Old film reels can spontaneously turn into explosive dust

In the early days of Hollywood, movies were printed on cellulose nitrate, a substance so chemically unstable it shares a molecular structure with explosives. This film stock doesn't just burn; it creates its own oxygen as it combusts, meaning a fire cannot be smothered by water or foam. By the time a reel begins to smell like dirty laundry, it has entered a state of 'auto-catalytic' decay, where it releases acidic gases that eat away at the remaining images until the entire film collapses into a pile of rust-colored, highly flammable dust.