THE IMPACT OF RESEARCH ON THE LINING AND CLEANING OF EASEL PAINTINGS
JOYCE HILL STONER
5 RESEARCH DESCRIBED IN VARIOUS PUBLISHED SOURCES
- Gustav Berger on lining adhesives
- Gustav Berger on effects of RH/temp/stress/strain
- Aviva Burnstock/Raymond White on cleaning methods and materials
- René de la Rie on varnish
- David Erhardt/Jia-Sun Tsang on cleaning methods and materials
- Robert Feller on varnish
- Robert Fieux on electrostatic hold linings
- Robert Fieux on lining adhesives and supports
- Gerry Hedley on lining supports
- Gerry Hedley on solvent parameters
- Elizabeth Jones/Nathan Stolow on solvent action and cleaning
- Marion Mecklenburg on lining supports
- Marion Mecklenburg on effects of RH/temp/stress/strain
- Bernard Rabin on lining adhesives
- Suction tables,, various researchers on design and use
- Richard Wolbers on cleaning materials
- Richard Wolbers on fluorescent staining media ID
- Other: please write in
In a second step, 140 copies of a questionnaire based on this list were sent to the Fellows and Professional Associates listed in the 1993 AIC Directory as specializing solely in the treatment of paintings. Information was gathered on respondents' preferences regarding lining adhesives and methods, coating identification and removal, and varnishing and how their preferred methods may have changed over the last 25 years. Familiarity with and impact of research were assessed by asking respondents to assign numbers between 1 and 10 for each topic. Thirty-two questionnaires were returned, for a response rate of 23%, a rate in a normal range and considered statistically acceptable. To guard against significant omissions, the questionnaire had two labeled spaces for “write ins.” Two respondents nominated themselves but each was a solo vote. Frantisek Makes and his enzymes used for cleaning received two write-in mentions. (Makes had not been considered as an English-language author). There were additional mentions of Bent Hacke, Vishwa Raj Mehra, Wieslaw Mitka, and Anthony Reeve (these researchers were meant to be included in “various” in the suction table category). Other write-ins occurred within the comment sections and will be mentioned later.
What was learned from the survey about current lining practices? Gerry Hedley had carried out an analogous survey, largely outside the United States, in 1984 (Hedley and Villers 1984). He reported a general move away from wax and a comprehensive embrace of Beva 371. At that time, the practices of the majority of U.S. paintings conservators might not have been tallied similarly. However, we now have reached parallel results. Chandra Reedy structured the respondents' number ratings regarding familiarity and impact into tables of data using a computerized statistical program. She calculated the ratio of impact to familiarity for each researcher to assess how much actual effect the research has had on those who filled out the questionnaire (table 1.).
TABLE 1 IMPACT/FAMILIARITY RATIO RANKING FOR LINING (top 5/6)
Thirty-one of the 32 respondents who specified lining adhesives, or 97%, currently use Beva 371 as one of their lining adhesives. A number noted they used exclusively Beva, and many gave the figure of 90% or above for choosing Beva when they must do a lining. In the two decades since its introduction, a change from 0% to 97% use is a clear signal of impact. Sixty-two percent of the respondents still use wax on occasion, but many noted that was 10% of linings or less. Fifty percent noted use of acrylic dispersions, often citing Lascaux products. Three respondents reported use of glue or paste on occasion, and two mentioned current use of Fabrisil. Rabin's poly (vinyl acetate) lining adhesive was listed often as a past preference but was not listed as a current choice by any respondent; several noted encountering problems with its brittleness. Bernard Rabin himself, speaking to the University of Delaware/Winterthur Art Conservation graduate students a few years ago, lined portions of a cut-apart painting with different adhesives, submerged each section in a bucket of water, and showed how poorly the portion lined with the PVA adhesive withstood the wetting. Many of his other students and protégés have witnessed Rabin's frank openness and desire to do what is best for the painting during his career of treatment and training of interns.
Reflecting the Mecklenburg (1982) or Hedley (1988) research noting the importance of high modulus or load-bearing lining supports, respondents mentioned fiberglass fabric, polyester, Tetko, Mylar, Lexan, or acrylic awning fabric as lining supports, and also padded backings or inserts with ragboard or ethafoam for loose linings. Respondents generally noted that the RH/temperature/ stress/strain research had been important in their thinking and problem solving. Although suction table research was listed as the sixth most significant topic, only three respondents specifically listed use of a suction table as one of their regular methods.
Nonlining was overwhelmingly the procedure of choice (90%), usually followed by strip linings, loose linings, and drop linings. Quotations included “within the last 12 years, I have changed from lining 75% of the time to nonlining 85% of the time,” or “I haven't lined a painting in 10 years.” Mecklenburg et al. (1994) reports more about his own research in this issue of the Journal; his research results have now taken a turn toward supporting many of these concepts of minimal intervention.
On Picture Varnishes and Their Solvents was originally published in 1959 by the Intermuseum Conservation Association in Oberlin. It was revised in 1971 and again in 1985. The research by these three pioneer authors—Robert Feller, Nathan Stolow, and Elizabeth H. Jones—continues to provide basic and useful parameters to paintings conservators for approaches to cleaning and varnishing (Feller et al. 1985). Ninety percent of the survey respondents use Acryloid B-72 as one of their varnish choices; Feller has published research on this resin throughout the last two decades.
When impact and familiarity for both lining and cleaning were combined and assessed statistically, Feller was number one, charted at .92+ and the comparatively recent work by René de la Rie was a close second at .92 (table 2). Since 1987 de la Rie has been publishing in ICOM and IIC preprints and journals on research regarding problems of picture varnishes, first at the Metropolitan Museum of Art and now at the National Gallery of Art. Sixty-one percent of the survey respondents use Tinuvin 292, Arkon P90, or Regalrez, materials de la Rie first discussed at the IIC 1990 Congress(de la Rie and McGlinchey 1990a). The use of these materials has gone from 0% to 61% in the last three years, as paintings conservators seek varnishes that provide optimum paint film saturation combined with acceptable aging characteristics. With or without Tinuvin or other stabilizers, 87% of respondents report using natural resin varnish. Most report that this use has been a more recent development as they seek saturation appropriate to the age of the painting. Feller and de la Rie have both reported less-than-excellent results on the aging properties of polycyclohexanones, but 51% of respondents still also use those varnishes for certain aesthetic effects on occasion.
TABLE 2 IMPACT/FAMILIARITY RATIO RANKING FOR COATING REMOVAL AND COATINGS (top 5)
In both lining and varnishing we seem to be in a postmodern period of conservation where many past materials are borrowed and used alongside newer choices. Two decades ago there was more reliance by an individual practitioner on one adhesive or one varnish. Now there is a more complex menu not only of adhesives or coatings but also of methods of application. It certainly makes both mastery and instruction more challenging. If one lines rarely and there are at least five adhesives to choose among for these rare occasions, in addition to alternative methods of vacuum, suction, drop linings, hand linings, or strip linings, it becomes increasingly difficult to develop or impart expertise in any one system.
Another recent researcher who was statistically charted in the top five for research in coatings and coating removal is Richard C. Wolbers, who has been publishing in AIC Preprints since the Vancouver meeting in 1987 and on the subject of cleaning since 1988 (Wolbers 1988). He has been invited to conduct small workshops in more than two dozen locations around the world in recent years, introducing conservators to alternative cleaning systems, many of which were based on his previous work in the field of biochemistry. These less toxic cleaning materials can often permit the conservator to distinguish and selectively remove unwanted discolored layers of animal glue, linseed oil, or resins from the surface of paintings, often without disturbing an underlying layer that might previously have been considered to be even more soluble. The majority of respondents noted that they still use traditional solvent testing methods to determine cleaning approaches, but some turn to resin soaps and solvent gels for difficult problems, noting their safety and effectiveness as soon as the principles of their action are understood. Some respondents mentioned a change toward thinning rather than removing varnishes.
Gerry Hedley's research on solvent action (Hedley 1980) was charted with high impact, and his work on attitudinal research and his videotaped lectures on the philosophies of cleaning received special mention (Hedley 1985, 1990). Hedley was one of the few researchers publishing in both areas of painting conservation with a calm, deadpan reporting style. The field is clearly the poorer since his death in 1990. A collection of 20 of his articles has just been published (Hedley 1993).
In addition to the attitudinal research by Hedley, respondents also mentioned the philosophical teachings of John Brealey, who worked at the Metropolitan Museum of Art from 1976 to 1989, creating lively discussions in the field with his statements regarding minimal intervention in lining and cleaning. His statements from the late 1970s, then considered controversial, have in many ways become standard operating procedures. Brealey did not write articles, but some publications are said to be forthcoming from his former students and colleagues.
Respondents were asked to note whether they felt our profession encourages invention and research. Lack of funding was often mentioned as a problem. Funding sources for independent researchers have diminished rather than expanded. The National Museum Act of the Smithsonian Institution supported independent research from 1972 until its demise in 1985. The Samuel H. Kress Foundation has supported research for more than two decades, including the work of at least two of the paintings conservation researchers cited above. Unfortunately, the Getty Grant Program, the National Science Foundation, and the National Endowment for the Arts do not currently have categories for support for research in conservation.