Bags on a roll Continuous roll of seamless tubing perforated under bottom seal. Bags must be torn off to open.
Bottom seal bags Individually cut bags from seamless tubing, sealed on the bottom. Flat or side gusseted bags with a strong seal.
Butylated hydroxytoluene BHT A fat-soluble organic compound that is primarily used as an antioxidant food additive as well as in cosmetics, pharmaceuticals, jet fuels, rubber, petroleum products and embalming fluid.
Caliper The thickness of sheet material expressed in "points" or mils (thousands of an inch).
Cast film The fabrication of a film by continuously pumping the polymer through a straight slot die, then chilling this hot plastic immediately through contacts with a chilled roll. Film width is determined by how fast the chill roll pulls the film away from the die.
Corrugated A durable, lightweight material used for making cases. Corrugated packaging has an arched layer, called fluting, between smooth sheets, called liner. The corrugated cardboard most commonly used to make cases has one layer of fluting between two smooth sheets.
Cellophane Clear film derived from wood pulp has a memory and will crinkle like paper, it is a thin, flexible, transparent film formed from cellulose fibres. Cellophane is widely used in food packaging due to its high moisture barrier properties and sealability and is biodegradable.
Elasticity The ability of paper or plastic to rebound back to its original state after being stretched.
Extensibility The ability of paper or plastic to be stretched without breaking.
Extruder A machine that makes stretch film. It consists of a large steel barrel surrounded by heaters, which melt the plastic resin pellets. Inside of the barrel is a large screw to force the liquid plastic under pressure through a die to be made into plastic sheeting by either the cast or blown processes.
Extrusion A product formed by pushing material through a die.
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 polythene) between the layers.
End (bottom) weld A bag with the seal at the base of the bag. The seal is separated from the end of the bag by a small skirt. Bag length is measured from top to bottom of the bag including the skirt.
Euro-pallet A euro-pallet measures 1200mm x 800mm. A euro-pallet is smaller than a UK pallet.
Euroslot A horizontal slot punched in the bag for hanging.
Electrostatic discharge (ESD) Electrostatic discharge is the sudden flow of electricity between two electrically charged objects caused by contact.
Gusset Gussets are traditionally added to clothing to add breadth. Gussets are also a way of making polythene and paper bags bigger. Paper bags can have a bottom gusset. Poly bags can have a side gusset.
Gusseted bags Flat style bag with both sides or bottom tucked in to form gussets. Designated with three dimensions; Side Gusset (width x depth x length) or Bottom Gusset (width x length + gusset).
Grip seal A bag which is resealable and reclosable by two plastic components interlock at the top of the bag. The bag is reusable and flexible.
Gusset seal A flat-style bag manufactured with both sides tucked in to form gussets.
Grams per square meter (GSM) Refers to the substance weight of paper, relating to an area of paper that remains constant. Standard printer paper is around 80gsm.
High density polythene (HDPE) Film that has much higher stiffness, higher temperature resistance and much better water vapour barrier properties than LDPE film but is hazier. Common usages include grocery bags, packaging films and trash bags.
Header bags Side-weld bag with continuous seal along top, 2"-3" below fold. Bag is loaded and sealed from the bottom and typically has a hang hole.
Hole punch A mechanical device used to produce an air evacuation hole.
Half moon hole punch A punch hole that has not been completely cut through. Air is still able to escape through the bag.
Hot melt adhesive Stick to almost anything: foams, corrugated cardboard, fabrics, plastics light-gauge metals. Hot melts are as strong as mechanical fasteners and sealing tapes. Hot melts are virtually invisible therefore improving overall aesthetic.
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. Impulse heat sealers be used on many plastic materials to create strong permanent welds.
Inch A unit of length in the British Imperial system.
Lamination Composite product consisting of two or more sheets or films joined together with glue or adhesive.
Low density polythene (LDPE) Resistant to punctures and tears, non-porous and stretchable. LDPE is relatively strong transparent film with good tensile strength. This resin has good clarity but weak film strength. Primarily used for plastic food bags and poly sheeting.
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.
Perforations The practice of creating a long series of holes so that plastic film can be torn more easily. Postage stamps are one common application of this.
Polythene A simple thermoplastic polymer of ethylene. Highly puncture and tear resistant. Not affected by extreme temperatures. Does not possess barrier properties. Good clarity. Depending on its density, it may be low density (see LDPE). medium density (see MDPE). or high density (see HDPE).
Polymer A material made through the process of polymerization.
Polyethylene Polyethylene or polythene is the most common plastic. Polyethylene is of low strength, hardness and rigidity. Polyethylene has a high ductility and impact strength as well as low friction. It shows strong creep under persistent force. It feels waxy when touched. Most grades have excellent chemical resistance, meaning they are not attacked by strong acids or strong bases and are resistant to gentle oxidants and reducing agents. Depending on film thickness polyethylene can vary between almost clear (transparent), milky-opaque (translucent) or opaque. LDPE thereby owns the greatest, LLDPE slightly less and HDPE the least transparency.
Polypropylene A thermoplastic polymer of propylene. Has much higher melting point, thus better temperature resistance than PE. Preserves freshness with vapor and moisture barriers. Non-porous and excellent clarity. Possesses ability to withstand high temperatures.
Reclosable bags Seal-top reclosable bags can be made with or without a tamper-evident adhesive seal. Also includes zipper and slider zipper bags.
Recovery Stretch film trying to return back to its original form after it has been stretched. This action constantly pulls the load together since the stretch film tightly form-fits the load. Stretch wrapping continues to tighten the load as it settles during shipment, due to the recovery property, keeping the load safe and secure during shipment.
Resin identification code Resin identification codes (RIC) are codes defined by the European Commission. They identify the recyling status of a material. #5 PP applies to polypropylene and indicates the material is recyclable. #4 LDPE applies to low-density polyethylene and indicates the material is recyclable.
Tensile strength The ability of a material to resist a direct pull. Higher tensile strength is generally preferred for packaging products. When packaging heavier products a packing tape with higher tensile strength is preferred to help ensure a better seal. A stretch film with higher tensile strength will reduce shipping damages and increase load stabilization.
Tolerance Allowable deviation from a nominal or specified dimension. Minimum/maximum range of measurement.
Top sheeting A protective covering put on the top of a load to protect the top from dust, dirt and other objects that might damage or dirty the load.
TintTint: Film where only a little masterbatch is added to give a tint of colour.
Totally degradable plastic additives (TDPA) TDPA is produced by EPI Environmental Technologies. TDPA is designed to manage the lifetime of polythene products. Once their useful shelf life has passed they will degrade and then biodegrade into environmentally friendly products in a matter of years (rather than centuries). This type of packaging is also referred to as 'degradable' or 'oxo-degradable' packaging. Our LDPE polythene film is made from a virgin polymer. We add EPI additive to increase its biodegradability. Essentially EPI's TDPA provides a way to make conventional plastics degradable and biodegradable.