This paper reports data on cellulose triacetate (CTA) film base stability obtained at 21 and -16 °C over a 10-year period. Results demonstrated the potential of subfreezing storage temperatures for stabilizing CTA films that have already started to decay. After over 10 years of storage at -16 °C, no change in free acidity was observed for film that had been predegraded to the onset of vinegar syndrome. Data obtained by natural aging at 21 °C, 50% relative humidity (RH) indicated that film acidity at least doubled within 5 years. These results were consistent with earlier predictions based on accelerated-aging tests and reaffirmed the inappropriateness of film storage at room conditions. Data on the effect of changing temperature and/or RH on CTA film base stability are reported. Results did not reveal that changing conditions caused unexpected extra CTA film base decay. The data reinforced the potential value of the time-weighted presentation index model in informing storage decisions.