Motion picture films are most likely to be on either cellulose nitrate or acetate bases. It is extremely dangerous to retain original motion picture films on cellulose nitrate base, since they are highly flammable. For most small institutions, it is best to store nitrate films in offsite cold storage (service copies might be made onto videotape) or transfer them to an institution that is better equipped to care for them. Cellulose acetate base films are not a fire hazard, but they will deteriorate over time; this deterioration can be slowed by cold storage.
Like other enclosures, film containers should be chemically stable and should physically support the materials, fitting the film as closely as possible. Film containers should pass the Photographic Activity Test (PAT) to ensure that there is no damage from glues or additives contained in the enclosure.
Boxes or cans are acceptable for film storage; these may be made from acceptable plastics (polypropylene or polyethylene), preservation-quality cardboard, or noncorroding metal. Some storage containers are vented. At room temperature, this is an advantage for acetate films, allowing acetic acid vapors to disperse; at lower temperatures, venting does not make as much difference. Film containers should be stacked horizontally, with the film lying flat. In general, films should be stored with their tails out and rewound before projecting.
Be aware that the National Fire Protection Association (NFPA) has guidelines for the construction of cabinets and vaults that house nitrate motion picture film. Meeting these guidelines is complicated and expensive, and thus impractical for most small institutions, but not meeting them can be dangerous. In addition, local law may require that you meet the NFPA guidelines. As noted above, offsite cold storage or transfer to another institution are often the best options.
Do not project old film that has been stored for many years, since projecting fragile film can cause additional damage. The film must first be inspected using special film-handling equipment. An inspection will identify edge codes that may provide clues to film base and dating, signs of mechanical damage (e.g., splices, broken sprocket holes, shrinkage), signs of chemical damage (e.g., vinegar odor), and/or signs of mold damage. See the Film Forever Web site and The Film Preservation Guide: The Basics for Libraries, Archives, and Museums for detailed descriptions of the inspection process and additional information on storage. If you cannot inspect film in-house or at a nearby institution equipped for film inspection, commercial companies can provide this service.
Molecular sieves are desiccants that can be placed in a film can (between the film roll and the interior wall of the can) to absorb moisture and acetic acid vapors. They are expensive, so should be used selectively.
Creating a new master copy of the original is the best way to ensure preservation of motion picture films. The master is used to make access copies, with the original retained in cold storage. This type of copying is a complex and very expensive process and therefore not practical for most institutions—and not justified unless the film is of significant importance. A more manageable alternative for smaller institutions is making service copies on analog or digital videotape. In the future, it may be possible to convert original films directly to digital files rather than copying them to film, but the original quality of the image and sound cannot yet be captured satisfactorily in this way. See Session 6: Reformatting and Treatment.