Safety film
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Photographic film called safety film is made with a film base of either acetate or polyester. Bases known as "acetate" are chemically either cellulose diacetate, cellulose acetate propiarate, cellulose acetate butyrate, or cellulose triacetate. Beginning in the 1920s, acetate replaced nitrocellulose (nitrate) film bases used previously as the film stock used in both amateur and professional applications. Polyester bases began to be developed in the 1940s.
Cellulose triacetate films are still in wide use today for applications such as original camera negatives, but have largely been replaced with polyester, which is more stable and durable for archival and post-production purposes.