Handling plastic and metallized films through converting processes (printing, laminating, slitting, metallizing, bag making, and so forth) involves the simple steps of unwinding a "web" of flat material wound in roll form, working on it in some way, and then rewinding it. Defects of webs are re-lated to, but not exactly identical to roll defects. The precise tendencies of plastic materials in converting processes to reshape and deform can be quantified with standard laboratory tests and understood in terms of the tensile properties of materials. Three basic strategies are used to provide barrier performance in plastic films. Vacuum metallized aluminum coating is a special case of one of these strategies. Its protection follows the logic of other trouble-shooting tactics for plastic films.
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