Food Packaging & Printing Glossary

 
Listed below are brief definitions of terms commonly used in the packaging and printing industries.

2P: Aluminum cans are 2P (two piece) cans, comprising a top and body. The body is formed from a sheet of aluminum and drawn to the required height, decorated in the round (up to six colors) and coated internally. The customer adds the top (second piece) after filling.

3P: Steel cans are 3P (three-piece) cans comprising a top, a body and an end (base). The body is formed into a cylinder from a sheet of pre-printed or plain tin-coated steel and the end is seamed to it prior to delivery to the filler. The customer adds the top (third piece) after filling.

Absorbent Packing: Material within a package which absorbs liquids from product, i.e. pad in meat trays is made from paper and has a plastic liner.

Aseptic Packaging: A technique for creating a shelf-stable container by placing a commercially sterile product into a commercially sterile container in a commercially sterile environment. The sealed container is designed to maintain product sterility until the seal is broken.

Anilox: An ink roller used to control the amount of ink transferred onto substrate during line screen printing. Anilox rollers are often referred to by the number of lines, or divots, on the roll. Higher line counts mean smaller divots, which transfer less ink onto the substrate.

Back Seams/Seals: A seal in a bag which runs down the middle of the back, in machine direction. Many back seams such as fin seals and lap seals are made by form fill and seal machines.

• Fin seals are created when the inside edges of the substrate are bonded, leaving the seam standing out from the package, such as on potato chip bags.
• Lap seals are made when two layers of substrate overlap, forming a bond with no material standing out from the package.

Bacon Wrapper Paper: A glassine, greaseproof, or vegetable parchment paper, or a laminated product made from these papers and other materials, used for wrapping bacon.

Blister Packaging: The item is secured between a preformed, usually transparent plastic, dome or bubble and a paperboard surface or carrier; also referred to as a “bubble pack”, i.e. bologna package hanging on a peg in a supermarket’s refrigerated case.

Boil-in-bag: A sealed container made of heat-resistant material designed to hold a food product and permit the ultimate user to bring the bag and product to boiling temperature in preparation for eating before the product is removed from the bag, i.e. frozen entrees or vegetables.

Breathing/Breathable Package: Packaging material made in such a manner that air may enter or leave under varying conditions, including temperature changes, with or without a drying agent to remove moisture from entering the package. Most wrap used for fresh red meat allows enough air to pass through to keep the proper color in the meat.

Blow Molding: Formation of a bottle from a molten plastic tube by blowing air into the mass, forcing the material to follow the shape of the mold.

Bond Strength/Seal Strength: A lamination term referring to the integrity of a connection between 2 or 3 materials glued together. Also known as a “destruct bond” where the strength means the materials will break before the seam does.

Bottom Seal: A bond between two layers of polyethylene made by a heated bar (element) which does not separate the bag from the roll. The placement of this seal is determined by the machine and printing direction. Bottom sealed bags are separated by a guillotine type knife which leaves one half inch of unsealed material at the bottom of the bag.

Broke: Paper trimmings, paper damaged due to breaks on a paper machine or not manufactured to the required quality specification. Broke is usually fed back into the paper manufacturing process.

Can: A receptacle generally having less than 10 gallon capacity, consumer or institutional sizes; also means to pack a product in a can or a wide-mouth glass container for processing, shipping or storage.

CAP (Controlled Atmosphere Packaging): A packaging method in which selected atmospheric concentrations of gases are maintained throughout storage in order to extend product shelf life. Gas may either be evacuated or introduced to achieve the desired atmosphere. Normally used for fruits and vegetables, not meat products.

Cardboard: Term erroneously used for “paperboard”, it is a stiff, moderately thick paperboard, heavier than paper, i.e. used for frozen entrees.

Carton Dimensions: Dimensions refer to the interior of a carton, measured in millimeters of Length x Width x Height. Length (L) is the longer side of the opening and Width (W) is the shorter. Height (H) is the length between the openings on either end.

Cellulose: The main fibrous material in paper.

CPET (Crystallized Polyethylene Terephthalate): A heat-tolerant plastic that can be molded into multi-compartment and single frozen food containers; can be heated in the microwave or conventional oven.

Closures: Closures are caps or lids used to seal beer, soft drink bottles, food jars, and cans. Closures are made from plastic, steel or aluminum and can be screw, twist or pop-up style. Another type of closure is a plastic seal, which is used to reseal a metal can after opening. ‘Closures’ also refers to machinery used to apply the closures to containers after they are filled.

Composite Cans: Cans made from paperboard. A variety of barrier materials and fittings enable composite cans to be used for packaging food, powdered beverages, wine, spirits, and perfume.

Core: The paper core, with a diameter between 3 and 6 inches, on which bags or packaging material is wound during manufacture.

Corrugated Fiberboard: This material refers to the composite structure formed by gluing one or more sheets of fluted, corrugated material to one or more flat facings of linerboard.

• Single-wall carton: This is a corrugated fiberboard carton made by gluing a sheet of fluted corrugated material between two flat sheets of linerboard.
• Double-wall carton: This is a corrugated fiberboard carton made of three sheets of linerboard interleaved with two sheets of fluted corrugated material.

Crimp Seal: A sealing process which uses scribed heating elements to bond substrates, such as the end seals of potato chip bags.

Cylinder: The machined rollers on which printing plates are mounted for use in a CMF printing press.

Delicatessen Paper: Used as an inner wrap for meats and for soft foods to retain the moisture in the food and to prevent the outer wrapper from becoming water- or grease-soaked; made from bleached chemical wood pulp and may be given a dry paraffin wax treatment of about 10 to 20 percent of the weight of the paper.

Die Cutting: The process of cutting a corrugated sheet into a shape which will convert to the required box size when assembled. A rotary die cutter uses a cylindrical die and is generally capable of higher speed than a flatbed die cutter, as the sheet flow basically continues. A flatbed die cutter uses a flat die and the corrugated sheet momentarily stops to enable the required cutting. This method provides both high accuracy and intricate shapes not available from the rotary process.

Double-facer: A double-facer, or double-backer, is the part of a corrugator which bonds single-face board to another liner to produce a double-faced corrugated sheet.

Eyemark: These small, black lines are usually made on the edge of the substrate, repeating throughout the length of the roll precisely in the same spot in relation to the printed design. Eyemarks are detected by a photocell on the machine, to indicate when a task is required. Eyemark placement must be consistent for processing machines to produce the best results.

Fiberboard Can: A rigid container constructed almost completely of lightweight fiber stock; may be lined, treated or coated; ends of can may be made of paperboard or metal, composite can, i.e. packaging used for juice concentrates, potato sticks and onion rings.

Flavor and Aroma Barrier: The ability of a substrate material to act as a barrier to flavor and aromas, often linked to its OTR (Oxygen Transfer Rate).

Flute or Corrugation: This refers to the wave shapes, or ridges, that are pressed into a sheet of material that has been softened by steam. This material is then sandwiched between flat sheets of material to form corrugated fiberboard. Flute serves as protective cushioning and helps strengthen a carton. Different widths and configurations offer distinctive performance advantages. Corrugated cartons feature either of the types below.

• A-Flute: Flute thickness of 4.7 mm
• B-Flute: Flute thickness of 2.5 mm
• C-Flute: Flute thickness of 3.6 mm Depending upon the stacking strength, puncture resistance, or crush strength required for the carton, one of the above three commonly corrugations are used in single-wall, general-purpose cartons. A-Flute has excellent stacking Strength, B-Flute has good puncture resistance, and C-Flute has the optimum combination of both.
• E-Flute: Flute thickness of 1.5 mm, it is generally used for light applications, i.e. pizza boxes, mailers, and shoe boxes.
• BC Flute: This flute is a double-wall combination made from one B-flute, single-wall sheet and one C-flute, single-wall sheet. The result is a strong corrugation used when extra thickness or stacking strength is needed.
• AC Flute: This flute is a double-wall combination made from one A-flute, single-wall sheet and one C-flute, single-wall sheet. The result is a very strong corrugation used when extra strength is needed.

Flexible Packaging: Bags, envelopes, pouches or wraps which can be changed in shape or bent manually; made of materials such as paper, plastic film, foils, etc., or combinations of them. This covers a wide range of packaging that can be single and multi-layered, and is supplied in reels or bags. It can be paper, poly, foil, or nylon, or a combination of materials which are supplied either plain, printed, coated, and/or laminated to provide long shelf-life properties. End products packaged include confectionery, snack foods, frozen foods, soups and pharmaceuticals.

Foam Trays and Other Foam Shapes: Made from EPS (expanded polystyrene); formed when foaming agents are added to polystyrene and passed through a die, i.e. trays for fresh meat and egg cartons. Styrofoam™ is an insulation used in building materials and is not used in packaging.

Folding Cartons: Multi-layer paperboard cartons which are printed/coated and cut into carton blanks. The carton blanks also incorporate creases, which enable the carton to be formed for packaging products.

Form Fill and Seal Machine: Machines usually purchased by food producers to facilitate product packaging by creating packages and filling them with product in one step. FFS machines can be oriented either vertically (VFFS) or horizontally (HFFS). Vertical machines form and cut packages, to be filled with product dropped into the package before final sealing. Horizontal machines are used in cases where dropping a product vertically may cause damage (such as pastries, chocolate bars and cookies) and instead, the product is placed into the package horizontally.

Frozen Foods Paper: A type of high moisture and water vapor resistant paper used for inner liners in frozen food packaging, usually specially treated glassine or bleached chemical wood papers, waxed papers, or plain or coated vegetable parchment paper; pliable and strong to resist cracking at freezing temperatures and for high wet strength.

Functional Coatings: The lamination of polyethylene, plastic, or foil films to paper substrates, providing a water or greaseproof barrier. Typically used in high humidity applications in both tropical and cold temperatures, for use with meat, seafood, pet food, fruit, and produce.

Gas Flush: A procedure used in food packaging where gas is used during the packing process to evacuate oxygen and moisture before the package is sealed.

Gauge – Mil: Interchangeable terms referring to the thickness of a substrate material.

Glassine: Smooth, dense, transparent or semi-transparent paper manufactured primarily from chemical wood pulps; is grease resistant and has a high resistance to the passage of air. It may be waxed, lacquered, or laminated to be impervious to the transmission of moisture vapor, and can be white and other colors.

Gravure Printing: This printing medium is the transfer of ink from an etched cylinder, such as a sunken surface, to the substrate, eg. Paper, film, or foil. The equipment is a multi-station printing machine to print and/or coat multiple colors/coatings, typically up to eight colors/coatings, on to a fast-moving web of material.

HDPE: High-density polyethylene.

Injection Molding: The process of converting plastic pellets by using heat and pressure to inject the molten material into a water-cooled mold. The equipment can produce a number of products in the one injection.

Impression: This can either refer to the amount of pressure used to place ink on a substrate or, more commonly, the measurement of the overall area used to print a design on a substrate.

Kraft: This term describes the natural, unbleached corrugated fiberboard used in making cartons.

LBS/M or LBS Per Thousand: Describes the weight of material used to make 1000 impressions on a given material.

LDPE: Low density polyethylene.

Linerboards: Linerboards form the inner and outer facings of corrugated fiber boxes and are chosen for their structural and/or decorative properties. They can be made from white or brown, Kraft or recycled fibers, or a blend of both.

Line Printing – Spot Printing: Image printing using a set of premixed inks for each color required in the design. This is also referred to as screened print.

Line Screen: A count used to describe the concentration of dots in an image over a specific area, such as DPI (dots per inch). A higher line screen count results in a higher quality image.

Lineal Ft.: Refers to the number of feet unwound from a roll of substrate, measured along the length of the unrolled material.

Machine Direction: Describes the direction a film travels through a machine during processing, often used to decide the direction an image is printed on the film, and where cuts and seals are to be made.

MAP (Modified Atmosphere Packaging): A packaging method in which a combination of gases such as oxygen, carbon dioxide, and nitrogen are introduced into the package at the time of closure, the purpose of which is to extend shelf-life of the packaged product , i.e. lunch meat in a blister package.

Meat Wrapping Paper: A specially treated odorless and tasteless paper that resists meat juices, fat, and grease, and is easy to remove from any kind of meat.

Mechanical Pulp: Pulp produced by reducing pulpwood logs and chips into their fiber components by the use of mechanical energy, via grinding stones or refiners.

Metal Can: A rigid metal container made of steel sheet or plate, 27-gauge or less in thickness, or a similar container made of aluminum, copper, or other metal, i.e. food cans.

Metalising: Applying, through a vacuum process, a thin aluminum layer onto flexible plastic film substrates used to package a variety of foods.

Migration: Transfer of a component of a packaging material into the product contained, or loss of a component of the product into the packaging material.

Netting (Plastic): Continuous extruded net of flexible plastic material, most commonly polyethylene, which can be made into bags, sleeves, or wraps, i.e. net over a frozen turkey package.

Nylon: Nylon is a versatile family of thermoplastic resins that vary from relatively flexible products to tough, strong and stiff materials; resistant to oils and greases; widely used for meat and cheese packaging, for boil-in-bags and pouches.

OD (Outer Dimension), ID (Inner Dimension): Terms often used to describe either the size of a roll’s core, or the size of the complete roll. ID commonly refers to the inside measurement of a package, either with or without the width of the seals included.

Offset/Lithographic Printing: This printing medium is the transfer of ink from a sensitized plate, offset to a rubber blanket and then transferred to the substrate. The equipment is a multi-station, typically up to eight, printing machine to print and/or coat up to six colors on to sheets or a fast-moving web.

OPP, BOPP, CPP:

• OPP (Oriented Polypropylene): A term used to describe polypropylene which is stretched in machine direction, creating properties desirable in certain food processing situations.
• BOPP (Biaxially Oriented Polypropylene): Material which has been stretched in both machine and transverse direction, creating properties desirable in certain food processing situations.
• CPP (Cast Polypropylene): Inexpensive, un-stretched material with very limited barrier qualities, not often used for food packaging.

OTR (Oxygen Transfer Rate): Describes a material’s barrier abilities against oxygen. This is particularly important to food packaging, as oxygen can damage oil and far molecules, decreasing shelf life of a product.

Ovenable Board: A paperboard that can be placed in an oven, microwave or conventional, to serve as the cooking vessel for food, typically a solid, bleached sulphate board coated with polyester terephthalate, i.e. frozen entrees.

Pasting: Two, three or four plies of paper and paperboard are glued together to form a solid fiberboard with a thickness ranging between 0.8mm to 3mm. The boards are used for a variety of applications such as shoe boxes, screen printing, display boxes, board games, book covers, and ring binders.

PE: Polyethylene, a low cost soft flexible material often used as an outer wrap. PE is also used as a sealant layer for laminates, due to its ability to create hermetic seals.

PET: Any substrate made of polyester, without coatings.

PET, Coated: Polyester substrate coated with PVDC to increase the film’s resistance to oxygen and moisture.

PET, Met Pet: Polyester substrate coated with aluminum on one site. In addition to oxygen and moisture barrier, this coating provides protection against UV (ultraviolet) light, which can damage oil or fat molecules. Met Pet is commonly used in food packaging.

Plasticizer: Material added during the manufacturing process to increase flexibility; for example, the plasticizer ATBC (acetyl tributyl citrate), used in such DowBrands™ as Saran™ and Handiwrap™, is made from citric acid which is commonly present in citrus fruit.

Polyester, Thermoset: Filled plastic which is heated to harden into a shape and does not soften when heated during normal cooking temperatures, i.e. plastic dishes in frozen dinner entrees which can be heated in the microwave or conventional oven.

Polyethylene Film: The most used transparent flexible packaging material made from polyethylene, a synthetic clear compound formed by subjecting ethylene, a gas found in coal, to pressure. It is low cost, transparent, tough, heat sealable, moisture-proof, and resistant to low temperatures.

Polypropylene: A synthetic resin plastic packaging material used for microwave-only heating of foods with low fat and sugar content; not heat stable for use in conventional ovens.

Polyvinylidene Chloride: A thermoplastic polymer which can withstand higher temperatures than polyethylene, especially useful for covering cooking vessels when microwaving foods, moisture-proof and transparent, ie. Saran Wrap™.

Process Printing: A type of printing used to create photographic quality images by combining four primary inks: Cyan, Magenta, Yellow and Black. Also known as CMYK printing.

Pulp: Primary raw material from which paper is made. A fibrous product produced by mechanical or chemical processes, or a combination of both.

PVC (Polyvinyl Chloride): Replaced cellophane as the preferred meat wrapping used in supermarkets, a member of the vinyl family made from a compound found in petroleum. Low cost, it protects against moisture loss, but has some oxygen permeability so it allows meat to bloom or maintain a red, fresh look.

RSC: RSC (Regular Slotted Carton) is the most commonly used style of carton. One side is glued, taped, or stapled during manufacturing, making this carton well suited for easy set-up, filling, and closure.

Retort Packaging: A flexible container typically formed from aluminum foil and plastic laminants. Can withstand in-package sterilization of the product, and, like metal food cans, can provide a shelf-stable package for foods. It allows for cooking food in the package , i.e. baby food or soups that have meat or vegetables that need to cook at a specified temperature to kill any micro-organisms to avoid botulism.

Repeat: A printing term referring to the total distance of one printed impression. This measurement is commonly used to determine the size of printing cylinder required to print the image.

Rigid Plastic Packaging: Freestanding plastic bottles and plastic fittings. The main raw materials used are PET, HDPE and PP.

Roll Flags: Flags are used to indicate a splice or an area of misprinted images on a roll. These tell processors where to take action to ensure smooth processing. Some machines will remove misprinted images from a roll, creating a splice and adding a flag.

Roll Geometry: The straightness of the edge of a roll of substrate is very important. Processing material through a machine can prove a challenge if the roll moves out of line with the machine feeds.

Sheet Feeder: A corrugating plant that has no converting equipment and produces only corrugated sheet. Its customers are typically independent sheet plants. The term ‘sheet feeder’ can also mean the device at the front of die cutters/flexo folder gluers.

Shelf-life: Refers most often to food products where the effective life of the product from the date of packaging is limited. Products beyond their effective date must be removed from inventory shelves because they are expected to be stale.

Shrink Wrapping: Plastic film that shrinks when heated, producing a tight, neat fit. The most popular form of grocery store meat packaging is PVC wrapping with foam trays.

Side Weld: A process used specifically on polyethylene bags where two substrates are bonded together and separated from the web at the same time by a tapered hot element commonly referred to as a knife.

Single-facer: The section of a corrugator which forms the corrugated shape in the medium, applies adhesive to it and then bonds it to the flat linerboard. The output from a single-facer is referred to as single- face board. Most corrugators have more than one single-facer to enable different flute sizes to be used.

Slitting/Slitter: A machine used to divide single, large rolls of web into smaller rolls. This is achieved by passing the entire web across cutting knives as it is removed from the larger roll. The divided webs are then rolled onto new, smaller cores. The same process is used to remove excess web from printed output rolls.

Splice/Butt Splice: Rolls of printed product often contain joins where two rolls have been fused, or misprints have been removed. Typical industry protocol limits the number of splices in a single roll as they can cause waste or slow down operations. Any splices in a roll should be flagged for easy identification.

Substrate/Film: Any base material, polyethylene, polypropylene or other material, used to make a packaging product.

Thermoforming: The process of shaping a plastic sheet of styrene or PVC under heat and pressure.

Three Side Seal Pouch: Any bag which has been heat sealed on 3 edges.

Transverse Direction: Opposite of machine direction, 90 degrees to the direction a film travels through a machine during processing, often used to decide the direction an image is printed on the film, and where cuts and seals are to be made.

Treated: Substrate which is to be printed on must be treated on the printing side by the substrate supplier. The opposite side of the substrate is not printed.

Vacuum Packaging: Rigid or flexible containers from which substantially all air has been removed before sealing. Carbon dioxide or nitrogen may be introduced into the container. This process prolongs shelf-life, preserves the flavors and retards bacterial growth.

WVTR (Water Vapor Transfer Rate), MVTR (Moisture Vapor Transfer Rate): Describes a material’s ability to repel vapor, which can damage the shelf life of certain products.