Deteriorated Acetate Recovery and Disaster Recovery

The Chicago Albumen Works has developed a unique procedure for removing, duplicating, and preserving the photographic emulsion from deteriorated acetate negatives. Introduced in the early 1930's to replace nitrate based films, acetate negatives frequently undergo excessive shrinkage, which proceeds until the gelatine emulsion can no longer adhere. The emulsion then separates from the acetate base, usually in irregular furrows, and as the shrinkage continues, the gelatine eventually folds onto itself and frequently breaks.

This process is accompanied by a strong acetic-acid-like odor, which can be easily detected and which can serve as a warning of impending self-destruction. Once furrows begin to form, either in the emulsion or in the gelatine anti-curl backing, the negative becomes virtually useless, and the emulsion will soon be cracked beyond all recognition.

The method employed by the Chicago Albumen Works to salvage these deteriorating negatives involves four steps. First, the emulsion is chemically released from the acetate base. Next, the image pellicle (the removed emulsion layer) is cleaned and placed in a series of carefully controlled solutions, which allow its distortions to relax. Thirdly, the flattened pellicle is duplicated using our standard duplication procedures, producing an archival film interpositive and an accurate duplicate negative. And lastly, the pellicle itself is dried and returned (unsupported) to the collection.

Alternatively, the relaxed image pellicle may be directly scanned, with the pellicle dried and preserved as usual. For institutions moving to digital access of their photograph collections, scanning is an appropriate preservation and access program, for the preserved pellicle is extremely stable and only requires a modest temperature and humidity environment to be considered archival.