We were running Last of the Mohicans(no not the 1992 version Doris)
I had just completed a changeover when the film broke and all hell broke loose.The resulting fire was very intense but the fire trap did it's job and only the film in the picture head went up.
Unfortunately the other projectionist grabbed a bucket of sand and chucked that in the projector:eek(probably unnecessarily) as it would have just fizzled out.

My understanding was that it's not legal to manufacture trichloroethane (CFCs), and so its probably pretty expensive to purchase, no?

On the other hand, it seems that you can buy it from the VWR Scientific catalog ($60/liter), though it says "Requires special licensing for purchase." I suppose that's lab grade, and one might want to thin it before use (with what?)...

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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

True, but I think that point is a long way away. Under good conditions, nitrate can last a long time, and I would expect there to still be plenty of it around long after I am dead and gone.

"I've posted a 1951 guide to identifying nitrate from on that thread."

Identifying nitrate is not always easy; I would not expect everyone handling film to be able to do the tests, but I would expect them to be aware of the existance of nitrate, and that old prints could be made of this material. If they did receive a print about which they had any doubts, they could refer the matter to someone more experienced.

"Finally, I believe that Russian and Chinese 16mm nitrate is one of the topics covered in a new book being published next month on the history of nitrate, edited by Roger Smither of the Imperial War Museum film archive. I'll post details as soon as it's out. The Chinese certainly used it - I've seen a 16mm nitrate print of The Green River Flows East."

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Under good conditions, nitrate can last a long time, and I would expect there to still be plenty of it around long after I am dead and gone.

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I've seen research from the last couple of years suggesting that if the temperature and humidity can be lowered to appropriate levels, good quality nitrate (as opposed to bad stuff in which the cellulose base was manufactured from wood pulp with a high acid content) probably has a lifetime measured in hundreds of years.

That having been said, very few private individuals are able to maintain those collections. Reducing the temperature and humidity individually is not too difficult, but reducing both at the same time is a technical nightmare. Most dehumidifiers work by heating up the air until the moisture content evaporates out of it: therefore in order to condition air so that it is cold and dry, you need to dehumidify it and then cool it in a heat exchanger in such a way as to minimise the amount of moisture that is reintroduced. The plant needed to do this is fantastically expensive, both in terms of the capital equipment cost and running costs: I've heard that the National Film and Television Archive's vaults in Hertfordshire pay electricity bills of around £100k per year just for air handling. So I suspect the time when the only nitrate left is in the hands of archivists is probably no more than 20-25 years away, though I take your point about flagging the issue up in projectionist training.

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Do you have any idea when this print was made? As long ago as 1912, Pathe were aware of the need to use safety stock for non-theatrical purposes when they introduced their 28mm gauge, at least for prints, I think the negs may have been nitrate.

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Well the film (The Green River Flows East) was produced in 1948 so the print was certainly after then, though I don't know whether it dated from the film's initial release or was made later.

28mm negatives were indeed nitrate, with release prints on diacetate. My memory is sketchy on this but I believe the perforations were designed in such a way as to make it physically impossible to run nitrate elements on a domestic projector - they had four perfs per frame on one side and only one on the other, against the frame line - or something like that.

The IPE has an on-line "Preservation Calculator":
http://www.rit.edu/~661www1/sub_pages/8contents.htm

Kodak Molecular Sieves may be used to adsorb acid vapors and control film moisture content during storage in sealed containers:
http://www.kodak.com/country/US/en/motion/support/technical/molecular.shtml
http://www.kodak.com/country/US/en/motion/support/technical/vinegar.shtml
http://www.kodak.com/US/en/motion/support/technical/storage1.shtml

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

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quote:

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28mm negatives were indeed nitrate, with release prints on diacetate. My memory is sketchy on this but I believe the perforations were designed in such a way as to make it physically impossible to run nitrate elements on a domestic projector - they had four perfs per frame on one side and only one on the other, against the frame line - or something like that.

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Leo,

If you search 28mm Film & Projectors in FHF you will find a sample of 28mm film.

If vented film storage containers are used, it would be prudent for the vault rooms to either have high air turnover, or use carbon adsorption to help remove acid vapors from the circulating air. Segregating deteriorating rolls should also be part of that strategy.

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You mentioned that the platter running Nitrate was most likely a

"....... platter model was the Chernobyl MKV............" Surely the American equivalent is the AW-3-Mile-Island ?