THE IMPACT OF RESEARCH ON THE LINING AND CLEANING OF EASEL PAINTINGS
JOYCE HILL STONER
ABSTRACT—Artists have been engaged in the restoration of paintings since antiquity. Coincident with the decline of intensive apprenticeship training of artists in the late 18th century, public controversies emerged regarding the cleaning of paintings. Scientists such as Michael Faraday and Max von Pettenkoffer began research efforts regarding art treatment techniques in the 19th century, which broadened with the 20th-century founding of national and international institutes for the coordination and improvement of conservation knowledge. Published material had first been focused almost exclusively on the care of easel paintings. The author traces the history of articles on this specialty and discusses the impact of published research on current lining and cleaning approaches. A 1992 survey of Fellows and Professional Associates of the American Institute for Conservation of Historic and Artistic Works engaged solely in paintings conservation investigated the areas of published research that have had the most impact on actual practice and documented that most respondents have significantly changed their approach over the last two decades, do not line paintings as often as they once did, and tend to follow a more minimally interventive philosophy.
In the early 19th century, Sir Humphry Davy studied the pigments of antiquity. His protégé, Michael Faraday, noted the need for employing a chemist in museums and carried out tests in the 1850s on the protective value of varnishes to prevent lead white from turning black after exposure to sulfur compounds released by trains and gas lamps. In 1870, Professor Max von Pettenkoffer published results of his experiments with the use of alcohol vapors to regenerate clouded varnish films. In 1920, Edward Waldo Forbes, director of the Fogg Art Museum, Harvard University, wrote about the need in the United States for the scientific study of the chemistry of paintings. In 1930, at the International Conference in Rome, “the scientific methods employed for the examination and conservation of paintings” were discussed (International Museums Office 1940). George Stout, head of the Department of Conservation at the Fogg from 1933 to 1947, noted that the Rome conference of 1930 “seems to have occurred at or near the end of an indefinitely long period of complacency with respect to the conservation of works of art,” during which the field had been merely a trade with tricks and secrets (Stout 1964, 126). Under the leadership of Forbes, Stout, and Rutherford John Gettens, then chemist at the Fogg Art Museum, the first technical journal in conservation, Technical Studies in the Fields of Fine Arts, was published from 1932 to 1942 by the Fogg Art Museum, with an international board of editors. Stout credits the “movement of large collections into emergency repositories” during World War II with drawing additional scientific, museum-based focus on problems of environment and transport (Stout 1964, 126).
Until at least this point, the history of paintings conservation and the history of conservation were essentially the same. The first use of the term “conservation” has been traced back to at least 1870, to Manfred Holyoake's book The Conservation of Pictures. Sheldon Keck noted in his presentation on the history of conservation at the annual meeting of the American Institute for Conservation (AIC) in Dearborn, Michigan, in 1976, that the restoration treatment of paintings dates back to Greek and Roman times, when it was in the hands of the artist-craftsperson. This tradition continued through Peter Paul Rubens, who treated a collection of paintings damaged by moisture in the 17th century (Keck 1976). Treatment by artists was fairly acceptable, as artists had generally had extensive apprenticeships and were required to understand their materials and the detailed construction of works of art.
2 THE ROLE OF CONTROVERSIES
By the end of the 18th century (coincident with the breakdown of extensive, requisite guild or apprenticeship training of artists) the cleaning of paintings began to cause public controversies, which continued across Europe throughout the 19th century. Attacks were made, moratoriums suggested, and commissions appointed in the early days of the Louvre (1790s), the National Gallery, London (1840s–50s), and the Pinakothek in Munich (1860s) (Keck 1984). Advances often follow controversy in many fields.
When the physicist Pettenkoffer proposed his alcohol vapor and copaiva balsam method for regenerating old varnishes in 1863, he hoped this method of minimal intervention would make the need for cleaning obsolete (Keck 1984). The Pettenkoffer method did reduce the number of cleaning controversies during the following 50 years but may have caused undue interaction between paint films and overlying varnishes (Schmitt 1990).
Cleaning controversies crossed the Atlantic Ocean to the National Gallery of Art in Washington, D.C., in the 1970s, and the most recent controversy with passionate press coverage involved the removal of glue and soot from the ceiling of the Sistine Chapel. New methods for formulating cleaning solutions for easel paintings have been published by Richard Wolbers (1988, 1990) and additionally tested by other researchers (see Burnstock and Learner 1992)s.
The lining, or placing of an additional backing fabric against canvas paintings, had not been a matter for public debate until some press attention was focused on this issue following a moratorium on lining declared during a conference at the National Maritime Museum in Greenwich, England in 1974 (Percival-Prescott 1976). The issues were further discussed at the International Council of Museums (ICOM) Committee for Conservation meetings in Venice in 1975, and at another conference on the subject in Ottawa in 1976, which produced a useful bilingual greencovered paperback collection of articles reassessing the lining of paintings (Ruggles 1976), reprinting many of the earlier papers and adding new ones. This focus on the drawbacks of lining was largely coordinated by Westby Percival-Prescott, who reminded conservators that lining a painting places it in a lining cycle or continuum from which it is difficult to escape (Percival-Prescott 1976).
Percival-Prescott took a leadership role and encouraged papers on nonlining approaches or alternatives to traditional wax lining from Gustav Berger, the inventor of the ethylene vinyl acetate adhesive, Beva, which was first introduced in the early 1970s (Berger 1976); Vishwa Raj Mehra, who launched interest in acrylic dispersion lining methods (Mehra 1975); and Robert Fieux, who invented both a new silicone adhesive–Teflon lining fabric, Fabrisil, and a new electrostatic hold system as an alterative to vacuum pressure (Fieux 1976, 1978). Bernard Rabin had published his use of a poly (vinyl acetate) lining adhesive as an alternative to a wax-resin adhesive at the International Institute for Conservation (IIC) Meetings in Lisbon in 1972 (Rabin 1976). Berger and Mehra also discussed and presented suction tables or vacuum envelope systems at IIC, AIC, and ICOM meetings. Suction tables were further developed by others including Bent Hacke and Wieslaw Mitka of Denmark, William Maxwell, Anthony Reeve, Marion Mecklenburg, and his brother Peter Mecklenburg. Many of these materials and approaches are still actively used, and some have been tried and superseded.
3 PAINTING, “THE QUEEN OF THE ARTS”
Why was so much of the early history of conservation entirely focused on the treatment of paintings? From Leon Baptista Alberti in the 15th century through Sir Joshua Reynolds in the 18th century, painting was considered “the queen of the arts.” Reynolds discussed a hierarchy of genres within painting that persisted at least through the first half of the 19th century. History painting or grand manner portraits in oil were the highest pursuits for an artist, whereas still life subjects or modest media such as watercolors were considered more suitable for women and other amateurs. In the tradition of Reynolds, paintings conservators were most prominently featured in historic controversies, established most of the early conservation laboratories, and generally ran the conservation organizations. The 1930 conference in Rome and its subsequent published manual (International Museums Office 1940) were concerned only with the treatment of paintings (fig. 1). The 10 volumes of Technical Studies in the Fields of Fine Arts published from 1932 to 1942 contained 79 articles, of which 55 (or 70%) were about examination, care, and treatment of paintings. The International Institute for Conservation was established in 1950 to “coordinate and improve the knowledge, methods, and working standards needed to protect and preserve precious materials of all kinds,” and in 1952 it began publishing Studies in Conservation to carry original scientific and practical papers (Gettens 1969, 12). Its first cumulative index, in 1967, listed 90 articles concerned with paint and paintings, or 56% of the total. Forty percent of the articles in the publication of the IIC Rome conference in 1961 concerned paintings (Thomson 1963). Two subgroups of the International Council of Museums combined in 1967 to form the new ICOM International Committee for Conservation, which publishes a triennial series of papers from its 26 working groups. Specialists in the conservation of furniture or textiles have essentially one key working group session to attend, whereas specialists in the conservation of paintings can attend nine different working group sessions, including “Structural Treatment of Canvas Paintings,” “Easel Paintings on Rigid Supports,” “Murals,” “Icons,” “Resins and Coatings,” and “Contemporary Art.”
Percentage of paintings conservation articles compared to the total number of articles on any conservation subject in key 20th century professional publications
The first cumulative index of the Journal of the American Institute for Conservation, 1977–1989 lists only 37 articles on paintings conservation of a total of 122 articles, or 30% of its contents. Considering that there are eight specialty groups in the AIC, this is still perhaps an unfair share. However, members of the other specialty groups may be pleased to note that as new art history methods are revising many of the hierarchies of the canons of art history—including the amateur status of women artists—the supremacy of paintings conservation is also under measurable revision.
Perhaps the two most controversial and potentially irreversible things paintings conservators do is to clean and to line paintings. Many changes have taken place in these two pursuits in the last three decades, since the 1960s. The 1960s were noted for worldwide turmoil, but the 1970s witnessed the greatest number of changes in conservation. This paper attempts to assess how much published research has affected these changes. “Research” is defined in Webster's New World Dictionary as “careful, systematic, patient study and investigation in some field of knowledge, undertaken to establish facts or principles.” If we look again at these same signpost publications, we can see a shift from articles reporting “this is how I treated this painting” to “careful, systematic ‘investigations’ to establish facts or principles” (fig. 2). The percentage of research articles has steadily increased from 0% to slightly more than 50%, but many of these articles are about pigments used by certain artists or results of instrumental analysis, which produced findings that may not actually have an impact where the swab meets the varnish or the canvas meets the adhesive.
Percentage of articles about paintings conservation research compared to the total number of articles on paintings conservation in general in key 20th-century publications
To assess the practical impact of conservation research on the treatment of paintings, a list of researchers was drawn up based on the following criteria: (1) their research was published; (2) the research had appeared in English-language publications within the last three decades; (3) the research related to practical aspects of cleaning or lining paintings. A draft list and a questionnaire were circulated to four paintings conservation colleagues, asking for corrections or additions. Their responses produced this list:
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.
6 AWARENESS OF WHAT IS YET TO BE SOLVED
R. J. Gettens and G. L. Stout kept updated lists of areas in need of further investigation during the early days of the Fogg (Fogg Art Museum 1930). This precedent was continued with lists compiled by the National Institute for the Conservation of Cultural Property (1984) and a report of an AIC membership survey compiled by Eric Hansen and Chandra Reedy for the AIC Task Force on Conservation Science (Hansen and Reedy 1994).
Some survey respondents noted that research is sometimes unrelated to actual treatment situations or relies on unaffordable equipment. Nathan Stolow commented in his FAIC oral history interview that the Canadian Conservation Institute was designed with windows in the scientific laboratories that obliged the scientists to look down into the treatment areas where the actual work had to be carried out (Stolow 1976).
About a dozen respondents noted that our field often comes across as hostile to new ideas. However, the current principles of minimal intervention can be traced back not only to the hope of Pettenkoffer but also the 1940 Manual on the Conservation of Paintings(International Museums Office 1940). From the section on lining:
There are however, cases of well-preserved canvas paintings, several centuries old, which do not yet need relining…. Many curators maintain that paintings should be interfered with as little as possible (212).
And from the section on cleaning:
It is often suggested that, in cases where it is necessary to disturb the varnish, only the upper portion of it should be removed, leaving the remainder before getting dangerously near the original paint (124).
Max Planck noted in Scientific Autobiography (1949, 33–34): “A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.” All of our “current” points of view are of course subject to what future conservators choose to make of them. Perhaps one of the best things we can do for each other and our students in the time we have is to point calmly to the doors we need to open to learn more about what we do not yet know.
The author would like to thank Chandra L. Reedy for preparing the statistics and also the conservators who returned surveys.
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JOYCE HILL STONER is the director and chair of art conservation for the University of Delaware/ Winterthur Museum, for which she has taught for 18 years. She is a graduate of the New York University Conservation Center and has been a visiting scholar in paintings conservation at the Metropolitan Museum of Art and the Getty Museum. From 1969 to 1986 she served as managing editor of Art and Archaeology Technical Abstracts and has coordinated the FAIC Oral History Archive since 1975. She was senior consultant for the team treating J. M. Whistler's Peacock Room, Freer Gallery of Art, from 1988 to 1992 and is currently writing a doctoral dissertation on facture, technique, and friendship in the works of Whistler. Address: Art Conservation Dept., University of Delaware, 303 Old College, Newark, Del. 19716.
This paper was presented in the Conservation Science update session at the 21st annual meeting of the American Institute for Conservation of Historic and Artistic Works, June 1993, Denver, Colorado.