Plastic wrap, also called cling film or cling wrap, is a thin, plastic film used mainly for covering food items to keep them fresh. It was invented in 1953 by a scientist attempting to create a thick plastic covering for his car. Glad Wrap and Saran™ Wrap are the two most well known brands worldwide and are often used as generic terms. The first plastic wrap on the market was made of polyvinylidene chloride (PVC), commercially known as Saran, though today many brands — including Saran™ Wrap — are made of low density polyethylene (LDPE).
One of the benefits of using plastic wrap is that it usually forms a seal without the use of adhesive by clinging to itself or to the container. It commonly comes on a roll packaged in a box with a cutting edge, although perforated varieties may also be available.
PVC was originally used for plastic wrap because it has a low permeability to oxygen, water vapor, and flavor and aroma molecules. There have been concerns in recent years about the toxicity of PVC and its tendency to leach chemicals into foods. LDPE is cheaper and easier to manufacture than PVC and may be safer for household use and easier to recycle. Nevertheless, PVC is still more widely used, especially in the food catering industry, as it clings better, is less permeable to oxygen and flavors, and better protects against freezer burn.
Neither PVC nor LDPE cling well on their own, so other polymers such as polyisobutene (PIB) or polyethylene-vinylacetate (EVA) must be added to the film. The first plastic wrap marketed in Australia, Glad Wrap, used an edible gum adhesive, and some newer products use similar technology. Glad Press’n Seal, for example, has pockets of edible adhesive that are activated when the film is pressed.