By Lisa Hennessey

This may not be a typical question faced by an archive or library, but it was a question Library and Archives Canada (LAC) had to answer back in 2009 when preparing to move its nitrate film collection to a new storage facility.

At first blush, the obvious solution to this question would be to bring in a scale and weigh all the boxes. However, in this particular case LAC needed to calculate only the weight of the nitrate film itself, not the weight of any containers, envelopes, film cans or albums. That was a challenge. How do you weigh a collection without actually weighing it?

LAC’s nitrate collection consists of 5,575 reels of film, dating from as early as 1912, and close to 600,000 still photographic negatives. From the early 1970s on, this material was stored at a facility on the Rockcliffe Air Base in Ottawa, Ontario. Built in the 1940s to house aerial photographic material produced by the Department of National Defence, the Rockcliffe building was showing its age by the late 1990s and a proposal was put forward to build a new storage building for the nitrate film. In 2011, construction on the new Nitrate Film Preservation Facility (NFPF) was completed.

The Nitrate Film Preservation Facility

Cellulose nitrate film, like a lot of material found in an archive or library, is flammable. However, unlike most materials, if deteriorated and improperly stored, nitrate can actually auto-ignite at temperatures as low as 49°C. If placed near an open flame, nitrate catches fire easily, combusts quickly and releases poisonous gases while it burns. If that weren’t enough, a nitrate fire cannot simply be extinguished with water or foam. This is because, while on fire, cellulose nitrate releases oxygen molecules, which, in turn, feed the flames. Therefore, a nitrate fire is normally extinguished only when it runs out of nitrate to burn. Needless to say, material of this nature must be stored safely so as to avoid putting other collections at risk.

Result of improperly storing nitrate film

Compartmentalizing a collection such as this will slow the spread of any potential fire and reduce the amount of loss. Instead of housing the collection in one open-plan vault, which would leave the collection vulnerable to a complete loss in the event of a fire, using multiple fireproof vaults decreases the chance of a complete loss.

In planning the vault layout for NFPF, LAC followed guidelines laid out in the National Fire Protection Association’s Standard for the Storage and Handling of Cellulose Nitrate Film (NFPA 40.) In this standard, section 6.5.5.1 states, “Extended term storage vaults shall be provided with horizontal shelves and vertical barriers that are spaced so that not more than two containers, each containing 305 m, (1000 ft) of film, shall be permitted to be placed in each compartment.” To comply with the first part of this guideline, NFPF was designed to have fire-resistant storage “cubbies” rather than open shelving.

View inside one of the vaults at NFPF

However, complying with the second part of the guideline was going to be a little trickier. Typically, collections are stored on the shelves by subject, creator or source. LAC now had to arrange its nitrate collection by weight.

Tune in next time for the thrilling conclusion!

Lisa Hennessey is a Project Coordinator in the Preservation Branch at Library and Archives Canada.