Polyethylene
Depending on its density, it may be low density (LDPR), medium density (MDPE), or high density (HDPE). For Shrink Film low density (LDPE) and linear low density (LLDPE). Linear Low Density Polyethylene is tougher than Low Density Polyethylene and has better heat seal strength, but has more haze. Polyethylene shrinks 50 to 65 percent machine direction and 0 to 25 percent transverse direction. It is a more cost effective solution than other shrink films.

PVC
Polyvinyl Chloride. A tough, stiff, very clean film. The oriented version is used mainly for shrink film applications. PVC is cleaner than Polyethylene and shrinks at a lower temperature. The shrink is 65 to 75 percent machine direction and 10 to 30 percent transverse direction. It is a more expensive solution than Polyethylene.

Polyolefin
a very high shrink film in both directions 50 percent transverse and 80 percent machine direction. The strength, clarity and high gloss makes it a good film for retail packaging. Polyolefin is the most expensive of the shrink film solutions.

Density
Weight per unit volume. Films with a low density offer more coverage per weight of film.

Center Folded Film
Film folded in half in the machine direction and then wound into roll form.

Forming Head (Plow)
A mechanical device used to shape flat wound film into the desired bag shape needed for a particular package.

Heat Sealing
Joining plastic films by controlled application of heat and pressure to the area to be sealed.

Lap Seal
A method of sealing, plastic films where the two pieces to be sealed are over-lapped, then heated to form a seal.

Machine Direction (MD)
The direction parallel to that taken by the majority of molecules in plastic film, or the direction of the film web as it moves through the film-making machine. Also called Longitudinal Direction.

Shrinkage / Percent Shrink
The decrease in dimension of a film when it is subjected to heat.

Transverse Direction (TD)
The direction at right angles to that taken by the majority of molecules in a plastic film or the direction at right angles taken by the film web as it moves through the film-making machine.