I have a reply from Bill Hollinger at Conservation Resources that clarifies some of the issues raised in this thread. It has a long section on the use of MicroChamber paper to preserve paper artifacts, so I don't want to quote it in full. (I'll send an unedited copy to anyone who wants it via PM.) But several parts are worth quoting and commenting on.
Dear Dr. Ellis,
We checked and we do not see a Bags Unlimited in our customer base. MicroChamber is our trademark and it is patented.
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Sensei comments: The product sold by Bags Unlimited is unambiguously the product of Conservation Resources. It bears the firm's watermark with it's name, logo, and patented trade name MicroChamber. But it's likely that they do not do business directly with Bags Unlimited, but sell in bulk to a middleman, who then sells lots to BU. That said, the rest of the letter does express some of the caution that the BU rep. expressed to Matt.]
If acetic acid is the cause of the problem you describe, MicroChamber paper may be worth trying, because the specialized zeolite (SPZ) we developed does remove acetic acid as well as the aldehyde precursor to acetic acid. It may also be plasticizers are a problem too, so as always the wisest thing to do is contact a conservator with experience in this area to see what your preservation options are.
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Sensei comments: That's a little more positive than the report Matt relayed, in that the Conservation Resources people don't think that their product would actively harm cels. In fact, the paper passes the PAT (Photographic Activity Test) so it will not negatively impact the medium (cellulose acetate) on which the cels are painted. However, Hollinger is careful to note that their product will help IF vinegar syndrome is involved. If the damage is caused by some other form of plastic instability, such as a reaction to or with the plasticizer added to the plastic sheet used for the cel, then perhaps some other strategy would be better. In that case it would be better to consult someone who knows more about cels than the Conservation Resources experts.
Hollinger then explains that MicroChamber paper was developed to deal specifically with issues dealing with preservation of paper, which was attacked not only from within by acidic substances added during papermaking, but also from without by environmental pollutants. He concludes:
Microchamber products provide another tool for conservators, like buffered paper and temperature and humidity control. The causes of deterioration are many and varied, and the tools people use to lengthen the useful life of an artifact should not be seen as a guarantee they will prevent further deterioration, but rather as something with the potential to help in this regard.
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Sensei comments: This is the way that I took the statement made to Matt that the company would not consider itself liable if a cel became seriously damaged even when MicroChamber paper was used to protect it. It should be considered as one among several prudent measures in storing such products, and not as a "silver bullet" safeguard.
Hollinger then calls attention to a published interview with Dr. Jim Druzik, senior scientist at the Getty Conservation Institute (which is partnering with Disney to establish clearer procedures for storing cels archivally), in which he states that the material used in MicroChamber products took up acetic acid and retained it more tenaciously than any other material tested, even "during influxes of high humidity." However, Druzik was working with photographs and works of art on paper, not cels. (This is a .pdf file that I can pass on in a PM to anyone who wants it.)
He also recommended that I contact a professional conservator at the National Gallery of Art (which I will do) and also gave links to
the Northeast Document Conservation Center and to
American Institute for Conservation of Historic and Artistic Works. Probably the
GCI–Disney Collaboration would also be worth contacting.
This doesn't get us far, but it at least clarifies the potential role of MicroChamber paper in the archival process. Is it essential? Probably not, if the cels are being stored in controlled conditions and aired out regularly. Will it prevent vinegar syndrome or other serious forms of deterioration? By itself, probably not. But, Hollinger thinks, it would have the beneficial effect of picking up and neutralizing acetic acid both from the cel and also from the outside environment. That in itself won't stop the inevitable process of chemical activity in the cel material, but it wouldn't hurt to use it, and it would have the potential to help prolong its useful life.
I'll need to focus on the cel contest for awhile, but I don't mind if others follow up these leads and report back what they learn.