Chemical breakdown is destroying the world's movie film libraries and archives at an alarming rate. Technically "cellulose acetate decomposition" this self-catalyzing degradation of the movie film backing is more commonly known as "Vinegar Syndrome".
Once movie film has vinegar syndrome starts, there is only a small window of time, months, before the movie film starts to physically morph -- curl and stretch and then shrink. Once the movie film shrinks, it becomes brittle, and bowed. In some cases movie film may be treated with chemicals (reportedly camphor, etc.) that will temporarily allow it to run through a projector -- with much distortion in the images -- one last time. This process is profoundly expensive and performed by only one or two labs in North America. Results are not guaranteed.
Vinegar Syndrome is contagious: Other movie film can be "infected" -- through the air. If you can "smell your movie film" -- any smell like vinegar -- you are losing it, fast! If YOU can smell it, then chances are that ALL your other movie film -- stored with the movie film that you CAN smell -- already has it, too. Run, don't walk, to digitize your movie film. Once Vinegar Syndrome starts, there is no way to reverse it.
Notice: Film with vinegar syndrome does NOT necessarily have an odor of vinegar. In many cases, physical morphing of the movie film -- causing it to curl and ripple, like the edges of macaroni -- can be seen without any odor.