By Lisa Hennessey
In 2011, construction of Library and Archives Canada’s (LAC) new Nitrate Film Preservation Facility (NFPF) was complete. This building was constructed following the National Fire Protection Association’s Standard for the Storage and Handling of Cellulose Nitrate Film (NFPA 40) and, as such, LAC had to follow certain rules. One of these rules limits the total amount of nitrate film that can be housed in each fire-resistant storage compartment to 305 metres (1,000 feet).
The NFPA 40 guidelines speak in terms of length of film and were clearly written for motion picture film, this format being easily measured in metres or feet. Dealing in length of material is harder, however, when planning for the storage of nearly 600,000 still photographic negatives of various formats stored across 1,600 containers. How much is 305 metres when you are talking about a container full of 4×5 negatives? Instead, LAC decided to deal in weight. It was estimated that 305 metres of motion picture film represents approximately 4.5 kilograms (10 pounds) of nitrate. This would be our new maximum amount per compartment.
For the most part, LAC’s nitrate negatives are housed in paper envelopes (sometimes multiple negatives per envelope) and stored in cardboard containers. To determine the total weight of nitrate film per container the first step was to find out the weight of an empty container. LAC staff weighed an empty sample of each of the various container types found in the collection. We also weighed an empty sample of each size of envelope. Next, a survey team worked through the entire collection weighing each full container and then estimating the number of envelopes of each size inside. Once this was known, it was simply a matter of subtracting the weight of the physical container and the paper envelopes from the total weight, which resulted in a pretty good estimate of how much nitrate was in each container. Any container that was found to have more than 4.5 kilograms of nitrate film was rehoused in two containers.