The Abbey Newsletter

Volume 18, Number 4-5
Aug-Sep 1994


Temperature & RH Guidelines Challenged by Smithsonian

Comments and Editorial by Ellen McCrady

A recent press release from the Smithsonian Institution [transcribed below] describes research that it claims invalidates previous environmental recommendations for maximum fluctuations in temperature and relative humidity in museums. It describes the currently accepted ideal conditions as 70°F and 50% relative humidity (RH).

(Actually, it is hard to demonstrate that there is a consensus on ideal RH. Of the ten published recommendations in my files, all from experts, only three give a single target figure for RH. Most of them give a range, typically 40-60%, from which to choose a value that will work for the building and collection under consideration.)

The new recommendations, based on research performed at the Smithsonian's Conservation Analytical Laboratory over the last year, allow "as much as 15% fluctuation in relative humidity and as much as 10 degrees Celsius [18°F] difference in temperature." It is not clear whether they mean these figures to represent the total range of variation, or the excursions on either side of the target figure, as is customary (e.g., "45% ± 5%"). If they mean the total range of variation, then it would be some figure ± 7% or 8%. If they mean the excursion from the RH target figure, they are suggesting ± 15%. Whatever the case, the press release says, "This new insight could save museums millions of dollars in construction and energy costs to maintain environmental conditions once considered essential for the preservation of artifacts."

These conclusions were announced at the American Chemical Society in mid-August. (The press release does not say whether this announcement was given in a paper or in a discussion.) The four researchers named are David Erhardt, Marion Mecklenburg, Charles Tumosa and Mark McCormick-Goodhart. Their work has always commanded respect. I have no reason to believe that it is less than excellent. So far, however, nothing has been published, except the press release.

On request, CAL sent a copy of the paper mentioned in the press release. The reference is: "Mechanical Behavior of Artist's Acrylic Emulsion Paints under Equilibrium Conditions," by M.F. Mecklenburg, C.S. Tumosa, and J.D. Erlebacher. ACS Polymer Preprints, v.35 no. 2, 1994, pp. 97-98. It reports an experimental study on stresses, moisture coefficients and so on for selected acrylic paints under varying conditions, but it draws no general conclusions about other materials.

The new recommendations are intended to apply to all materials, including wood, cellulose, fibers, photographic emulsions and pigments. They are said to be based on lab tests on the physical, mechanical and chemical properties of materials commonly found in museums. The reactions of complex objects were modeled by computer, using advanced software.

The press release emphasizes the sophisticated nature of the research on which these recommendations were based, but is silent on the subject of how it relates to previous research and experience. Perhaps the authors will go into this in future publications. Knowledge does not grow in waves, with each new advance superseding and invalidating all previous work, like waves on a beach. It grows like a building, as it must, with each investigator contributing his own brick or beam or shingle. And like a building, if something is not right, the offending construction must be removed down to the sound material on which new work will be based. Whenever new research appears to invalidate previous research, the burden of proof is on the author of the new research. Before it can be accepted, its validity must be demonstrated to the complete satisfaction of other researchers in the same specialty. In applied fields like conservation, it is important to seek acceptance from those specialists who make systematic field observations, as well as from those who work in laboratories.

This means that the first announcement of any important new conclusion or finding (except brief technical notes to establish priority) should be made to the appropriate professional group in writing, as well in oral presentation, and it should give enough technical detail to allow the reader to a) know exactly what is being claimed or announced, and b) evaluate the evidence on which the claim is based. Researchers who announce new findings should also review the work on which their research is based, and clearly distinguish their own contribution from what has gone before.

The ACS conference was not an ideal venue for an announcement with such far-reaching implications, even if it is later published in some appropriate journal. This is because the people for whom the work was supposedly done (the curators and conservators) were not there, and they had no way of knowing that such an announcement was forthcoming. I am not suggesting that advances in basic science should be announced first at museum or library conferences. However, this involves applied rather than basic science. The press release clearly implies that the work is most significant for those who will put the findings into practice, and that it is complete and ready to apply.

Curators and conservators will read in their morning newspaper that the environmental conditions they have worked to achieve in their collections appear to have been suddenly and without warning discredited by Smithsonian scientists. Who is their director going to believe? Will the director be patient and wait until all of the research behind this recommendation finds its way into print, and then until other conservation scientists and conservators have a chance to evaluate it in the major journals? Directors would rather listen to someone who says their advice will save them money than someone who says their advice will cost money. They will not reserve judgement; they will not ask their conservators whether there is any evidence that the new recommendations are valid, because they are not scientists and are not used to thinking that way.

It is hard to believe that the Smithsonian researchers, or their Public Relations Office, or both, forgot the lesson that the cold fusion flap taught the rest of the country, that publication by press release is inadvisable. Even though this situation is slightly different from the one at the University of Utah, the parallel suggests itself, and they would have been wise to avoid any comparison with that unfortunate incident.

Regardless of how the announcement was handled, if the research proves to be sound and useful in the end, we will be grateful. It is certainly needed. This topic has been badly neglected until now, probably because it is so complex: long-term as well as short-term effects on all sorts of artifacts have to be investigated. If the Smithsonian scientists have made a significant contribution, they will earn the gratitude of all who rely on environmental recommendations, and of other scientists who can build on their work.

The library preservation community has been asking for more environmental research for years. In 1989, the Preservation Administrators' Discussion Group put "cost analysis of the effectiveness of controlling environmental conditions to extend the life of books" at the top of their list of research priorities. Questions about environmental control guidelines come up at nearly every professional meeting in preservation and conservation. News about such guidelines were on the front page of the first two 1994 issues of the Abbey Newsletter, the first news item being the NARA guidelines and the second one a call for research.

The people who are responsible for collections, and who are wondering now what to make of this new information, may find answers to their questions if they go to the September IIC meeting, where David Erhardt and Marion Mecklenburg will give a paper entitled "Relative Humidity Re-examined." Because of the number of questions that the press release has raised, they may find that things will be up in the air for a while. There may be nothing to do but wait, and avoid drawing any conclusions until all the evidence is in. More presentations at professional meetings are planned by the authors.

The press release follows. n

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