From: Larry Urbanski (email suppressed)
Date: Wed Aug 13 2008 - 19:38:24 PDT
Vinegar syndrome is indeed contagious in a storage environment. I think
this is where the rumor about film projectors and vinegar prints comes
about. These are two different things.
In the storage of films, the vinegar prints should be segregated. The acedic
acid off gassing in the vinegar prints can trigger vinegar in "good" prints.
Here is a study posted on another forum that clarifies this.
Larry
Urbanski Film
> Date: Mon, 18 Sep 2006 10:44:35 -0400
> Reply-To: Association of Moving Image Archivists <email suppressed>
> Sender: Association of Moving Image Archivists <email suppressed>
> From: D NISHIMURA <email suppressed>
> Subject: Vinegar virus Content-Type: multipart/alternative; Since
> we've been mentioned many times in this thread and I don't see any
> messages from Jean-Louis, I guess I'll have to say something.
>
> Back in 1991 we looked at what was known, then, as "infectious
> behavior," although it has been pointed out in this thread that it's
> only the catalyst (or accelerator) that is being spread and not the
> root cause of the deterioration (humidity and the characteristics of
> the cellulose acetate support.) In the first test, we interleaved
> fresh film with degraded film using polyester web as a porous
> interleaving material (so the films were not in direct contact.)
> Stacks of sandwiches of fresh/degraded film were bagged and incubated
> for up to 12 days at 90 C/50% RH. (Since we were in sealed bags, the
> films were all preconditioned to the desired water content before
> bagging.) Degraded film dropped in acidity during the first day from 6
> to 3 while fresh film rose in the same period from
> (approximately) 0 to 2.5. The acidity was titrated and measured in
> equivalent mL of 0.1 Normal (or Molar) sodium hydroxide per gram of
> film. It's not the amount of sodium hydroxide required to neutralize
> the acetic acid. The salt formed is sodium acetate that has a slightly
> alkaline pH. So it is the amount of sodium hydroxide required such
> that all of the acetic acid becomes sodium acetate.
> The acidity of the degraded and undegraded films then rose rapidly in
> paralell (more or less) such that the initially undegraded film hit an
> acidity of about 9 at the end of 12 days. A similar package of
> undegraded film (only) reached the critical point (0.5 acidity) after
> 10 days and got to about 1.75 at the end of 12 days. The experiment
> was repeated four more times just to make sure that we didn't have a
> fluke or an anomoly. The five experiments clearly showed the rapid
> adsorption of acetic acid by the fresh film (dropping the acidity of
> the degraded film and raising the acidity of the fresh film) and the
> subsequent rapid deterioration of the fresh film.
>
> In a second study, acetate film was put into a desiccator jar that was
> then filled with acetic acid vapors. THe film was left for two weeks
> at 70 C/80% RH. What we found in this experiment was that the acidity
> taken-up by the film was directly proportional to the acetic acid
> vapor concentration in the desiccator jar. Some deterioration may have
> taken place in the incubated film altering the film acidity and the
> acetic acid concentration in the jar, but not enough to make our
> experiment too noisy (although we only tested three levels of acetic
> acid vapor concentration.) In a third, related, study, triacetate base
> was exposed to 20 ppm acetic acid for 34 days at 38 C/80% RH. Base
> acidity went up from 0.08 to 0.8 and there was a slight loss of
> tensile properties.
>
> A fourth experiment was done in which triacetate film was exposed in a
> vessel (desiccator jar) containing glacial acetic acid for two weeks
> at 38 C/50% RH. During that time, the acidity of the film went up to
> 1.9. It was then incubated for two weeks at 90C/50% RH and the loss in
> tensile break stress was greater than that of the control that hadn't
> been exposed to the initial acetic acid fuming. THere is ample
> evidence that acetate film and base will adsorb acetic acid vapors
> from the air. The amount of adsorbed vapor is proportional to the
> concentration of acetic acid in the air. The adsorption of acetic acid
> by film results in an acceleration of the rate of deterioration.
>
> So there is the lab evidence for the so called infectious effects of
> deteriorating acetate film on "good" film, although it isn't truly
> infection in the sense of spreading of the root cause (not like
> spreading the small pox virus), but simply accelerating the
> deterioration rate of the film. Will two films in the same can behave
> differently? Of course they can. There are so many factors that will
> affect the observed rate of deterioration that it could be the rule
> rather than the exception. Do we know that the two films shared
> exactly the same history from processing on? Probably that's the
> biggest factor. However, we still run into the odd mystery film that
> would probably be explainable if we knew absolutely everything about
> the film. However, in the medical analogy world, I would consider them
> to be like the 93-year old, two-pack a day smoker who has apparnelty
> been smoking for 78 years and who eventually dies from being run over
> by a bus. In spite of all the evidence that says that they should've
> died from smoking-related diseases long ago, they keep on going.
>
> As far as metal surfaces go, they don't tend to adsorb (or absorb)
> acetic acid enough that I would be concerned about wiping them down.
> In addition, whatever might be adsorbed will come to equilibrium with
> the acetic acid concentration in the air so unless you're working in a
> fairly contaminated atmosphere, whatever might have been adsorbed by
> the projector should come to equilibrium fairly quickly with the
> relatively clean air (reducing the adsorbed concentration to pretty
> close to zero). I would similarly expect that if you could turn a
> glass vinegar bottle inside out, that pretty soon after the liquid had
> evaporated (mostly water), the amount of acetic acid found on the
> glass surface would also be close to zero.
>
> So there is what IPI has done specifically with regard to looking at
> the viral part of vinegar virus. It is documented in Final Report to
> NEH, Grant PS-20445-91, "New Approaches to Safety Film Preservation,"
> published in April 1994.
>
> -Doug Douglas Nishimura
>
> Senior Research Scientist
>
> Image Permanence Institute
>
> Rochester Institute of Technology
We will be closed September 9th until September 15th. Please note this on
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Larry Urbanski
708-460-9082
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_____
From: Experimental Film Discussion List [mailto:email suppressed]
On Behalf Of amanda christie
Sent: Wednesday, August 13, 2008 8:24 AM
To: email suppressed
Subject: vinegar syndrom contagion
>Vinegar syndrome is not like a virus. It is not contagious to "good" films
>if a "vinegar" film is run in the projector.
Is that true? Can others on the frameworks list confirm this?
i've always heard that vinegar syndrome was indeed contageous... and i just
did a quick web search now to see if i was crazy.... and all the sites that
came up in my search said that it was in fact contageous....
i've also always been told that you should never use the same equipment for
vinegared film as for clean film.... and that too came up in my web
search.....
i didn't find any evidence to the contrary... but i would happily be proven
wrong....
who else on the list has experience with vinegar syndrome and can give their
own experiences with it's either being contageous or not.... and whether or
not it's okay to use the same equipment as for clean film.
amanda
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