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FACTS
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WOOD PICTURE FRAMES
David Grattan (1997) Courtesy of FACTS
We have been seeking research on the implications of using wood picture frames. Thus far, we have received the following information from Dr. David Grattan, Research Scientist at the Canadian Conservation Institute (CCI).
"I must confess that I know very little about the issue of wooden frames and the effect on materials in contact. However, the information that I have seen suggests strongly to me that unprotected wood is a hazard to cellulosic materials in contact. There is plenty of evidence that acetic acid is released, and many woods release other kinds of volatile molecules. I attach an article by Sakuno et al.—which shows the devastating effect of western red cedar emissions on the drying of oils—as an example. Another recent article reported on the emissions of old books (Buchbauer et al. Journal of Pulp and Paper Science, 21, no. 11 pp. J398-400 (1995).
Recent work on the accelerated aging of paper shows that if trapped, the volatile degradation products increase the degree of degradation and accelerate the rate. I do not necessarily think that wood and paper share all the same degradation products but it is a safe bet that there is some commonality. So I tend to agree with those who believe in sealing wood—and I also believe that use of metallic frames is probably the most secure approach—but it may not be absolutely necessary. It is a diffusion problem—if the diffusion of the volatiles is faster than the rate of reaction (or rate of absorption) then there is a little problem.
There is information in the literature about the rates of diffusion through various types of coating so your could probably make a selection—however, no resin is an absolute barrier to volatiles—diffusion rates are finite—and there is the added problem that barriers applied to one surface and not the other may stress the wood.
My solution to the problem would be simpler. I would line the rabbet with aluminum foil—or perhaps heat seal on a layer of an aluminum containing barrier film such as the Ludlow Corp. products. (Aluminum is essentially impermeable—provided that there are no pinholes.) This has the added benefit of avoiding calculations on the rates of diffusion!”
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