Saran is derived from the polymerization of vinylidene chloride or the copolymerization of vinylidene chloride with lesser amounts of other unsaturated monomers, most often vinyl chloride or acrylonitrile. This thermoplastic polymer was first polymerized in 1920 by the Dow Chemical Company. Today, it is most often used in copolymers to form packing film, rigid pipe, and fibers. As a film, it acts as a barrier to oxygen, water vapor, grease, and liquid. About 85% of the polyvinylidene chloride produced is used as a thin layer between cellophane, paper, and plastic packaging to improve barrier performance. Saran Wrap, well known as the cling wrap designed for household and commercial use that Dow Chemical first introduced in 1949, revolutionized the food packaging industry. Today, saran films are used as a barrier package for cheese, baked goods, processed meats, and seafood.

Saran is produced by polymerizing vinylidene chloride with other monomers to form long stereoregular chains. These chains are susceptible to crystallization, giving rise to the superior clarity and excellent barrier properties of saran.