Acetic acid (Vinegar Syndrome) detection in Cellulose Triacetate (CTA) motion picture film materials
Introduction
One of the most significant failure mechanisms of CTA film support is its degradation due to exposure to hydrolysis inducing storage temperature and relative humidity (RH). The rate at which this degradation occurs varies with storage environment, manufacture, efficiency of laboratory processes, the coating on the film, i.e. magnetic sound coating doubles the rate of degradation as compared with film materials with a photographic emulsion. It is also influenced by the material of which the container is made, and whether it traps the acetic acid (vinegar) or allows its evacuation.
Detecting It
It is possible to detect an active vinegar syndrome state inside a film container by briefly opening it. If a vinegar smell is present, active degradation is taking place. If the material is still stored in the tin-coated metal raw film stock can supplied by the film stock manufacturer, the interior may exhibit brown powder and may even be corroded. This indicates that active film base degradation started some time ago.
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