high molecular weight resulting from polymerization of propylene gas under pressure and heat, plus catalysts.
POLYPROPYLENE (PP)
A synthetic polymer derived from propylene. Typical chemical properties include a low surface energy (requires corona or flame treatment to improve ink adhesion), excellent resistance to solvents, oils, water, and water vapor, as well as many other chemicals. Basic physical properties are similar to polyethylene with polypropylene being a slightly harder polymer.
POLYSTYRENE (PS)
A synthetic polymer derived from styrene (vinyl benzene). Typical chemical properties include a surface energy more compatible with most printing inks, very poor resistance to solvents such as toluene, MEK, benzene, ethyl acetate; good resistance to acids, bases, and lower alkyl alcohols. Polystyrene is typically a fairly rigid, nondeformable, brittle type of polymer.
POLYVINYL BUTYRAL
The reaction product of a partial hydrolysis of polyvinyl acetate with butyraldehyde. The resulting polymer is a tough, flexible material, which is used primarily as the interlayer in laminated safety glass.
POLYVINYL CHLORIDE (PVC)
A tough, hard resin produced from polymerization of vinyl chloride. When plasticized, PVC products have a high elongation and are extremely conformable. They can be used as decal stock, upholstery finishes, pool linings, etc. Unplasticized or slightly plasticized PVC or polyvinyl chloride acetate copolymers are characterized by a high degree of hardness, modulus, and low elongation and are termed rigid. Uses include film, sheet, containers and pipe.
POLYVINYL FLUORIDE
A product of polymerization of vinyl fluoride. Typical properties include excellent resistance to solvents, grease, oil, other staining chemicals, and a very, very low flame propagation rate.
POLYVINYLIDENE CHLORIDE (PVDC)
A product of polymerization of vinylidene chloride. Typical properties include an exceptional resistance to water vapor transmission, excellent barrier to oxygen and carbon dioxide, solvents, greases, oils, etc. Typically used as a coating or as a film lamination in the packaging industry.
POLYVINYLIDENE FLUORIDE
A homopolymer of vinylidene fluoride. It is supplied in powder and pellet form for molding and extrusion and in solution form for casting. The resin has good tensile and compressive strength and high impact strength. Its applications include packaging uses, such as drum linings and protective coatings. It has a high dielectric constant and its film form has unusual piezoelectric and pyroelectric properties.
POROSITY
Of sufficiently loose texture to permit passage of liquid or gases through pores.
POT LIFE
The time period during which an adhesive material remains effective and workable; the time interval before a thermosetting or catalyzed adhesive system begins to gel; the relative resistance of an adhesive material to thickening, foaming, etc., under the stress imposed by adhesive applicator mechanisms.
POUCH, PLICATED
A folded pouch having gussets.
POWDER COATING
The application of a layer of a powder substance to a surface that is then transformed into a continuous coating by heat or some other form of energy. Frequently applied by a fluid bed.
POWER FACTOR
A measure of dielectric loss. Especially important in condenser and cable papers. The power factor is expressed either as a decimal or as a percentage of true power to apparent power. Power Factor =
PPR
Polypropylene.
PREHEAT ROLL
A heated roll installed between the pressure roll and unwind roll whose purpose is to heat the substrate before it is coated or laminated.
PREMASKING
The application of a paper or film to a surface of the substrate prior to printing. Also refers to a paper or film possessing a low tack removable adhesive adhered to a surface to protect said surface during subsequent processing operations.
PRESS POLISH
The finishing of sheet stock or web material, produced by a contact under heat and pressure with a very smooth metal, which gives the plastic or paper a high sheen.
PRESSURE ROLL
The roll which, in conjunction with a backup roll, applies the pressure to a substrate being laminated.
PRESSURE-SENSITIVE ADHESIVE
A permanently tacky, viscoelastic mass, which adheres to a variety of dissimilar surfaces upon contact. As such, a bond may be established without necessity for drying or curing the adhesive mass. Also known as “self-adhesive.”
PRESSURE-SENSITIVE LABELSTOCK
The combination of a face material, pressure-sensitive adhesive, and release liner from which self-adhering labels can be made.
PRESSURE-SENSITIVE TAPE
A combination of a backing material with a pressure-sensitive adhesive.
PRIMED – PRIMING
Coating with a thin layer of adhesive-like material that serves as a bonding agent between the substrate and other materials, i.e., inks, coatings, adhesives, etc.
PRINT THROUGH
The reproduction of foreign matter, i.e. tape and dirt, through multiple layers of roll goods.
PRINTER ROLLER
A roller on a printing press used for application of a uniform deposition of ink on type.
PRINTING COMPENSATOR
A mark printed at regular intervals on the film which actuates a photoelectric cell on the bag machine or wrapping machine to insure the perfect register of copy on a bag or package.
PRINTING, FLEXOGRAPHIC
Formerly called aniline printing. A method of rotary letterpress printing that employs flexible rubber plates and rapid-drying inks.
PRINTING, GRAVURE
A rotary printing process employing minute engraved “wells” in an etched metal cylinder. Deeply etched wells carry more ink than shallower ones, hence print darker values. A doctor blade wipes excess ink from the printing cylinder. Stock is web-fed from roll.
PROFILE
The thickness variation of a web. The statement“’a good profile” describes a fairly “flat” web with minimal point-to-point thickness variation.
PSYCHROMETER
A hygrometer for measuring water vapor in the atmosphere.
PUCKERING
The uneven, nonflat condition in a web material.
PULLDOWN
See Drawdown.
PULLOUT, GOOD
No puckers or banded lanes showing when film is stretched.
PURGE
The act of cleaning an extruder barrel with another type of resin. The removal of moisture from the pumping system of vacuum-metallizing equipment.
PYROMETER
An instrument used to measure surface temperature.

 

QUENCHING
A process of shock cooling thermoplastic materials from the molten state, normally in water.
QUICK SET
To dry and cure rapidly; normally refers to inks.
QUICK STICK
The property of a pressure-sensitive adhesive that allows it to adhere to a surface under very light pressure.
RAILROAD TRACKS
Parallel light and dark lines inmetallizing.
RAZOR SLITTING
The slitting of a web with razor blades. The blades may engage an unsupported web or a web wrapping a grooved backing roller.
REAM
Common unit for surface area of a facing material (such as paper and films). The most widely used surface area in packaging materials and labelstock is 3000 square feet.
REEL
A term applied to the untrimmed roll of web material as removed from the producing machine master roll.
REGENERATED CELLULOSE
A transparent cellulose plastics material made by mixing cellulose xanthate with a diluted sodium hydroxide solution to form a viscose. Regeneration is carried out by extruding the viscose, in sheet form, into an acid bath to create regenerated cellulose.
REGISTER
The exact corresponding placement ofsuccessively printed images and/or successively die-cut pressure-sensitive labels. In multicolor printing, to have such impression in the correct position to ensure that, in each successive pass through the press, the ink deposits are in the correct position on the material being printed.
RELEASE COAT
Coating on a web backing to prevent adhesion and promote easy unwind.
RELEASE COAT TRANSFER
A defect referring to the transfer of the release coat from the backing to the pressure-sensitive adhesive during release.
RELEASE LINER
A paper or film substrate coated with a low surface energy coating (such as silicone), which affords low bonding strength between the coated substrate and an adhesive. This facilitates the handling and processing of composites that contain an adhesive system (pressure-sensitive adhesive), and it is ultimately removed prior to final bonding application.
REMOVABILITY
A relative term applied to pressure-sensitive labels to describe the force or condition under which they can be removed from a substrate.
REMOVABLE ADHESIVE
A pressure-sensitive adhesive characterized by low ultimate adhesion to a wide variety of surfaces.
RESlSTIVITY
The ability of a material to resist passage of electrical current, either through its bulk or on a surface. The unit of volume resistivity is the ohm-centimeter; of surface resistivity, the ohm.
REVERSE PRINTING
Printing on the inside of a transparent film so that the image is viewed through the film; also referred to as second surface or subsurface printing.
REVERSE ROLL COATING
Coating by premetering the substance between rolls whose surfaces are moving in opposite directions and then reverse wiping it off onto the web. The amount of coating is controlled by the metering gap and also by the rotation speed of the coating roll.
REWINDING
To wind again: The operation of winding the web material from the reel or master roll onto a core to produce rolls of desired width, diameter and tension.
RH
Relative humidity.
RIDER ROLL
See Lay-On Roller.
RIDGING
A mound-like swelling on the outer layer of a roll. Usually found on more moisture-sensitive materials (such as cellophane) and caused by variation in film and/or coating thickness.
RIGIDITY
Stiffness; resistance to bending; inflexibility.
ROLL (Roller)
See Anvil Roll, Bowed Roll, Crowned Roller, Dancer Roller, Doctor Roll, Flex Spread Roller, Ironing Roll, Lay-On Roller, Metering Roll, Polishing Roll, Preheat Roll, Pressure Roll, Printer Roller, Skewed Roller, Spreader Roller, Tension Roller.
ROLL FORMATION
The general qualitative appearance of a rolled web. Defects include gauge bands, telescoping, baggy edges. How evenly, smoothly, and regularly film is wound on a roll.
ROLL LABELS
Labels that are packaged in a continuous roll form.
ROLL LEAF
See Hot Stamping.
ROLL SET
The tendency of a web material that has been wound into a roll to retain a permanent set upon unrolling, hence curl perpendicular to the machine direction.
ROLLER COATING (Roll Coatings)
The process of coating substrate with fluid resins, solutions, or dispersions by contacting the substrate with a roller on which fluid material is spread. The process often is used to apply a contrasting color or raised lettering or markings. Also see Kiss Roll Coating and Reverse Roll Coating.
ROPE MARKS
Roll formation defects that look like impressions left by a course braided rope having been tightly wrapped around the roll circumference.
ROTARY BURST SLITTING
The slitting of a web with free-wheeling rotary knives or rotary razors. The knives may engage an unsupported web or a web wrapping a grooved roller.
ROTARY PRESS
A printing press using plates formed to fit rolls and using paper in continuous rolls.
ROTARY SHEAR SLITTING
A slitting method employing a pair of driven rotary shear knives. It produces the best quality slit edge, particularly with thick webs, but is difficult to set up.
ROTOGRAVURE PRINTING
The process of a printing with a thin, quick-drying ink from a cylindrical surface having an etched design. The opposite of letterpress printing, in that the design areas are recessed into the plate instead of being in relief. Also see Gravure Printing.

 

SAGGING
Running or flowing in the finish of a coating caused by the application of excess material and/or by material that is too thin.
SCORE
An impression or a crease to facilitate folding.
SCORE
A slitting method using a rotary knife which “scores” through the web against a smooth metal roller. It is better suited to paper than plastic webs.
SCOUR
Washing and cleaning of fabric for further processing.
SCRATCHES
The linear abrasions in the film surface which can vary in severity. They can be continuous, replicating, or random (i.e., flying scratches). The usual cause is a process roller surface speed not matching web speed.
SCREEN PRINTING
A method of printing in which the ink is forced through the image area of a stretched fabric (synthetic or natural fiber) by the use of a squeegee, or in some cases air pressure, directly onto the substrate to be printed.
SCREENING
An improper print condition occurring when ink fails to flow out between cells, with resulting screen-like patterns of lines or small holes appearing in the print. Usually caused by high ink viscosity or ink drying too rapidly.
SCRIM
A variety of reinforcements that can be used to increase the strength of web materials.
SEA GULLS
A defect in directed gravure coating when a high-solids, pigmented coating is applied while an insufficient flow is present in the coating pan. These defects result from separation of the conveyance and the solids at the point of pickup.
SEALANT LAYER
Specific layer in a packaging material that is designed to provide a secure and effective seal. The sealant layer is crucial in packaging applications where maintaining the freshness, integrity, and protection of the contents are essential. This layer is responsible for creating a hermetic or airtight seal when the packaging is heat-sealed or otherwise sealed during the manufacturing process.
SELF-ADHESIVE
See Pressure-Sensitive Adhesive.
SELF-WOUND
A roll of material with a single liner which is coated on both sides with a release lacquer and a carrier having pressure-sensitive adhesive on both sides.
SERRATED
Saw-toothed. Describes the configuration used on heat-sealing equipment for obtaining a crimp seal. The appearance of a crimp.
SERVICE CONDITIONS
The states of exposure to heat, cold, flexation, impact shock, etc., to which any material will be subjected in use (ASTM D759).
SET-OFF
See Offset.
SHADE OFF
Variation of color in colored film or coatings.
SHAVINGS
The scraps of material that are cut from the sheet or roll in a trimmer, rewinder, or cutter.
SHEAR STRENGTH
The relative resistance of a material to a stress applied in such a manner that the adhered surfaces deform or slide in a plane parallel to their plane of contact.
SHELF-LIFE
The length of time that a container, or a material in a container, remains in a saleable or acceptable condition under specified conditions of storage.
SHOW-THROUGH
In printing, an undesired appearance of printing from the opposite side of the sheet being viewed, due to the translucent character and/or thinness of the sheet.
SIZING
The process of applying a material to a surface to fill pores and reduce the absorption of a subsequently applied adhesive or coating, or to otherwise modify the surface. The material used is sometimes called “size.”
SKEWED ROLLER
A roller that can be easily adjusted in relation to the other fixed transport rollers to aid in web tracking and wrinkle removal. Sometimes called a “squaring roller.”
SLIP
A measure of coefficient of friction (COF). High slip means low COF.
SLIT
To cut a roll of stock to narrower widths.
SLITTER
A machine to cut a roll of stock in the long direction.
SMASH
In flexographic printing, the result of excessive impression of plate to stock or transfer roll to plate characterized by halo effect or double outline.
SMUDGE RESISTANCE
Resistance of a printed surface to ink blurring or smearing; related to the absorption of the substrate.
SOFT FOIL
Fully annealed aluminum foil, commonly referred to as “dead soft.”
SOLAR CONTROL
Reduction of unwanted transmission of solar radiation heat gain through window glazing systems. Typically accomplished via the use of transparent metallized polyester film constructions, either permanently affixed to window glazing systems or hung as a mobile shade.
SOLVENT CASTING
Forming a film by depositing a thin layer of a polymer dissolved or dispersed in solution on a moving, highly polished surface and then evaporating the solvent.
SOLVENT REACTIVATED
An adhesive bonding method in which a resinous adhesive is deposited on one or both adhered surfaces, dried, and then reactivated just prior to bonding by the wiping or deposit of an adhesive solvent on the coated adherend surface.
SOLVENT RETENTION
In packaging materials, the undesirable condition that occurs when the solvent in inks, coatings, and/or adhesives is not completely dissipated.
SOLVENT SEALING
A method of adhering packaging materials which uses small amounts of volatile liquids to soften the coating of the material so it will bond. Examples: cellosolve ethyl lactate, etc.
SPECIFIC GRAVITY
The ratio of the weight of a body to the weight of an equal volume of water at some specified temperature (same as FILM DENSITY).
SPECKING
See Fill-In.
SPLICE
To unite or join the ends of roll material by mechanical or electrical means or by an adhesive.
SPLICE, INCORRECT
Spliced improperly for end use; made using wrong color tape or type of splice.
SPLICE, WEAK
Splices improperly made, of insufficient strength for end use.
SPLIT BACK
Back split; slit back; split liner. Slits in the release liner to facilitate its removal by hand. Slits in the face of a pressure-sensitive product, usually for the purpose of facilitating removal.
SPlTTlNG
In vacuum metallizing, the expelling of particles of molten metal, causing pinholes in the substrate.
SPOKES
Linear striations in roll ends which extend radially from the core. Often symmetrical, those extending to the outer radius can terminate in pimples; in extreme cases, the roll ends can have a “polygon” appearance with transverse flat spots on the roll surface.
SPREAD COATING
See Knife Coating.
SPREADER ROLLER
A special type of roller available in various configurations for the purpose of removing MD wrinkles during web transport via the application of a TD stress.
SPUNBONDING
A sheet web formed by random distribution of very fine continuous fibers that are self-bonded by heat and pressure. No binders, sizers, or fillers are used.
SPUTTER
A high-vacuum coating process in which a high voltage is maintained between a target metal and the substrate to be coated. Inert ions, such as argon, bombard the target metal, freeing atoms that deposit on the substrate to be coated.
SQUARING ROLLER
See Skewed Roller.
STATIC ELECTRICITY
Stationary charges of electricity that sometimes develop in bodies during handling or in machine operations; may cause undesired attraction of film to rollers, flat surfaces, etc.
STATIC ELIMINATOR
A device for removing static charges from a web via grounding or neutralization.
STEEL RULE DIE
A sharp-edged knife used for die cutting.
STENCIL
An application method involving the deposit of a substance in predetermined patterns, applying it through stencil cutouts; a machine component that prints the layer onto the adherend surface in a preselected pattern.
STERILE SEAL
A closure for bacteria-free medical supplies that must maintain sterility.
STERILIZABLE
The ability to withstand contact with steam (moist heat) at 30 lb. pressure for 30 minutes, or contact with dry heat (circulating hot air) at 200°C for 15 minutes.
STIFFNESS
Rigidity, resistance to bending. The degree of stiffness may be measured on a Schopper, Handel-O-Meter, or Curley stiffness testing apparatus.
STRAIN
The amount (in percent of the original length) that a web elongates due to the application of a stress.
STRETCH
Extensibility of materials under tension. Stretch is usually determined in tensile-testing equipment and is recorded as the percentage or extension before the sheet breaks. Normal paper stretch is less than 5%, but by creping, embossing, indenting, and similar processes, up to 30% stretch can be obtained. Stretch of paper also is influenced by the moisture content in the air (see Elongation). Papers processed to ncrease stretch are widely used where molding of paper wraps around complex shapes is desired and in bags and liners for free-flowing products.
STRETCH BANDS
Extreme gauge variation between the edges of the roll.
STRETCH LANES
Same as Stretch Bands.
STRIP PACKAGING
A narrow band of heat-sealed pouches usually films containing small quantities of a product.
STRIPPABLE LABEL
A label that can be removed easily without damaging or leaving material on the surface.
STRIP-PACKAGING
Small articles packaged individually or in multiples in continuous strips, divided in segments or pockets that permit easy tearing off or cutting off.
STRIPPING LINES
See Chatter Marks.
SUBSTRATE
Any material to which adhesives, inks, or coatings are applied, printed, or extruded. Substrates can include film, foil, paper, board, etc.
SUBSURFACE PRINTING
See Reverse Printing.
SUPER CALENDER
A series of rolls operating under high pressure to develop gloss, smoothness, or high paper density.
SURFACE
The electrical resistance between opposite edges of a unit square of insulating material. It is commonly expressed in ohms (ASTM D257).
SURFACE CONTAMINATION
Any liquid contamination on film that will prevent metal adhesion during the metallizing process.
SURFACE PRINTING
Printing on the outside surface of a package as opposed to one of the inside surfaces (see “reverse printing”).
SURFACE WINDING
A method of winding film on rolls in which the winding force is provided by the driven roll in contact with the surface of the winding roll.
SURGING
In extrusion, an unstable pressure buildup leading to variable output and waviness of the surface of the extrudate and thickness variation.
SURLYN
Dupont’s trademark for its line of ionomer resins. Films produced with this resin have excellent seal characteristics such as lower sealing temperatures and excellent hot tack.

 

TABER ABRASION
A method of assessing the abrasion resistance of a material.
TACH-GENERATOR
An electrical device whose output voltage is proportional to an input PRM, i.e., a little generator. Such a device, when coupled to an idling transport roller, can be used to indicate and/or control (via a feedback loop) the web speed.
TACK
In adhesives, commonly regarded as stickiness. Measured as the rate at which an adhesive wets out a bonding surface (PSTC 5 & 6).
TAMPER-EVIDENT LABEL
A destructible label. A construction made to have low strength so that attempted removal of a closure will result in obvious destruction or evident change of the label. Also incorrectly referred to as tamperproof label. The U.S. Food and Drug Administration uses the term “tamper-resistant.”
TAPE TEST
A simple, but effective test for determining the permanency of printing on plastic films or other substrates. A piece of cellophane adhesive tape (“Scotch Tape” or other pressure-sensitive tape) is stuck onto a section of printing or coating, which may be crosshatched, and then pulled off in one motion to see whether the ink or coating will come off with it. The speed and angle of pulling are important.
TAPE, CELLULOSE ACETATE
A translucent, pressure-sensitive adhesive tape of cellulose acetate laminated to strong tissue.
TAPERED TENSION WINDING
A winding method in which the web tension is tapered with increasing roll diameter.
TARNISHPROOF LABEL
A pressure-sensitive label free of substances that will discolor copper or silver.
T-BARS
Discrete linear transverse deviations in flatness. T-Bars or TD (transverse direction) buckles resemble narrow “troughs” which can usually be tensioned out unless they are extremely heavy. Normally caused by improper tension control where the faults are created by cinching or collapsing of voids between film layers when air is expelled from a roll by winding stresses. They normally replicate and are most severe near the core. Also see Buckles and Wrinkles.
TD
Abbreviation for transverse direction, Cross Direction, the direction perpendicular to the machine direction.
T-DIE
Denotes a center-fed, slot extrusion die for film, which, in combination with the die adapter, resembles an inverted T.
TEAR RESISTANCE
The ability of a film to resist tearing or tear propagation after a tear has been started by cutting or nicking the edge. Also see Elmendorf Test (ASTM D1922) and Graves Tear Test (ASTM D1004).
TEAR STRENGTH
The force required to propagate a tear already initiated by a cut on the edge.
TEAR STRIP
A narrow ribbon of film, usually incorporated in the wrapper or overwrap during the wrapping operation, to facilitate opening of the package.
TEAR TAB
An additional area of facestock attached by a release liner to a pressure-sensitive label produced in single form to facilitate removal of the release liner.
TELESCOPING
Transverse slipping of successive winds of a roll or material so that the edge is conical rather than flat.
TEMPER (Aluminum Wire)
It is used for all forms of aluminum alloys. It is based on the sequences of basic treatments used to produce the various tempers. The temper designation follows the alloy designation, the two being separated by a hyphen. Basic temper designation consists of letters such as F for “as fabricated” (no special controls over thermal conditions or strain-hardening are employed during the shaping process), O for “annealed” (treated to obtain the lowest strength temper), and H for “strain-hardened” (strength is increased by strain-hardening with or without supplementary thermal treatments). Subdivisions of the basic tempers, where required, are indicated by one or more digits following the letter. The H designation is always followed by two or more digits, e.g., H18, H16, H14, and H12. These numbers designate specific sequences of basic treatments, but only operations recognized as significantly influencing the characteristics of the product are indicated.
TENDENCY DRIVE
A roller drive system intended to remove any roller rotational and bearing frictional drag, i.e.,a “helper” drive system. Roller surface speed determined by web speed.
TENSILE STRENGTH
Resistance of a material to longitudinal tension. The force parallel to the plane of the specimen required to break a given width and length of material under specified conditions (ASTM D822A). See also Ultimate Tensile Strength.
TENSILIZE
Stretching a web in the machine direction without breaking it to produce internal orientations in the web, improving tensile strength and lowering stretch in the direction of the stretching.
TENSION
The stress caused by a force operating to extend, stretch, or pull apart. The mechanical control of unwinding or rewinding paper, film, foil, and other coil materials.
TENSION ROLLER
A web-transport roller mounted on load cells or a strain gauge for the purpose of sensing web tension.
TENTERING
The process of orienting a web in either the transverse direction or the transverse and machine directions simultaneously.
TEST, CELLOPHANE TAPE
A simple test for determining the permanency of printing on plastic film. A length of pressure sensitive cellophane tape is pressed on a section of printing and then pulled off in one motion to see whether or not the ink lifts with it. The angle and speed of the pulls are important.
TEST, DROP
A package durability test. Filled containers are dropped from controlled heights. A special device insures uniformity of drops.
TEST, DRUM
Rough-handling test for filled container, inside a revolving hexagonal drum.
TEST, ELMENDORF TEAR
A method of testing film for resistance to tearing. The weight required to tear one of several layers of notched film is measured.
TEST, FOLDING ENDURANCE
A test to evaluate the endurance of films to folding, frequently done on a Schopper machine.
TEST, MULLEN
The Mullen is widely used on film packaging materials to determine the relative bursting strength.
THERMOCOUPLE
A bimetallic device to measure temperature electrically.
THERMOFORMING
A method in which heat-softened film or sheet is forced against a cold mold permanently taking on the contours of the mold. Also see Vacuum Forming.
THERMOMETERS
In gravure printing, an extraneous ink film deposited in the shape of a thermometer caused by an ink particle slowly freeing itself from beneath the doctor blade.
THERMOPLASTIC
Capable of being repeatedly softened by heat and hardened by cooling.
THERMOSET
Plastic that is heat set.
THERMOSTAT
An automatic device for regulating temperature; uses bimetallic strip to make and break contacts of electrical circuit.
THERMOWELD
To weld together two or more surfaces of a thermoplastic film material by means of heat.
TIE COATING
One layer of a coating system used to improve the adhesion of adjacent or succeeding coats.
TIE LAYER
The common term for a coextrudable adhesive.
TIN CANNING
A concentration of tension-induced, narrow lines extending around a roll’s circumference. Also known as “machine direction ridges.”
TIR
“Total Indicated Runout,” a measure of roller concentricity.
TISSUE
Lightweight paper, normally 18 pounds per ream or less.
TOP-COATED FILM
Film that has been coated on the surface to be printed to make it receptive to ink. Film that has a protective coating on the surface.
TOTAL INDICATED RUNOUT
See TIR.
TRACKING
The ability of a web to follow a desired path through processing equipment. Follow track without constant adjustment is to TRACK WELL.
TRACKING ROLLER
See Lay-On Roller.
TRANSFER TAPE
A pressure-sensitive adhesive film (unsupported) applied to a two-side release coated liner. Also called “transfer adhesive sandwich.”
TRANSLUCENT
Permitting passage of light, but diffusing it to such a degree that objects cannot be seen clearly; something short of transparent.
TRANSPARENT
Transmitting rays of light so that objects can be clearly seen through the material.
TROLLEY TRACKS
See Railroad Tracks.
TUCK
See Gusset.
TUNNELING
A channel-like delamination pattern in laminated materials, also referred to as “channeling” or “worming.”

 

ULTIMATE TENSILE STRENGTH
The maximum stress that a material is capable of sustaining in tension under a gradual and uniformly applied load.
UNDERFOLD
To fold wrapping material in such a manner that the end folds are turned under the bottom of the package, then sealed to the underside.
UNICELLULAR
With foamed plastics, each cell an isolated unit. Equals “closed cell.”
UNPLASTICIZED VINYL
See Polyvinyl Chloride.
UNWIND ADHESION
The force required to remove the tape from the roll under prescribed conditions.

 

VACUUM DEPOSITION
See Sputter and Vacuum Metallizing.
VACUUM FORMING
A method of sheet forming in which a thermoplastic film or sheet is heated and drawn into a shape by application of a vacuum. Also see Thermoforming.
VACUUM METALLIZING
A semicontinuous process in which the metallic material to be evaporated is heated to a temperature at which its vapor pressure appreciably exceeds the residual vacuum chamber pressure. The substrate is exposed to the metallic vapor stream. The coating vapor impinges on the substrate and condenses to a bright shiny solid.
VAPOR TRANSMISSION
The passage of vapor (usually water vapor) through a material.
VFFS
Abbreviation for vertical form-fill-seal.
VINYL FILM
A tough, durable plastic, polyvinyl chloride (PVC), ranges in properties from rigid (no plasticizers) to very high elongation, highly plasticized (flexible) films.
VISCOSE
A viscous orange-colored liquid obtained by treating cellulose with caustic alkali solution, then with carbon disulfide.
VISCOSITY
That property of a liquid material that tends to resist flow.
VOLATILE
Passing from a liquid into a gaseous state.
VOLATILITY
The rate of evaporation of a solvent.
VOLUME
The electrical resistance between opposite faces of a 1-centimeter cube of insulating material. It is measured under prescribed conditions using a direct current potential after a specified time of electrification. It is commonly expressed in ohm-centimeters (ASTM D257).

 

WARP
See Machine Direction.
WASHBOARD
A more pronounced version of corrugation.
WATER VAPOR PERMEABILITY
The ability of a material to permit transmission of water vapor.
WATER VAPOR TRANSMISSION
A measure of the amount of water that penetrates a food package or film substrate. The units are typically grams per mil per 100 square inches per day. The conventional WVTR test has the water vapor at constant temperature and relative humidity (usually 100 F and 90% RH).
WATERMARK
A translucent marking made in paper while it is still wet for the purpose of identification.
WAVINESS
A warping effect occurring along the edges of roll materials, usually caused by poor slitting technique.
WAX PICK
The ability of the surface of paper to withstand the adhesive powers of a graded set of waxes. The greater the wax number, the greater the pick resistance.
WAX, MICROCRYSTALLINE
A petroleum wax of high molecular weight, characterized by minute crystals and distinguished by its solid wax-like appearance at room temperature.
WEATHEROMETER
Equipment used to measure weatherability by accelerated testing.
WEAVING
A poorly wound roll in which the individual layers are not in alignment with the other layers.
WEB
A term to denote a long film somewhere in the processing stage, frequently being drawn off a large roll. For example, a “printed web” would be a large roll of printed film.
WEB BAG
The condition that exists when the center section of the web droops or sags under tension while the sides are taut. The opposite of Web Sag. Also see Bagginess.
WEB GUIDE
A device that keeps the web traveling straight or true through the process equipment.
WEB SAG
The condition that exists when the sides of the web sag or droop under tension while the center is taut. The opposite of Web Bag.
WEFT
See Cross Direction.
WIRE-WOUND ROD
A small-diameter cylinder wound with a single layer of various diameter piano wire controlling the volume of coating material allowed to pass between the windings. Also see Mayer Rod.
WORMING
In a laminate, lines of delamination caused by excessive tension during winding of an uncured adhesive or by insufficient green tack strength. Also see Tunneling.
WRAP ANGLE
The angle or amount of arc a web forms when traveling around a roller.
WRAP, BUNCH
Wrapping with packaging material gathered on the underside of package in somewhat irregular manner.
WRAP AROUND LABELS
The term “wrap-around labels” does not specifically refer to the material but describes the application and placement of labels on packaging. Labels that are designed to fully encircle or wrap around a product, typically a cylindrical or rounded container, providing 360-degree coverage.
WRINKLES
A very broad term for any typically longitudinal deviations in web flatness, which are usually not a direct result of thickness variations as are stretch lanes. The faults can range from corrugations to sharp foldovers. Causes include poor core starts, roller misalignments, winding tension transients, etc.
WVTR
Abbreviation for water vapor transmission rate.

 

YIELD
Area per unit of weight, usually expressed as square inches per pound.
YIELD STRENGTH
The stress at which a material exhibits a specified permanent set.