film and sound archiving, refrigerated film storage, movie storage
(1) “Film Specifics: Stocks and Soundtracks,” The Home Film Preservation Guide, 19 May 2008
(2) “Videotape Preservation Fact Sheet,” The Association of Moving Image Archivists (AMIA), 19 May 2008
(3) Adelstein, Peter Z. (2004). ” IPI Media Storage Quick Reference,” Image Permanence Institute. 19 May 2008
There are many different varieties of motion picture film. However, motion picture films each have the same physical structure which consists of two primary parts. They are the base and the emulsion.
Emulsion – The thin layer of gelatin where the photographic image resides. The side of film with the emulsion is normally has a dull, tacky finish while the base side appears smooth and shiny. With color film where both sides of the film appear glossy, the emulsion side can be identified by holding the film to the light. The emulsion side is the side where the image appears raised.
Film Base – A transparent substrate that supports the photosensitive emulsion that lies on top of it. Even though there are many layers and coatings associated with the emulsion layer, the base normally accounts for the majority of the thickness of the film stock. Historically, there have been three major types of film bases used: nitrate, acetate, and polyester.
Some forms of media (like CD-ROMS) are capable of tolerating a variety of storage conditions. However, most moving image media slowly and steadily decay without special environments that lead to a long, useful life. Each medium has its own special requirements. For example, dyes in color photographs fade spontaneously in a short period of time. Low-temperature storage is the only way to preserve them. The silver particles in black and white photographic images are very sensitive to high humidity and airborne contaminants.
Media preservation depends on our understanding of the vulnerabilities of each media type so that the proper storage conditions can be provided. When elements of a collection are older or already damaged, storage conditions that slow down the rate of deterioration are important. The presence of vinegar can be evaluated by the use of A-D testing strips. Further information about this process can be found here.
There are three categories of environmentally caused decay. They are biological, chemical, and mechanical.
Dampness is a serious environmental threat to media collections because it contributes not only to mechanical decay but to biological and chemical decay as well. (3)