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which indicates that it may have been manufactured even earlier and was at or near the end of its expected life. Once such film begins to deteriorate, it does so at an accelerating rate, especially under adverse storage conditions. The quality of the film at the time of manufacture also affects the rate at which it will deteriorate. Film manufactured during the World War II period, when certain chemicals were in short supply, is more likely to deteriorate prematurely. Some of this film came from that period.
Another factor contributing significantly to deterioration is the presence of hypo or residual chemicals used in the processing of the film. It is quite common to find such chemicals on film that has not been thoroughly washed after processing. This collection was not tested to see if such chemicals were present. Testing for hypo is a standard archival practice.
Adverse conditions of storage. Humidity in the film vaults at Suitland is not controlled. Many archivists are of the opinion that excess humidity is a greater cause of film deterioration than is warm weather. Some vaults at Suitland have relative humidities in the mid-seventies and eighties. The work under way at the time of the fire would have remedied this, but much of the film has already been subjected to this condition for six to eight years since it was donated. Without humidity control, cooling will frequently raise the relative humidity.
One of the factors contributing to the August 1977 fire at the Suitland vaults was a malfunctioning air-cooling system. Although repairs have been made, the system has continued to present problems and has not functioned effectively. More extensive repairs were not made recently because a new system was being installed. Leaks in the system have required that GSA engineers add coolant to the system when employees noticed that the coolant pipes were warm. For the two months before the fire, a period that was unseasonally warm, GSA engineers added coolant an average of three times per week. Thus the film was subjected to continual cycling between warm and cool temperatures as the system lost coolant and it was replaced. Such cycling also accelerates deterioration Coolant was last added to the system five days before the fire .
Another factor contributing to the film deterioration is the accumulation of oxides of nitrogen caused by the breakdown of the chemicals in the film base. Since there is no means to introduce fresh air into the vaults regularly, escaping gases from decomposing film are circulated throughout the vault where they may attack other film, causing image loss and further deterioration. At present the only means by which air in the vaults is exchanged is by the air movement caused