My SO is trying to sell some airhandling equipment to a customer that needs to store old movie film (70mm was specifically mentioned, I don’t know if that is all.)
One of the concerns is being able to handle anything that might be off gases from the film itself. Does anyone know when the film might give off?
Thanks
I have no idea what off gasses from movie reels, but if I had to take a WAG, he’s going to be in the market air handling equipment that is ‘vapor proof.’ This way if it’s off gassing anything that’s flammable, you won’t have to worry about it getting near a spark from a motor.
Modern film doesn’t off-gas much of anything unless they’re freshly cleaned, in which case the film cleaning solvents will be evaporating as the film dries.
What you do have to watch out for is old nitrate stock, which off-gases acetic acid (known as “vinegar syndrome” and is extremely inflammable, requiring storage in fireproof vaults. Acetate film is somewhat safer, but still needs a bit of care.
Modern polyester bases (from the 1950’s onward) are essentially inert. It just needs the classic “cool, dry, dark” storage and no particular precautions in terms of air handling or fire control.
If you want to learn more, the Image Permanence Institute has a PDF document on film storage.
My father-in-law was a firefighter in Hollywood in the '40s. He’s told us about film fires at the studios back then, so I called him to ask your question.
He says the old celluloid film off gassed picric acid. Celluloid film is cellulose nitrate. As it degrades it “sweats” picric acid (2,4,6-trinitrophenol).
Picric acid in the dry form is highly explosive. It’s highly shock and friction sensitive.
I couldn’t find any cites specificly about old movie film. Most of the Google entries seem to be about bomb making. The one I linked to is just the chemistry.
Thanks gotpasswords. That gives him someplace to start from.
From the little he knows right now, it sounds like there is probably nitrate stock involved. He mentioned a copy of the Wizard of Oz. Now I’m going to have to grill him on who this customer is.
If the film is from the 1940s or before it may include nitrate stock, but to the extent that it’s 70mm, it’s almost certainly not nitrate. A few experimental widescreen formats were developed in the 1930s, and may have used nitrate film. However very little footage was shot in these formats, and even less still exists. Seventy-millimeter film as we know it today wasn’t developed until the 1950s, when nitrate film had all but been replaced by acetate or polyester “safety” film.
Cool. Thanks for checking with your FIL, picunurse. I’ll pass that on.
I’m always surprised what and who people here know, but I never seem to doubt that someone will know.
nitrate film is cellulose nitrate. It will not degass acetic acid as suggested above (unlike acetate film which as the name suggests will release acetic acid).
according to kodak
Cellulose nitrate-based film (nitrocellulose) was manufactured by Kodak from 1889 until 1951. The films are flammable, and, depending on their age, can be in various stages of decomposition. During decomposition, the film can release nitric oxide, nitrogen dioxide, and other gases, which may be irritating to the eyes, nose, and throat.
from http://www.kodak.com/global/en/service/faqs/faq5020.shtml
However as pointed out it is unlikley to be nitrate film
NFPA 40, Standard for the Storage and Handling of Cellulose Nitrate Film
Everything you never wanted to know about fire protection hazards of film. Click down the bottom where it says “Preview this document” and follow the prompts. You can see the document, you just can’t save or print it.
See “vinegar syndrome”.
http://www.kodak.com/US/en/motion/support/technical/vinegar.jhtml?id=0.1.4.11.12.4&lc=en
Thanks folks. This is turning into an even more interesting quote for my SO. Now is sounds like there may be films being stored from as far back as 1920ish.