[Tig] Shrunken 35mm nitrate to HD-Spirit loses frame

Jim Houston jdhouston at earthlink.net
Fri Oct 17 19:44:37 BST 2008


On Oct 17, 2008, at 9:29 AM, Rob Lingelbach wrote:
>> I guess just one stray static spark could cause a nitrate fire.
>
> I've watched the training film on handling nitrate film, produced
> I believe by Kodak, and it was necessary, in order to burn nitrate
> film of a certain condition, to hold a flame to it.    However, I
> don't remember if flammability increases with deterioration of
> the film over time (gas and bubbling vinegar state).

Yes, it does.  The base of nitrate film is made by dissolving cotton
in nitric acid and adding camphor as a plasticizer.  (nitrocellulose)
Use glycerol instead of cellulose and you get nitroglycerin.

This is the similar stuff known as 'gun-cotton' because it was used
as a propellent in early firearms, and as the base for plastic  
explosives.
(The military stopped using it for that purpose as it was too  
dangerous!)

Deterioration over time causes increased flammability. The bubbling
is nitric acid released to the surface.
Friction, heat, and sparks can all cause spontaneous combustion
of a degraded film.

Jim




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