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This topic comprises 5 pages: 1 2 3 4 5
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Topic: Film is nitrate... now what?
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Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
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posted 07-20-2006 09:56 AM
OK, now it's my turn to play 'I can be a bigger edge code geek than you' with Stephen. Just had a closer look at Philip's photos, and noticed two interesting things. Firstly, I didn't misread Jeff Joseph's edge code chart; I just saw one set of codes. There are two sets of codes on that element - two circles (1939) and two triangles (1941). Secondly, if you look at the positive 'Eastman' legend (the pic captioned 'Crop circles next?' below), it looks like there's a negative stock mark printed through immediately underneath it (for example, look to the left of the 'N'). Given that and the fact that the 'nitrate film' legends on the earlier pictures are opposite orientation, my guess would be that you're seeing print-through from both internegative and fine grain pos previous generations, possibly from both pic and/or track elements.
The 1941 stock mark is still a puzzle, though, as it suggests that this copy cannot have been printed until a couple of years after the film's initial release.
Given that the shipping box is labelled 'Rank Organisation', I'd also speculate that this print can't have been exported to the US until at least the early '50s. Rank's distribution arm was called General Film Distributors until then (can't remember the exact year, and I'm writing this from a hotel room in the US - will look it up when I get home). Films made during this period (1937 to early '50s) still feature the trademark Rank opening - the bronze, muscular looking chap with the gong who I guess Phil might take a shine to - but with 'GFD presents', or some such wording, rather than 'The J. Arthur Rank Organisation Presents' over it.
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Charles Greenlee
Jedi Master Film Handler
Posts: 801
From: Savannah, Ga, U.S.
Registered: Jun 2006
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posted 07-20-2006 08:57 PM
Nitrate film is usually on a celluiod substrate which is why it deteriorates so, right? I remember reading a few articles about plastics mentionioning that celluoid will break down into a flammable and sometimes explosive substance. Add Nitrate to the mix, in the for of the silver nitrate, can be nasty. Nitrate film has cause many many fires, particularly in storage warehouses. But Nitrate has also been used and stored, during its day, countless times safely. This would indicate that proper care, storage, and usage, would reduce the risks to almost nothing, like having a tank full of gas on your car. I wouldn't mind having it myself, but lacking the proper sotage facilities, and equipment to play it, I'd have to pass.
Oddly to note, back on my inital comment. Being that the pigment is Silver Nitrate, and having a substrate of possibly celluoid, is it possible that it can break down into Nitro-celluose? Which BTW composes gunpowder. Just a random thought, likd of like why do we drive on a parkway, etc etc.
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Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
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posted 07-20-2006 09:32 PM
quote: Charles Greenlee
Nitrate film is usually on a celluiod substrate which is why it deteriorates so, right?
Right. Cellulose nitrate film base is made by dissolving cellulose (wood pulp) in nitric acid and then processing the brew which results into a flexible, transparent solid. As you say, it's chemically very similar to gunpowder.
quote: Charles Greenlee
I remember reading a few articles about plastics mentionioning that celluoid will break down into a flammable and sometimes explosive substance.
Right. There are basically five stages of nitrate decomposition.
- Film shrinks slightly.
- Film becomes noticably brittle.
- Base becomes slightly sticky.
- Film becomes very sticky, with emulsion shrivelling off.
- Film becomes a congealed mass of sludge.
It becomes progressively more volatile (i.e. easier to ignite and burns more intensively once it is alight) as it progresses through those five stages. Up until stage 3 (sticky), the content can be rescued by copying to a polyester dupe (contact print if possible, optical print or scan/digital intermediate if it's too shrunk). Beyond that, the affected footage - not always the whole reel - is too far gone and there's no point in trying to preserve it.
quote: Charles Greenlee
Nitrate film has cause many many fires, particularly in storage warehouses. But Nitrate has also been used and stored, during its day, countless times safely. This would indicate that proper care, storage, and usage, would reduce the risks to almost nothing, like having a tank full of gas on your car. I wouldn't mind having it myself, but lacking the proper sotage facilities, and equipment to play it, I'd have to pass.
Again, right. Until the late 1980s, archives generally took the 'nitrate won't wait' approach (hence Anthony Slide's book of the same name) of believing that decomposition was imminent and inevitable, and that storing nitrate long term was a dangerous and unnecessary liability. Therefore, their policy was to dupe to acetate ASAP and then destroy the nitrate.
In the last 10-20 years, we've come to realise that this isn't wise, and for two reasons. Firstly, research at the Image Permanance Institute, Manchester Metropolitan University and other places has established that, given cool and dry storage conditions, decomposition can be inhibited at least for decades, and possibly for centuries. This paper from 1994 sets out the rationale. Secondly, copying technology is improving all the time. Contact printer heads now exist which can deal with up to 3% shrinkage in an original element, and HD digital scanning is getting cheaper all the time. If you conserve the original, you can always go back to it to make better dupes as the technology becomes available. If you dupe your original and then destroy it, then that dupe is all you have; and in the case of some photochemical preservation work done in the '70s and '80s, the quality wasn't great.
So, long-term temperature and humidity controlled storage for original elements coupled with duplication either for access or, if the element is actively decomposing, for preservation, is the way most archives are going these days. But, needless to say, storing a significant quantity of nitrate in one place has health and safety implications which need managing, e.g. ensuring that air handling plant is well maintained, that disaster management plans are in place etc. etc. All the evidence we have suggests that in a cool and dry environment, nitrate can be stored in comparative safety - but, obviously, providing and maintaining that environment takes resources and money.
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Charles Greenlee
Jedi Master Film Handler
Posts: 801
From: Savannah, Ga, U.S.
Registered: Jun 2006
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posted 07-20-2006 11:39 PM
Yeah, I was recalling all that from various memories, some old. I was really sticking my neck out, suspecting someone would gladly take it, finding some flaw in my post. Glad to see my memory and logic, even if just a curious thought, was sound.
Also, I suspect some sort of cellular storage contairers would benefiet the Nitrate film. Sealed in it's own container, better control over it, and if it does flare up, it's limited to just that container/can. Maybe ones with a smoke sensing unit, real small and cheap, rigged to a small Halon cylinder, like the size of a CO2 cartridge for a small BBgun. Film ignites, the smoke detector, in the small space, almost immediatly ignites, sets off the Halon, and puts out the flame. May even save the film in the can itself. Only problem with it, is I remember something about Halon working by displacing the oxygen, and since a Nitrate fire creates its own, that won't work. But I also remember them using Halon to put out fires with similar type, self-oxygenating, fires.
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Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
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posted 07-21-2006 06:47 AM
As you point out, it's the fact that a nitrate fire produces its own oxygen which makes the stuff so difficult to deal with. So if you have a fire in a sealed, airtight container, the chances are that the offgases are just going to increase the pressure inside the container until it explodes. There was a recent thread on another list I read which speculated that it might be possible to actually put out a nitrate fire once its established, if you could find a way to reduce the temperature in the atmosphere below the point at which combustion is possible; but as far as I know, no-one has ever attempted to design a fire suppression system which does this.
An added complication for us is that the use of Halon is now illegal anywhere in the European Union (though I gather it's still legit in the US), and has been since the end of 2003. The alternative, Ingergen, works: but at £10k for a cylinder of the stuff, many existing archives are having problems raising the money to upgrade their systems.
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