Re: A little about Nitrate Films

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From: James Young (jamiehy@globaldialog.com)
Date: 02/16/01-08:48:28 AM Z


>I used to work for a motion picture lab in Washington, DC. We did a lot of
>work with the National Archives, and every once in a while Nitrate films
>would be sent over to be reprinted, or a copy negative made.
>
>When Nitrate film decomposes, it becomes VERY unstable, and can explode just
>by being dropped from table height. Cellulose Nitrate is also called gun
>cotton. Its manufacture is very similar to nitroglycerin. Most insurance
>policies become void if the material is around, because of its unstable
>nature (The labs did also, so we didn't do a lot, but people still sent it
>in.)

Actually nitroglycerin was an additive to the celluose nitrate. The
process was different. I've been photographing in a large ball powder
plant, and have been in the Nitroglycerin area. The process
originally used was a batch process. The signs have explosive
materials limits of 9000 lbs in some of the buildings. The signs
would indicate that up to 9000 lbs of nitro would be stored there.
The buildings were built inside bunkers designed to direct explosions
upward if a building happened to blow. The whole process was gravity
fed. The mixing of the nitric acid and glycerin occurred at the top
of a hill, and the material flowed to various buildings down gently
sloping lead troughs for more processing. All lighting was on the
outside of the buildings. The lights were directed through windows.
The floors and other surfaces were all covered with lead. Very
strange buildings, but a great place to take photos. The modern
method of making Nitroglycerin is a continuos mix/feed process so
there isn't a lot of nitro all in one spot. Jamie


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