Library of Congress film preservation -- the ultimate archive

Cellulose nitrate is a very flammable material, but it also happens to be a very high quality clear plastic — 35mm motion picture film was almost exclusively nitrate, from the beginning of filmmaking through 1950 or so in the US, possibly as late as the early 60s in Russia and eastern Europe. But after a number of notable fires, it was banned for projection in a theater except under very special circumstances.

It was replaced by cellulose triacetate, but because of nitrate’s nature to deteriorate, the content on all of the thousands of previously collected films was at risk. They needed to be copied to safety prints, which is primarily what we do.

--lots more at this interesting article