ABRASION: The damage caused by friction such as rubbing, scuffing or scratching
ABRASION-RESISTANCE: The ability to withstand the effects of repeated rubbing, scuffing and scratching.
ABSORPTION: The penetration of one substance into the mass of another. (e.g. the absorption of grease or water by Kraft paper.)
ADHERE: To stick together. To cause two surfaces to be held together by adhesion.
ADHERENCE: The quality or state of stocking or adhering. The strength of an adhesive is measured in such a manner that a large part of the loading stress is concentrated at or near the bond to produce apparent fracture in the bond. (See ADHESION)
ADHESION: The act or state of sticking together, uniting or bonding.
AMBIENT CONDITIONS: Surrounding environment. The temperature, humidity, and other condition of the medium surrounding an object.
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.
ANTIOXIDANT: A substance that prevents or reduces oxidation of the material by air or oxygen.
ANILOX ROLL: Engraved ink metering roll used in flexo presses to provide a controlled film of ink to the printing plates which print onto the substrate.
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 bellow-like folds on each side that expand outward when bag is filled.
BAGGY, BAGGINESS: (a) In processing flexible packaging materials, slack areas in the web that should be flat. Usually caused by bands of unequal thickness (gauge bands) in the rollstock. (b) A roll in which the tension is not even across the width of the roll. A slack floppy area in the web is caused by the material being stretched and permanently elongated in the tighter areas. Rolls of film or laminate where one side of the material coming off the roll is loose or baggy while the opposite edge is tight is said to have a baggy edge.
BARRIER: In packaging, this term is most commonly used to describe the ability of a material to stop or retard the passage of atmospheric gases, water vapor, and volatile flavor and aroma ingredients. A barrier material is one that is designed to prevent, to a specified degree, the penetrations of water, oils, water vapor, or certain gases, as desired. Barrier materials may serve to exclude or retain such elements without or within a package.
BIAXIAL ORIENTATION: Orientation of plastic films in both machine and cross machine (transverse) directions by stretching. Biaxial stretched films are generally well balanced in both directions and much stronger in terms of tear strength.
BLEED: Image or color that extends beyond the trim edge of the finished printed piece.
BLOCKING: The undesired adhesion of two or more plies of material, in roll, sheet or package form, to the extent that the surfaces become damaged or distorted, or the ink(s) or coating(s) transfer from one surface to the other when adjacent layers are separated; may be caused by exposure to excessive heat, pressure and/or humidity; in printed film by improper or insufficient drying of inks, resulting in sticking in printed areas.
BON: Biaxially Oriented Nylon.
BOND: (Noun) The attachment to an interface by a laminate. (Verb) To attach materials together by use of a laminate.
BOND STRENGTH: A measure of the strength of the bond between two adherends.
BREAKING 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.
BURT STRENGTH: A measure of the ability of a sheet to resist rupture when pressure is applied to one of its sides by a specified instrument under specified conditions.
CALIPER: (1) An instrument, such as a micrometer, used to measure thickness. (2) Thickness, generally expressed in thousandths of an inch or mills, or in such terms as point, or gauge. One point can mean one mil, but is not specific.
CHIPBOARD: Individual pieces of cardboard that can be placed on one, or both sides of a wicket.
CLARITY: Transparency, freedom from haze.
CO-EXTRUSION (COEX): Simultaneous extrusion of two or more different thermoplastic resins into a sandwich-like film with clearly distinguishable individual layers.
COF (COEFFICIENT OF FRICTION): Coefficient of friction, a measurement of “slipperiness” of plastic films and laminates. Measurements are usually done film surface to film surface. Measurements can be done to other surfaces as well, but not recommended, because COF values can be distorted by variations in surface finishes and contamination on test surface.
COLOR MANAGEMENT: The process of translating specific color information from the computer screen image, through prepress, plate-making, printing presses and finally to a substrate in such a manner that color accuracy is maintained at acceptable levels throughout.
COLOR VALUE: The lightness or darkness of a color. A color may be classified as equivalent to some member of a series of shades ranging from black to white. The other two fundamental characterizers of color are hue and saturation.
COMPATIBILITY: The ability of a container or material to resist chemical degradation or physical change caused by the product, or where a container or material does not chemically degrade or physically change the contained product.
CORONA TREATMENT: A treatment to alter the surface of plastics and other materials to make them more receptive to printing inks.
CURE: (1) To treat a material by the application of time, heat, pressure, chemical agents, or combinations thereof, to impart desired physical characteristics for a specific use. (2) In adhesives, to change the physical properties of an adhesive by chemical reaction, which may be Chemical condensation, polymerization, or vulcanization; usually accomplished by the action of heat and catalyst, alone or in a combination with or without pressure.
CURL: 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.
CUTOFF: In web-fed processing, the cut or print length corresponding to the circumference of the plate cylinder.
DECK: A term used mostly in flexographic printing to describe a single print station with plate, impression cylinders, and inking rolls.
DEGRADATION: A change or break-down in a material’s chemical structure.
DELAMINATION: Separation or splitting of laminate layers caused by lack of or inadequate adhesion, or by mechanical disruption such as peeling or shearing forces.
DENSITY: The mass of a unit volume. Opacity, color, strength.
DIE CUT HANDLE BAG: Poly bags with a large hole at the top of the bag that is used to carry the bag. Handles can be reinforced.
DIRECTIONALITY: The tendency for certain materials to have properties imparted by the flow direction through a machine.
DOCTOR BLADE: A thin flexible blade mounted parallel to and adjustable against an engraved roll, for the purpose of removing (by crimping action) excess material.
DOT GAIN: A physical and/or optical measurement and theoretical calculation of the apparent increase in dot area from one medium to another. Normally expressed as the difference between a mid tone (nominal 50%) dot area on a film negative and the printed dot area; for example, a 50% film dot area which prints as a 78% dot has 28% dot gain. Dot gain (and loss) are normal and must be controlled throughout the press and printing process.
DOWNGAUGE: Use a thinner film than had been previously used.
DRAWDOWN: A swatch of color or coating made by spreading a small amount of ink or varnish across a sheet of material. Made for visual comparison to a standard color swatch or chip.
DWELL TIME: Time that material is in the drying tunnel.
ELASTICITY: The property of a substance which enables it to return to its original shape and size after removal of a deforming force.
EXTRUSION: The process of forming a thermoplastic film, container, or profile by forcing the polymer melt through a shaped orifice.
EXTRUSION LAMINATION: A laminating process in which individual layers of multi-layer packaging materials are laminated to each other by extruding a thin layer of molten synthetic resin (such as polyethylene) between the layers.
EYE MARK REGISTER: A printed rectangular mark most often found along the edge of roll stock that can be identified by an electric eye. The mark identifies a point on the web where an individual package is to be cut.
FILM: Generally used to describe a thin plastic material usually not more than 75 micrometers (0.003 inch) thick.
FINISHING: Any final operation done to packaging before shipping.
FIN SEAL: Seal that results when edges of two superimposed sheets are bonded, resulting in a pouch having fin-like protuberances.
FLEXIBLE PACKAGING: A package or container made of flexible or easily yielding materials that, when filled and closed, can be readily changed in shape. A term normally applied to bags, pouches, or wraps made of materials ranging in thickness from 13 to 75 micrometers (0.0b0á to 0.003 inch) such as paper, plastic film, foil, or combinations of these.
FLEXOGRAPHIC PRINTING: A method of printing using flexible rubber or photo polymer printing plates in which the image to be printed stands out in relief. Fluid ink metered by an engraved roll is applied to the raised portions of the printing plate and then transferred to the substrate.
FORM-FILL-SEAL (FFS): A packaging machine that forms, fills, closes and seals a package in one continuous or intermittent-motion operation. Flexible packaging stock fed from a roll is folded to the desired package shape and stabilized by heat sealing. The product iplaced into the formed package, and the remaining opening is sealed. Machines can be configured so that the stock travels horizontally through the machine (horizontal form-fill-seal) or vertically through the machine (vertical form-fill seal).
FOUR-COLOR PROCESS: Printing with cyan, yellow, magenta, and black ink (CMYK) using halftone screens to create a full color reproduction.
GAUGE BAND: A thickness irregularity found in rolls of film. A thicker area in the machine direction at some location across the width of a flat film will produce a raised ring in a finished roll. Gauge bands can cause winding problems and when unwound, the material tends not to be perfectly flat.
GAUGE: Thickness. In North America, film thickness, measured in mils, is usually given in gauges. A 100 gauge shrink film is one mil, or 1/1000 of an inch, thick. In Europe, the film thickness metric is the micron. A quick equivalency equation is: 1 mil = 25.4 microns.
GEL: A jelly-like material formed by coagulation of a colloidal liquid.
GHOSTING: In printing, transfer of the design image from printed to unprinted areas which may occur between any two adjacent surfaces without actual ink transfer
GLOSS: (1) A term used to express the shine, sheen or luster of the dried film. If a surface clearly and plainly reflects an image of light, it has a high gloss. (2) Absence –of-bloom gloss is indicated by freedom from haziness bordering a highlight. (3) Contrast gloss is expressed as a fraction whose denominator is the apparent-reflectance of the sample when illuminated in a direction other than perpendicular and viewed in the direction of specular reflection, and whose numerator is the same apparent-reflectance diminished by the apparent-reflectance of the sample identically illuminated but viewed perpendicularly.
GOOD MANUFACTURING PRACTICE (GMP): Good manufacturing practice implies that the entire manufacturing procedure has been designed in such a way as to produce a quality product that presents a minimum risk to the consumer. GMP will vary from industry to industry depending on the nature of the product being packaged. Many GMPs have been formalized and are required by law for critical industries such as food and pharmaceutical packaging. Typically these GMPs describe the kind of equipment to be used, its validation, manufacturing procedures, inspection types and frequencies, record keeping, container types and approvals, and registration of company and product.
GUSSET: The fold in the side or bottom of the pouch, allowing it to expand when contents are inserted
HAZE: A cloudy or foggy appearance in a normally clear transparent material.
HDPE: Abbreviation for high density polyethylene. Has much higher stiffness, higher temperature resistance and much better water vapor barrier properties than LDPE, but it is considerably hazier.
HEAT-SEAL LAYER: A heat sealable innermost layer in plastic packaging films and laminates. Can be either adhesive laminated or extrusion coated onto a non-sealable film (or foil).
HEAT-SEAL STRENGTH: Strength of heat-seal measured after the seal is cooled, (not to be confused with “hot tack”, see next item).
HERMETIC: Airtight or impervious to air or fluids.
HERMETIC SEAL: Airtight or impervious to gases or fluids under normal conditions of handling and storage.
HIGH BARRIER: Describes a material or package that has very low gas permeability characteristics; that is, it offers a great deal of resistance to the passage of a gas through its volume.
HOT TACK: Strength of heat seal measured before the seal is cooled, which is very important for high-speed packaging operations.
IMPULSE SEALER: Also known as a heat sealer. These units use an electrical current passed through a Ni-Chrome wire heating element to seal bags & tubing. Can be used on many plastic materials to create strong permanent welds.
LAMINATE: (a) noun A product made by bonding together two or more layers of material. (b) verb To unite layers of material to produce a multilayer material.
LAMINATED FILM: An adhered combination of two or more films or sheets made to improve overall characteristics. Also multilayer film.
LAP SEAL: A seal made with two layers of film overlapping one another. Because lap seals require less material than fin seals, packagers are converting to lap seals in the name of sustainability, lean operations and
LDPE Abbreviation for low density polyethylene. Used mainly for heat-seal ability and bulk in packaging.
LIGHT RESISTANCE: The ability of material to withstand exposure to light (usually sunlight or the ultraviolet part of the light spectrum) without change of color or loss of physical and/or chemical properties.
LIP: That part of the tube of a flat or square bag, or pouch, extending beyond the face of the bag.
LLDPE: Linear low density polyethylene. Tougher than LDPE and has better heat-seal strength, but has higher haze.
LOOSE WIND: Rewind made loosely with insufficient tension, often resulting in “Telescoping”.
MACHINABILITY: The ability of a film to run on packaging equipment.
MACHINE DIRECTION (MD): The direction that film moves through the packaging equipment.
MANUFACTURING TOLERANCE: Permissible variations from rated or marked capacities or dimensions established by standards or specifications for those.
MDPE: Medium density, (0.934-0.95) polyethylene. Has higher stiffness, higher melting point and better water vapor barrier properties.
METALLIZE: Applying a thin coating of metal to a nonmetallic surface by chemical deposition or by exposing the surface to vaporized metal in a vacuum chamber.
MET-OPP: Metallized OPP film. It has all the good properties of OPP film, plus much improved oxygen and water vapor barrier properties, (but not as good as MET-PET).
MET-PET: Metallized PET film. It has all the good properties of PET film, plus much improved oxygen and water vapor barrier properties. However, it is not transparent.
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.
MD: Abbreviation for machine direction.
METALLIZING: The process of applying an extremely thin metal coating to a non-metallic substrate.
MIL: A unit of linear measurement, equivalent to 0.001 inch.
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.
MOISTURE-VAPOR TRANSMISSION RATE (MVTR): A depreciated term, usually measured at 100% relative humidity, expressed in grams/100 square inches/24 hours, (or grams/square meter/24 Hrs.) See WVTR.
NYLON: Polyamide resins, with very high melting points, excellent clarity and stiffness. Two types are used for films – nylon-6 and nylon-66. The latter has much higher melt temperature, thus better temperature resistance, but the former is easier to process, and it is cheaper. Both have good oxygen and aroma barrier properties, but they are poor barriers to water vapor.
OD: Outside diameter.
OFF-CUT: Trim that is not utilized. In flexible packaging, a narrow roll of material left over when a material order does not call for the full roll width. Sometimes called a butt roll.
OPACITY: Resistance of a material or body to transmission of light.
OPAQUE: Not permitting the passage of light.
OPP: Oriented PP (polypropylene) film. A stiff, high clarity film, but not heat sealable. Usually combined with other films, (such as LDPE) for heatsealability. Can be coated with PVDC (polyvinylidene chloride), or metalized for much improved barrier properties.
OPTICS: The visual properties of a film, such as clarity, gloss, haze, opacity, etc.
ORIENTATION: The process of mechanically stretching plastic film or parts in order to produce a straightening and alignment of the molecules in the stretch direction. If done in one direction, the material is said to be uniaxial or monoaxially oriented. If done in two directions, the film is biaxially oriented.
OTR: Oxygen transmission rate. Varies considerably with humidity, therefore it needs to be specified. Standard conditions of testing are 0, 60 or 100% relative humidity. Units are cc/100 square inches/24 hours (or cc/square meter/24 Hrs). (cc = cubic centimeters)
PASS: One trip of a material through a production machine or manufacturing step.
PILLOW POUCH: A bag or pouch in the form of a tube that is sealed at both ends. Pillow type pouches are most commonly produced on vertical-form-fill-seal (VFFS) machines and are characterized by seals across the top and bottom, and a longitudinal seal going down the center of one of the faces.
PLATE BREAK: Non-print area where the two ends of flexo plate butt together after being wrapped around the plate cylinder on the printing press.
PMS NUMBER: The Pantone Matching System is the universally accepted color definition system. Colors can be blended or individually specified to match a specified Pantone reference color exactly.
POLYETHYLENE FILM (PE): Polyethylene film is by far the largest volume packaging film family, and is available in high density, low density, linear low density, and metallocene variations.
POLYETHYLENE TEREPHTALATE FILM(PET): Polyester, (Polyethylene Terephtalate). Tough, temperature resistant polymer. Biaxial oriented PET film is used in laminates for packaging, where it provides strength, stiffness and temperature resistance. It is usually combined with other films for heat sealability and improved barrier properties.
POLYPROPYLENE FILM (PP): Unoriented film is soft and clear but brittle at low temperatures. This property as well as stiffness, strength and clarity is improved by orientation.
POUCH: A small bag usually constructed by sealing one or two flat sheets along the edges. There is no clear distinction between a pouch and a sachet other than the common understanding that a sachet is smaller.
PRIMER COAT: A coating applied over a substrate for the purpose of improving an ink or adhesive bond.
PROCESS COLOR: Color printing created by separating the copy into the primary colors to produce individual halftones of each color, that are recombined at the press to produce the complete range of colors of the original. Process printed photographic reproduction would normally be done with cyan, magenta, yellow and black (CMYK) inks.
PVDC: Polyvinylidene chloride. A very good oxygen and water vapor barrier, but not extricable, therefore it is found primarily as a coating to improve barrier properties of other plastic films, (such as OPP and PET) for packaging. PVDC coated and ’saran‘ coated are the same.
REGISTER: Exact alignment of one part or operation with another part or operation.
REVERSE PRINTING: Printing wrong-reading on the underside of transparent film. In this case, the outermost layer is printed on the backside and laminated to the rest of the multi-layer structure. While not mandatory in all industries, it is the preferred method for the food industry as it guarantees there will be no ink contact with the food product. The majority of all products are reverse printed.
REWIND: To wind again; especially the winding of a roll of film after printing, slitting, etc.
ROLL STOCK: Said of any flexible packaging material that is in a roll form.
SEALABILITY: That property of a material which renders it capable of being sealed.
SLIP: The ability of film to move easily over hard plastic, metal, or ceramic platforms or against another piece of film.
SLITTING: The conversion of a given width of a film or sheet material into narrower widths. Web stock is unrolled past a series of knives set to the correct widths, and the slit web is rewound back into roll form.
SLITTER: A machine to cut a roll of stock in the long direction.
SPLICE: Joining two pieces of web material to form a continuous web.
SPOT COLOR: Solid colors not created by using screens. Usually a Pantone Matching System (PMS) color.
STAND UP POUCH: A flexible pouch design where the bottom portion has been gusseted in such a way that that it provides a wide enough base to provide support so the pouch is able to be stood up for display or use.
STICK PACK: A narrow flexible packaging pouch commonly used to package single-serve powder beverage mixes such as fruit drinks, instant coffee and tea and sugar and creamer products.
STICKYBACK: Double-faced adhesive-coated material used for mounting elastomeric printing plates to the plate cylinder.
STIFFNESS: Rigidity; resistance to bending.
STRENGTH: The mechanical properties of a material which permit it to withstand parting or distortion under the application of force. Strength properties include toughness, tensile strength, flexural strength, tear strength, flexibility, etc.
SURFACE PRINT: The process whereby the ink is deposited directly onto the outermost surface of the packaging film or material. The process is most commonly used in short run printing. A UV (ultraviolet) coating may be added to provide a hard exterior finish that prevents the ink from flaking or chipping.
TEAR RESISTANCE: The ability of a film to resist the propagation of a tear.
TENSILE STRENGTH: The amount of pull a film can withstand without tearing apart or stretching.
THREADING: The placing of a web material through the various rolls and stations of any web-fed press such as a printer or laminator in preparation for production.
THREE-SIDE SEAL POUCH: A pouch that is formed by folding the web material into a U-shape and then sealing the three open sides. The pouch may be made with a gusseted bottom. Three-side-seal pouches are typically made on horizontal form-fill-seal machines.
TOLERANCE: Permissible maximum deviation from specified dimensions or qualities.
TIE LAYER: A material that bonds two incompatible layers in a coextrusion.
TRANSVERSE DIRECTION (TD): The direction perpendicular to the machine direction.
TRACKING: A film that follows a desire path on a packaging machine without constant adjustment is said to “track” well.
TRAPPING: In printing, inks may be overlapped slightly by increasing the image size to ensure that no substrate shows through within the register variations of the printing press.
TRIM: (1) (Verb) To cut away excess or imperfect material, as uneven edges, sheet not removed in blanking operations, etc. (2) (Noun) The excess material thus cut away
TUNNELING: A laminating defect caused by incomplete bonding of the substrates.
VAPOR BARRIER: A layer of material through which water vapor will pass only slowly, or not at all.
VOID: An emptiness or absence of a substance. For example, an area of coated film that is not coated.
WATER VAPOR TRANSMISSION RATE (WVTR): A measure of the rate of water vapor transmission through a material. Usually measured at 100% relative humidity, expressed in grams/100 square inches/24 hours, (or grams/square meter/24 Hrs.) See MVTR.
WEB: A continuous length of paper film, foil, or other flexible material as it is unwound from a roll and passed through a machine.
ZIPPER POUCH: A flexible plastic pouch with a molded-in-place sealing device wherein a projecting rib or fin is inserted into a mating channel to effect a closure. A zipper seal can be repeatedly opened and close