Acetate film, a slow burning film base, was dubbed safety film and used for film prints as early as 1919. Acetate film can suffer from a condition called acetate deterioration (aka vinegar syndrome due to the smell of acetic acid off-gassing) which is accelerated by storage in high humidity. Under good storage conditions, acetate film has an excellent life expectancy of more than 100 years. Deteriorating film will shrink, warp and become brittle so that eventually the emulsion (the image carrier) puckers as the base (the acetate film) shrinks. Film in this condition can, remarkably, sometimes be preserved. In a state of advanced deterioration, the film roll becomes "glued" and the film cannot unwrap.