Exploring

Inherent Vice: Film Supports

Polyester Film

Polyester film, a generic term for polyethylene terephthalate (PET), was developed in the mid-1950s. During the 1960s and 1970s, it gradually replaced acetate for sheet films. Polyethylene naphthalene (PEN, a modification of PET) was introduced in 1996 for amateur roll film, under the brand name Advantix, but other roll films are still made from cellulose acetate. Polyester film is a synthetic polymer, unlike cellulose acetate and cellulose nitrate, and it does not contain solvents or plasticizers. Thus, it is inherently very chemically stable. Polyester film is also used for archival quality enclosures for collections, which will be addressed in Session 5: Collections Care.

Identifying Polyester Film

Rainbow colors can be seen along the edge of polyester film when it is viewed between two polarizing filters in a mount.

Polyester film, like acetate film, may be marked with "SAFETY" on the edge. Polyester can also be identified by viewing it between two polarizing filters, which produces rainbow colors. In addition, polyester roll film will transmit much more light than acetate roll film when held up to the light and viewed edge-on.