Kristen McCormick, Michael R. Schilling, Miriam Truffa Giachet, Joy Mazurek, Herant Khanjian, and Tom Learner
An analytical survey was conducted of animation cels in the Walt Disney Animation Research Library (ARL) collection, made for animated films from 1929 to 2003, that addressed three main topics: (1) characterization of cel polymers and plasticizers; (2) assessment of cel degradation in storage; and (3) assessment of cel degradation and microenvironments in passe-partout mounts.
FTIR was helpful in differentiating the main polymer types: cellulose nitrate, cellulose diacetate, cellulose triacetate, and polyester. The majority of the cels were made from cellulose diacetate before 1981, and cellulose triacetate thereafter. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) identified a number of distinct plasticizer mixtures–primarily triphenyl phosphate mixed with phthalates–in the diacetate and triacetate cels. Estimates of the acetyl content by gas chromatography/mass spectrometry, which assessed the degree of substitution in the cellulose acetate cels, revealed that few cels showed evidence of hydrolysis. Levels of acetic acid vapor produced by cels in storage vaults at the ARL, as measured by A-D Strips, confirmed that few cels were at risk. Finally, the concentration of acetic acid vapor in passe-partout mounted cels for traveling exhibition, as measured by GC/MS and A-D Strips, was minimal.
Animation cels represent a unique and important cultural legacy of the 20th century. This study revealed that cellulose acetate cels have a range of compositions, which ultimately may affect their stability. Further research is needed to find optimum storage environments that reduce the rate of hydrolysis of the cellulose acetate without damaging the ink and paint layers.