Optics
The visual properties of a material, such as clarity, haze and gloss, that are first noticed by an end-user and the point-of-purchase customer. These visual properties distinguish premium shrink films from commodity shrink poly. Good optical properties display the customer's product to it's best advantage.
Clarity
Refers to the optical distinctness with which an object can be seen when viewed through the film. Clarity is a measure of freedom from distortion and is expressed as a percentage, with the higher the value, the clearer the visual image.
Gloss
The visual impression of sparkle or luster from a film. Gloss is somewhat dependent on gauge and therefore the gauge of a test sample accompanies the value. The higher the value, the more glossier the film.
Haze
A film's light scattering property which gives it a cloudy or milky appearance. Haze values are expressed as a percentage; with a higher percent indicating greater haze. Since the thickness of the film can affect these values, the gauge of the sample tested accompanies the haze value.
Memory
After shrinking, the film retains the same characteristics. In other words, the film has good memory.
Cold Temperature Flex (Low Temperature)
Ability of a film to perform at low temperature without fracture or failure.
Modulus of Elasticity-Stiffness
The stiffness or resistance to bending of a packaging film The higher the modulus value, the stiffer the material. Typically, a film with a higher modulus machines best on a high-speed wrapper.
Slip
That quality of a film that permits it to move easily over metal or against another piece of film (See Coefficient of Friction).
Cold Slip
The amount of force required to slide two cold surfaces of film against themselves.
Hot Slip
The amount of force required to slide two heated surfaces of film against themselves.
Tack
A property of a film that is characterized by its adherence to metals and/or another sheet of similar film (See Coefficient of Friction).
Oriented
The stretching and aligning of a material's molecules at temperatures below its melting points.
Balanced (Biaxial)
Equal orientation in both LD (longitudinal direction) and TD (transverse direction), i.e., 3 x 3 or 5 x 5.
Biaxially Oriented Film
Oriented along X and Y axes.
Unbalanced (Monoaxial)
Unequal orientation in LD and TD; preferential or monoaxial orientation.
Monoaxial
A film which is oriented to shrink in one direction (longitudinal or transverse) only.
Preferential Shrink
The characteristics of a shrink film which enable it to shrink more in on direction (longitudinal or transverse) than the other. Longitudinal orientation is accomplished by a device which stretches the film in the machine direction. Transverse orientation is induced by a process such as tentering which applies across the web stretching.
Dimensional Stability
Capability of a roll of material to maintain slit width during typical storage and distribution conditions.
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