Got pointed at one interesting Kodak publication specifically addressing the fire preservation question for microfilm, which is closely related to but not identical to pictorial B&W film. In <http://graphics.kodak.com/docimaging/uploadedfiles/en_D-31.pdf> (note, PDF) they say: Cabinets and Safes For smaller quantities of records, a fire-resistant cabinet or safe of the type described by NFPA 232 will provide considerable protection. Such a safe should protect records against a severe fire for at least four hours. Many fire-resistant safes and cabinets use a type of insulation that when heated releases moisture and thus fills the interior of the safe with steam during a fire. This can cause melting or stripping of the film emulsion layer and loss of the image. For protection, films stored in such a safe should be placed in moisture-tight cans, as described under “Humidity Control” in this publication. It is preferable to use fire-resistant safes that are available with an inner chamber sealed against moisture. These are classified by Underwriters’ Laboratories, Inc., as Class 150 Record Containers. Film damage caused by steam is not a problem with these safes. (dd-b again) Which leaves me wondering whether a UL Class 350 cabinet has this steam problem or not. The spec seems to say max relative humidity of 85%, which seems to me to rule out "fills with steam". Regrettably, Kodak didn't mention the UL spec for the simpler cabinets. -- David Dyer-Bennet, dd-b@xxxxxxxx; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info Nikon DSLR photo list: http://d4scussion.com
