Focus on Film: A Little Historical Background

Film stripThis issue of Climate Notes is focused on film collections. Traditionally, movies were shot on film, developed and edited using film techniques, then turned into film prints. In the late 19th century the most commonly used film support was cellulose nitrate, which had a tendency to curl, was highly flammable and was chemically unstable in many instances. Despite the fire hazard, nitrate sheet film was in widespread use until the mid-1930s and nitrate roll and motion picture film use continued into the early 1950s. An alternative to nitrate film, cellulose diacetate or "safety" film was introduced in the 1920s. Cellulose diacetate was less flammable than nitrate, but suffered from shrinkage, discoloration, and embrittlement. In the 1930s, more stable butyrate acetates were developed for specific applications (acetate butyrate, acetate propionate). By the late 1940s these were gradually replaced by cellulose triacetate. Acetate supports were initially thought to be more stable than nitrate, until instances of cellulose triacetate instability in high humidity locations began to be reported. By the 1980s archivists in moderate climates were finding triacetate decay in their collections as well, suggesting that high humidity was not the only problem. It should be noted that research has demonstrated that stored properly (i.e. low temperature); nitrate can last, sometimes even longer than acetate.

A film can be many things – entertainment, art form, historical record, or cultural artifact. In most archives, libraries, and museums, moving images are primary documents for display, education, and research. The Heritage Health Index Report on the State of America's Collections (Heritage Preservation, 2005) reported that collecting institutions in the US house over 86 million films, videos, DVDs, records and cassettes, and that the condition of almost half of the material is unknown.

IPI has researched the stability of both nitrate and acetate film in various environments, developed a diagnostic tool for vinegar syndrome, and developed specific storage recommendations for various types of media collections. Individuals responsible for preserving, restoring, housing, and providing access to film collections need to understand the three step preservation approach that IPI has developed based on decades of work with film collections:

  • Know the collection materials,
  • Assess their condition, and
  • Store them in the proper environment.