Film-Tech Forum ARCHIVE: Has anyone tried this:Vinegar Syndrome Cure

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Posted by Don E. Nelson (Member # 1049) on 08-07-2002, 01:37 PM:

I have been reading a lot about vinegar syndrome, (as I have one feature that suffers badly from this malady.) All 6 reels of this feature are currently stored on cores in air tight plastic tubs, with molecular sieve material, in a dark, low temp, low humidity room. I was pondering about other cures and was wondering if anyone has tried this procedure on vinegar syndrome prints, in an attempt to slow down the film deterioration process. Before I try this intricate procedure at work, I am looking for feedback.
OUTGASSING PROCEDURE:
Rewind the infected film onto a core, and put it into a vacuum chamber, seal the camber and pump it down to at least 1 X 10-3 torr or 1 micron, valve off the the roughing pump, backfill the chamber with an inert gas, argon, nitrogen, etc, repeat this pump-down/up to air process 3 or 4 times to thoroughly remove all the existing outgassing gases, (1 micron pressure should be more than adequate (viscous flow region) as opposed to punping the film down into the 5th or 6th range (molecular flow regine)

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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...more signal, less noise!

Posted by Jeff Taylor (Member # 443) on 08-07-2002, 01:44 PM:

I'm not sure I follow your suggested process, Don, but for those of us who want to access our prints the best procedure seems to be 1) ventilate, ventilate, and ventilate some more, 2) clean the print frequently and well to remove any traces of accumulated acetic acid (Film Guard works GREAT), 3) rewind them frequently and store alternatively in heads out, tails out format so the whole thing breathes well, and 4) store them AWAY from any unaffected prints. I have found that prints with just a hint of the onset of VS either go years without any further deterioration if treated this way, or in some cases seem to cure themselves. Badly deteriorated prints are a lost cause--show 'em until they won't run and throw them away.

Posted by John Pytlak (Member # 331) on 08-07-2002, 01:58 PM:

Many years ago, there was a proprietary film treatment known as "Vacuumate" that put film in a vacuum chamber to imbibe chemicals (Tradename of "No-En Film Treatment") into the film roll.

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

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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

Posted by William Hooper (Member # 71) on 08-08-2002, 12:44 AM:

Last year in the SMPTE Journal there were at least two articles about VS, one was about storage cans. As mentioned, ventilation is most important, & you can see the results of some different designs.

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.

Posted by Leo Enticknap (Member # 534) on 08-08-2002, 02:25 AM:

The thinking among archivists about this is broadly that there are pros and cons between sealing and venting an element and that a number of factors need to be considered when deciding which option to take.

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.

Posted by Alex Grasic (Member # 1371) on 08-08-2002, 02:44 AM:

I hate to sound like a rookie but what is this syndrome that you are talking about curing?

Posted by Leo Enticknap (Member # 534) on 08-08-2002, 03:23 AM:

Deacetylation, sometimes called vinegar syndrome, is a chemical reaction which affects all film produced on a cellulose acetate base. It's called vinegar syndrome because that's what an affected film element smells like.

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.

Posted by David Rigby (Member # 1301) on 08-08-2002, 04:01 AM:

Anyone else think it's ironic that an inert base wasn't developed until film production reached a stage where most of the product isn't worth saving anyway?

Doh!

David

Posted by Leo Enticknap (Member # 534) on 08-08-2002, 04:23 AM:

Yes, but then they invented 'digital cinema'

so what goes around comes around!

Posted by Jeff Taylor (Member # 443) on 08-08-2002, 07:43 AM:

I've mentioned this point in the past, but it may be worth repeating in this context. Leo points out the shrinkage which occurs over time in all acetate prints, but is far more pronounced in films afflicted with VS. This shrinkage generally contributes to cupping and ribboning. These prints will chatter, resist pulling a good, even focus, won't take up properly, and ultimately will be unrunnable. I have found that a liberal application of Film Guard combined with a tight reverse wind can have a dramatic impact on these prints by relaxing the cupping and ribboning. Give it a try and you will be amazed. ...just my $.02.

Posted by John Schulien (Member # 215) on 08-08-2002, 02:36 PM:

I've been mulling over a different approach ...

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?

Posted by Jeff Taylor (Member # 443) on 08-08-2002, 02:43 PM:

ASSUMING that you could bond another polyester base to the emulsion, which seems like a stretch, and ASSUMING you could disolve away the acetate base without destroying the emulsion, another stretch, wouldn't the emulsion have shrunk along with the old base sufficiently that you'd have to mask the hell out of it as it would no longer line up with the frame lines? It's hard to imagine what print would have sufficient value to invest this kind of time when the archives can't even afford to keep up with transfering all the deteriorating nitrate out there onto safety stock. Am I missing something?

Posted by Leo Enticknap (Member # 534) on 08-09-2002, 01:13 PM:

I agree. Separating the emulsion layer from a decomposing base is done by conservators of still negatives on nitrate, though I'm not sure about the chemistry involved. I think it would probably be impossible to do this with movie film, at least to bond the extracted emulsion to a new base with conventional 35mm dimensions and then use conventional printers to copy it. It might be possible to digitally scan an 'extracted' emulsion layer or use a specially designed step printer to copy the frames, but AFAIK no-one has ever seriously tried to do this.