Robert Bradspies wrote, "Old decomposed nitrate should be considered a HIGH EXPLOSIVE." This is true only of movie film and that's because it is stored rolled in a metal cannister. I ran across some severely deteriorated nitrate movie film years ago in the collection of an arboretum's archives. The local police and fire people wanted no part of it, but the bomb squad for a state agency were thrilled and had a new experience exploding the stuff. I have never heard of cellulose nitrate film exploding if it's in sheet format. It would require a combination of extraordinary housing and environmental conditions for sheet film to combust simultaneously. I am not suggesting that nitrate negs in still photo collections don't require special attention-- they do. For further information, an excellent reference is "Archives & Manuscripts: Administration of Photographic Collections" by Ritzenthaler, Munoff and Long. It's part of the SAA Basic Manual Series, and I think it's the best of its kind. Michael McColgin Phone: (602) 542- 4159 Preservation Officer Fax: (602) 542- 4402 Arizona State Archives Email: [log in to unmask] 1700 West Washington Smoke Signal: 0 oo 000 o0o0 Phoenix, AZ 85007 Conservators make it last longer.