Volume 14, Number 2, May 1992, pp.26-27
Three conferences are reviewed in this column:
London, September 1991
Many WAAC members attended the international conference, "Art In Transit" in London in September 1991. Organized by the Tate Gallery (London), the Canadian Conservation Institute (Ottawa), the Conservation Analytical Laboratory, Smithsonian Institution (Washington), and the National Gallery of Art (Washington), the conference included 3 days of papers and, for a smaller group, a 2-day workshop at the Tate.
As the contents of the conference were outlined thoroughly in a front page article in the January 1992 issue of the "AIC News," there is little point in reiterating the topics discussed. I would like to point out to the membership that the printed material which formed the backbone of the conference is available at a very reasonable price by mail. Please write for information about these publications to:National Gallery of Art
As a conference attendee myself, I plan to present an introduction to the principles addressed at the conference, for SF MOMA's registrars and installation crew, as well as to Bay Area art handlers and shippers. I encourage my colleagues who attended "Art In Transit" to help disseminate the knowledge gained there by organizing similar presentations.Will Shank, Chief Conservator, San Francisco Mus. of Modern Art
Washington, DC, December 2-6, 1991
In December, the Conservation Analytical Laboratory of the Smithsonian Institution sponsored a 5-day workshop on the low- pressure suction table for textiles and paintings conservation. The course was organized by Tim Vitale, Senior Paper Conservator, and included presentations by 18 guest speakers. The schedule was planned around morning lectures and afternoon workshops. For a complete summary, refer to Carol Christensen's March article in the AIC News.
Thanks to Carol for her excellent and thorough reporting of the conference. Her work allows us the luxury of making either more general or more specific comments. The discussion here will be confined for the most part to aspects of paintings treatments only. We also wish to reiterate her praise for Tim Vitale and the conservators and scientists who acted as guides for the course.
The issues which emerged during the week were a result of how different approaches call for different features in the design of equipment. Jim Coddington, for example, pointed out that the NASCOR table, with a lateral high volume air-flow system and optional humidification from above, was well suited to the needs of the collection at MOMA. The types of problems common to modern paintings may require the use of synthetic materials combined with the application of high air-flow, and humidification must be kept to a controlled minimum. Tony Reeves, on the other hand, described the advantages of an internal humidification system featured by the Willard which can simultaneously sustain a level of humidity to the reverse of an object while at the same time restraining it under suction. Bent Haacke expressed his view that a technically sophisticated table is unnecessary for most effective treatments. As an important early leader in the development of low-pressure suction techniques, Haacke has focused his work on a basic table design capable of accommodating the use of both traditional and more modern materials in treatment. The table incorporates high air flow and heat, while the component of humidity is usually introduced from below via a damp cloth.
Some of the important questions that were dealt with involved lateral vs. downward flow, humidity from above vs. humidity from below, and local vs. overall treatment. Afternoon workshops provided opportunities to compare the performance of table design in the context of treatment. Here specific problems were addressed, such as differential drying, the monitoring of humidity levels and the important role of interleaves.
An interesting debate developed regarding methods of humidification for the reduction of planar distortions and cupping of paint. Options presented ranged from: large chambers with "actively" maintained RH levels via humidifiers, steam, etc; humidification from below through damp cloths or RH controlled air channels; "passive" RH maintenance via water trays or salt solution; or combinations of the above for periods of from 10 minutes to 6 hours, often with the simultaneous or subsequent use of heat, at various temperatures. (In the interest of completeness, one must also include the lightly misted blotter underneath the painting for one to two days followed by low levels of heat and suction technique, which was not a method presented, but which is favored by a number of conservators.)
The obvious and interesting fact is that all of these variations are working, in that they are doing something that is considered effective by the conservator. It is also obvious that our "craft wisdom" is way ahead of our understanding of what these treatments are actually doing, either chemically or mechanically, to the painting laminate structure.
Marion Mecklenberg's work, presented at the conference and reported in "Art In Transit," does address some of these basic research issues. Marion's evidence indicates that the rate of diffusion of moisture into oil paint films of moderate thickness at room temperature is relatively slow, on the order of one to two days, subject to variation due to a number of factors. He therefore felt that relaxation of a paint film after a brief humidification with heat was more likely to be the result of the heat applied.
Probably the most intriguing and disturbing information, however, was his reporting of the damaging effects of chilling and desiccation on various painting materials, the kind of chilling that can occur with environmental changes, solvent evaporation and the rapid cooling possible when using suction. This research cannot be done justice in a synopsis. It's "must" reading and worth it. (If you want a running start, read his 1982 paper, "Some Aspects of the Mechanical Behavior of Fabric Supported Paintings.")
The lining techniques demonstrated were fairly straightforward, with some emphasis on the benefit of being able to line with a membrane over the image area. It was disappointing that little was said about cold linings. It would seem that the present techniques have not proved satisfactory to many who have tried them and not much work is going on in research. (A cold lining that could be done on a suction table with no covering membrane would be a much appreciated technique. Alternatively, a suction table with a heat source, such as carbon fabric, which allows very, very brief heat exposure would be a useful development.)
The low-pressure suction table, however, clearly offers conservators a range of versatility unavailable in conventional hot tables. The advantages of suction allow conservators to work within lower ranges of temperature and humidity with successful results. Future workshops will hopefully address the question of a more effective control and monitoring of humidity and a more efficient method of internal heating that is compatible with high air flow.Virginia Rasmussen, Paintings Conservator, Los Angeles County
Most textile conservators have approached suction treatments by having to adapt tables and/or disks which have been developed for use in other disciplines, notably paintings and paper. This fact was reflected in the talks presented, which featured a wide range of "craft" solutions dependent on the equipment available to the conservator at the time. This is perhaps best illustrated by the week long debate that centered around the use of Michalski's hacksaw blade PVC elbow versus Vitale and Ashton's Japanese fritted disk. Both systems are used for localized cleaning and stain removal. The difference between them is that the hacksaw blade system operates with high air flow while the fritted disk works by capillarity, using a system of blotters. Mary Ashton presented a successful case history using the Japanese disk, and Mary Kaldany spoke about her success with the hacksaw blade device. Clearly it is possible to develop techniques which work for most equipment available, but textile conservators are not at the stage where we are able to create a clearly focused set of specifications for equipment of our own.
An interesting issue which arose during the lab practicals is the different way in which textile conservators use suction equipment. Compared to paintings and paper, textile treatments involve large quantities of liquid. In fact, the only crack in Tim Vitale's cool and calm facade occurred as foam was observed shooting up the clear vacuum hoses on its way to his pumps. One of the most useful features for a textile table was generally agreed to be a very large trap.
As textile conservators build up experience using suction equipment, we are becoming more sophisticated in our choice of treatment options, and these may well relate to the specific job we expect our equipment to do. Fonda Thomsen's experience with adhesive treatments was fascinating in this respect: lateral air flow pulls more adhesive through a textile than downward flow, and I can imagine circumstances in which each situation would be desirable.
I think it would be fair to say that the paintings conservators' demonstrations and experiments were more focused than ours. The reason, I believe, is that textile conservators have not yet clearly defined the set of problems that we are looking to different types of suction equipment to solve. According to Stefan Michalski, the technical literature from the dry cleaning industry, an obvious source of information for us, is not very helpful. So, in conclusion, that oft-repeated refrain of the conservation literature appears here yet again--more work needs to be done.Linda Eaton, Textile Conservator, Winterthur Museum,
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