Leave the film in this inert gas atmosphere for 24 hours, Remove the film from the chamber, and immediately put in an airtight sealed plastic bag and store in a low temp./low huimidity storage room. After 24 hours use the most sensitive detector for acetic acid, your nose , and determine if there is an apparent slow down in the outgassing of the film. Any ideas woiuld be appreciated on refining this technique. Thanks

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Molecular Sieves actively adsorb both excess moisture (which initiates the degradation of the film base) and acid vapors from the film in a sealed storage container:
http://www.kodak.com/country/US/en/motion/support/technical/molecular.shtml
http://www.fpcfilm.com/US/en/motion/FPC/fpc/mole.html

Sealing film was not recommended, because Mr. Acetate Ion leaves his happy home & starts promiscuously combining like something out of a country & western song with the H20 in the air, on the film, & in the emulsion, acetic acid forms, & it ramps up a curve to autocatalysis very quickly when sealed. I don't know what argon, etc. would do for you there.

As William and Jeff point out, the big problem with sealing is that you are potentially sealing the acetic vapour in with the film element, thus increasing the concentration of gas as the decomposition continutes, which in turn accelerates the speed of the chemical reaction which causes the decomposition. When the atmosphere inside the sealed container reaches an acidity level of pH 4, the element is at risk of becoming 'autocatalytic'. This means that, just as burning nitrate generates the oxygen needed to sustain combustion, the deacetylating acetate stock will release vapours with a sufficient acid concentration to accelerate the rate of decomposition.

There are two ways to inhibit decomposition inside a sealed container: molecular sieves, as described by John, and secondly by storing the element in such a cold and dry environment (deep freezing it, effectively) that the chemical reaction is so slow that in effect you have decades, if not centuries, before the autocatalytic point is reached. The latter really isn't an option for all but the richest archives due to the sheer cost of maintaining those atmospheric conditions. We certainly couldn't afford to do that.

Storing an element in vented cans has one huge advantage: the acidic vapours produced by decomposing film disperse from the can, thus keeping the acidity level in the container low and therefore prolonging the time left before the element becomes autocatalytic. There are three drawbacks. 1: As the acetic acid leeches out of the film base, the stock shrinks more quickly, it becomes drier and more brittle, which makes it more difficult to print/project/telecine or whatever. 2: If you have lots of elements in different stages of decomposition all in the same vault, there is a risk that the fumes given off by those in an advanced state of decomposition will affect those still in a better condition. For this reason many archives will place good quality acetate elements in vented containers and then transfer them to sealed ones with molecular sieves when the elements go autocatalytic. 3: Maintaining constant temperature and humidity isn't enough: you also need a constant airflow and filtration in your air handling system in order to get the acid out of the atmosphere, which again increases the cost of maintaining a vault.

If I understand the procedure described by Don correctly, what it basically does is to force all the latent acetic acid vapour out of a film element under extreme pressure. Whilst this might work as a temporary solution enabling a film to be printed over a short time-frame, my reservations with this would be (i) the shrinkage and brittleness problem would certainly remain and could be exacerbated, and (ii) the hardware and consumables needed for this procedure sound mighty expensive.

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When acetate film is manufactured, wood pulp is dissolved in acetic acid in order to form the cellulose base. Lots of very clever manufacturing stages later, this brew becomes the tough, flexible and transparent material needed to support the emulsion and to withstand being passed through the mechanism of a camera, printer or projector.

The problem is that the acetic acid is still there in the base, and it starts attacking other chemical elements with the result that very slowly, the film starts destroying itself. This process happens in all acetate film and it starts happening from the moment the base is cast. However, it is extremely slow and can be made even slower by storing the film in an atmosphere with low temperature and humidity. But even stored in completely the wrong conditions, acetate film will still be usable for at least 15-20 years after it's made, so vinegar syndrome really isn't much of an issue as far as release prints are concerned. It is an issue, however, if you're trying to preserve an acetate film element long term. Therefore film archives, which preserve original negatives and other master material, have been trying to find cheap and efficient ways of controlling the rate of this chemical reaction, as have private film collectors who hold acetate prints in their possession.

As you will have gathered by now, there is no easy answer. It's a problem that can be managed, but not solved.

Cellulose nitrate film (in which nitric, rather than acetic acid is used), in mainstream use from 1889-1950 approx., is not affected by vinegar syndrome, but it is subject to other chemical processes that cause decomposition which are just as difficult to manage. Acetate was in mainstream use for release prints from 1948 until the early '90s. The film stock used in cinemas now is polyester, a synthetic base which is not affected by vinegar syndrome.

Doh!

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Cement, paint on, form, or chemically bond a new polyester base to the emulsion side of the film, then dissolve the decomposing acetate base in acetone.

Anyone heard of any research along those lines?

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