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Clean Art?

Charles S. Rhyne
Reed College

Journal of the American Institute for Conservation
Vol. 45, Fall / Winter 2006, pp. 165-170.



Originally presented as the introduction to a session on the cleaning of art at the 2004 annual meeting of the American Institute for Conservation of Historic and Artistic Works, this paper is not limited to one type of art but attempts to consider issues relevant to all forms, materials, uses, and periods, from any region or culture. It encourages what might be called “comparative conservation.” The article focuses on the diverse purposes for which art is cleaned, and attempts to facilitate the ongoing discussion of the values embodied in these choices and the means to achieve them.

1.  Introduction

Should art be cleaned? This seemingly straightforward question is, of course, simplistic in the extreme. What art? How clean? For what purpose? Is the object deteriorating badly? Has its appearance been distorted? Can the desired change be achieved instead through lighting or display? Will cleaning uncover historical evidence of special importance? Is cleaning technically possible without damaging the object? If cleaned, can the object be stabilized? Are trained professionals and the necessary equipment available? The question of whether or not to clean any historic or artistic work is cut through by multiple considerations such as these overlapping in ways unique to each object.

     High profile cases appear on the front pages of newspapers around the world. This attention is providing much needed publicity for the field of conservation, involving the public in the types of expertise needed for the preservation of our cultural heritage. Regrettably, however, media reporting on these high profile cases has been formulated largely in terms of controversy, often leaving the public confused and significant achievements and discoveries overlooked.  In addition, some of the protagonists continue to misrepresent the results of individual cleanings. I have attended lectures in which the speaker has shown severely overexposed slides of details of the cleaned Sistine Chapel  ceiling and directed the audience to see how the conservators had cleaned away much of the form and flattened the figures. Such misrepresentations are so extreme and so obvious that they appear to be deliberate, and this is surely counterproductive. There are important issues to be raised about every cleaning, including that of the much-publicized Sistine Chapel Ceiling, but such misrepresentations make it difficult for the public, sometimes also conservators and scholars, to tell which ones to take seriously.

     Less dramatically, but with more far-reaching benefits, conservators, curators, art historians, archaeologists, anthropologists, and members of originating cultures have been engaged in thoughtful reexamination and debate. In professional conferences and publications, case studies involving cleaning are being shared and discussed.

     Outstanding publications are making these ideas available to other professionals and the public. Of special note is the small volume, Personal Viewpoints: Thoughts about Paintings Conservation, based on a 2001 seminar organized by the J. Paul Getty Museum, Getty Conservation Institute and Getty Research Institute (Personal Viewpoint 2003). Although limited to Euro-American paintings, it provides a remarkably open discussion of changes within the profession of art conservation and is a must-read for anyone studying the cleaning of any art. In the seminar, six distinguished conservators “agreed to reconsider one or two treatments that they had done in the past and reflect in public why they approached the work the way they did and what, if anything, they would do differently today” (p.vii). The result is a uniquely revealing series of case studies, in which alternative approaches are thoughtfully presented and discussed. Elsewhere also, Museums have mounted exhibitions focusing on the conservation of works in their collections. Others are cleaning works in view of the public, others posting web sites tracking the process as it unfolds.

2.  Distinctive Concerns of these Papers

This issue of the Journal is distinctive in several ways. Most publications that examine cleaning, discuss it as part of the overall conservation process, quite naturally, since all cleanings are dependent on other aspects of conservation and cannot be understood in isolation. Nevertheless, by focusing on cleaning, we are able to consider its unique role in the conservation process. The object, once cleaned, can never be restored to its previous condition.  Moreover, cleaning brings about one of the most obvious, sometimes dramatic, changes in the visual appearance of objects, and as such has a powerful effect on our response to and understanding of historical and artistic work.

     One of the points rarely made about the Sistine Chapel Ceiling is that much of the previous scholarly and critical literature on Michelangelo’s masterpiece was based on the assumption that the distorted condition in which it existed for many years revealed the artist’s aesthetic choices. Yet we have no photographs that show what these authors were writing about. Previous to the installation of the twentieth century floodlights, much of Michelangelo’s form and color was invisible behind the dirt and discolored varnish that covered the surface. Indeed, this is how the ceiling looked immediately previous to the recent cleaning during non-public hours when the floods were turned off, even on bright sunny days. All published photographs of the ceiling previous to its recent cleaning were taken under strong floodlights in order that the imagery could be seen. Most before and after photographs of the ceiling, even in generally responsible publications, are seriously misleading. Very few viewers seem to notice that such comparisons show “before” images taken by bright floodlights, side-by-side with “after” images of the same view taken by natural light or much reduced floods. For example, in the generally excellent National Geographic article, comparison of the before and after photographs provides internal evidence of the misleading comparison. The uncleaned portion of the fresco is lighter in the “before” photograph than the same uncleaned portion in the “after” photograph, showing that the “before” photograph was taken under brighter light. The same clerestory window in the two photographs, taken straight-on in both photographs, reflects intense flood lights in the “before” photograph, much more natural light in the “after” photograph. Had both photographs been taken under normal lighting conditions, the fresco before cleaning would be seen to be much darker and the imagery and form less legible than appears in this misleading comparison (Jeffrey 1989, 704). Because of the transforming effect of cleaning on our understanding of and reaction to works of art, it has become probably the most debated aspect of conservation.

     Second, this issue of the Journal is unusual in focusing on the subject of cleaning across the entire range of artistic and historic artifacts: all types of objects, all materials, uses, periods, and cultures. A rare predecessor was the international conference, Surface Cleaning – Materials and Methods, organized by the Verband der Restauratoren at the Museum Kunstpalast, Düsseldorf (Düsseldorf 2003). Although most of the papers were, as usual, largely technical, there were important exceptions: papers by Ernst van de Wetering on the perception of surfaces; by Christian Scheidemann on dirt in contemporary art; by Hans Portsteffen on many other aspects of dirt; by Tanja Roskar Reed on non-tangible issues in ethnographic objects; and by Stefan Brüggerhoff on the usefulness and lack of usefulness of scientific tests for conservation. 

     An important book that, like this issue of the Journal, encompasses different types of objects in various media is Chris Caple’s Conservation Skills: Judgement, Method and Decision Making (Caple 2000). It is exceptional in including a fifteen page chapter, “Cleaning,” that deals with the full range of art and historical artifacts. Eight-and-a-half of these pages deal with the cleaning of objects other than paintings, with instructive examples. The book is also an important predecessor for this issue of the Journal in that it deals extensively with not only how things are done technically but why. This is perhaps the only book to present the field of conservation so comprehensively, including notable attention to archaeological and objects conservation.

     Another impressively comprehensive book is Elizabeth Pye’s Caring for the Past: Issues in Conservation for Archaeology and Museums (Pye 2001). For various reasons, Pye finds the term “cleaning” unfortunate and instead titles her six-page section “Removing material.” Although this forms a rather small section of this 232 page book, it is, like the rest, highly informative. The book shares the orientation of this article in that the author has “attempted to look for common ground between different fields of conservation” (p.6).        

     Because the physical characteristics of works of art and historical artifacts are so diverse, most publications on cleaning specialize on specific types of objects and materials: outdoor sculpture, Chinese bronzes, Romanesque wall paintings, historic masonry buildings, ethnographic objects, contemporary art.  Perhaps because oil painting has been considered the center of the post-medieval western art history canon, and because subtle variations in their appearance affect the expression and meaning of paintings more dramatically than with most other media, the majority of publications on cleaning is devoted to the cleaning of paintings.

     Most papers and articles on cleaning deal with one or a small group of closely related objects. A few major books are devoted to the cleaning and conservation of individual works of special importance. An outstanding example is Verrocchio’s David Restored (Radke 2003). This exemplary volume presents historical research establishing that a number of patinations during the eighteenth and nineteenth centuries altered the appearance of the sculpture. The authors present the basis for the 2002 cleaning, and describe the dramatic change that resulted. “The precious gilding that decorates the figure, especially the hair . . . represents not only the abundance of ornamentation that was standard in Renaissance bronzes (which scholars had long presumed to exist beneath the countless patinations), but also confirms that the statue was originally meant to be placed indoors . . . .” (p.13). “Some details of the finishing, such as the engraving on the trim, were almost completely concealed” (p.98).

     A second example, the cleaning of two larger-than-life, 14th century wooden sculptures of the Virgin and Mary and Saint John in the Württembergidsches Landesmuseum, Germany, although not a high profile case, demonstrates how transforming the cleaning of a sculpture can be.  By removing much later overpaint, the well-preserved 14th century gilding and ornamentation were revealed with detailed evidence for the original creative process (Westhoff, 1981, 143-154).  

     Even though most articles in this issue of the Journal also focus on a few closely related objects, my hope is that the range of media and types will encourage what we might call “comparative conservation.” What can we learn from the diversity of cleaning problems across the full range of historic and artistic works? In what ways do the characteristics of different media and forms of art not only call for different technical procedures but also affect the relative importance of evidence, appearance, and long-term health? What can we learn by reconsidering of our own approaches in relation to those of specialists in other fields?

     Finally, this issue of the Journal emphasizes not only how objects have been cleaned but especially why. Most publications within the professional conservation world, quite understandably, continue to concentrate on technical research and cleaning procedures.  For example, the “Preprints of the Contributions to the Brussels Congress” on Cleaning, Retouching and Coatings (Mills 1990) consist largely of important technical and practical papers. Yet, there are notable exceptions: articles on the Rothko Chapel by Carol Mancusi-Ungaro and on German Expressionist paintings by Kenneth B. Kutz, both of which probe the artists’ intent. Clearly the almost unlimited range of materials out of which historic and artistic works have been made requires specialized knowledge of and experience with the material being cleaned. But many of the papers in this issue of the Journal show not only how these procedures are dependent on technical and historical expertise, but equally how they depend on decisions about what most to value about each object and why. For future generations to understand the works of art they will inherit from us, it is essential that we record these reasons in our treatment reports as thoroughly as the technical processes employed.

3. All Objects have Changed

All objects have changed over time, some slightly, some drastically, and they have changed in many different ways for different reasons.  Some changes have been natural, others accidental, but many have been purposeful, including iconoclasm, experimentation, and previous cleanings and restorations. Elsewhere, I have described the surprising range of types of changes in the work of a single artist (Rhyne 1990). The evidence is sobering. There is a field of study, sometimes called “technical art history,” which might be thought of more broadly as “the physical history of art,” in which cleaning holds a significant place.

     One of the most pervasive misunderstandings about works of art among the public is that they look more or less the way they did when created. Obvious damage is recognized, but the degree to which the paintings, sculpture, and other works in museums have been reworked by the trade, sometimes several times over the years, to make them more saleable, each time according to the taste of the time; and the degree to which they have then been cleaned and restored by museums, to accommodate new research findings and make them more displayable are dimly understood. Even art historians are often uninformed about the physical histories of the objects about which they are writing. The extent to which the overall effect and meaning of paintings has been transformed by the severe darkening of some pigments in relation to others, altering relationships and obscuring details, is regularly overlooked. Few museum visitors consider the possibility that the painting they are looking at may have been trimmed or even cut out of a larger composition or that a sculpture may have been pieced together, somewhat speculatively, from dismembered fragments. The fact that much ancient sculpture and architecture was painted is accepted intellectually, but difficult to imagine when looking at Egyptian or Greek temples. Even highly educated people, standing in front of the carefully carved sculptural details on Pre-Columbian architecture, often find it difficult to accept that these were regularly covered with stucco and brightly painted, now largely cleaned off by centuries of exposure to the elements.

     Over the years, there have been various attempts to reconstruct the original appearance of ancient and Pre-Columbian stone architecture and sculpture, nearly all of which have lost their original surfaces. For these, rare paint remains surviving in protected areas have provided necessary evidence. Where supervised by leading scholars, these reconstructions have provided striking revelations of the colorful surface of much historic art, removed from the original objects by exposure to weather and invasive vegetation out of doors or which is otherwise invisible. Such reconstructions, even though partly speculative, are immensely informative and should be produced and made available far more frequently than is currently the case. A highly successful, recent example is the reconstruction of the so-called “Rosalila” temple at Copán, a full-scale clay replica, the elaborate façade decorations fully polychromed, on display in Copán’s recently opened sculpture museum (Fash and Fash 1996).

4.  Changes in the Professional World of Conservation

Equally important for understanding the cleaning of historical and artistic works are the considerable changes that have taken place within the professional world of conservation.  Apart from the increased emphasis on preventive conservation, significant advances in technical analysis and treatment, the explosion of digital imagery, and other procedures discussed in these papers, there has been a transformation in conservators’ areas of expertise and responsibility. It is now widely recognized, though not always practiced, that no cleaning of important art or historical artifacts should proceed without thorough scientific and historical research; and that decisions regarding reasons for each cleaning, methods to be used, and evidence to be recorded should always result from cooperative study by scientists, curators, art historians, living members of originating cultures, and where possible the artist. Moreover, it is recognized that conservators should be deeply involved at every stage in all of these areas.

     Publications co-authored by conservators and art historians are beginning to appear. In reading the landmark publication Seeing Through Paintings: Physical Examination in Art Historical Studies, by Andrea Kirsh and Rustin S. Levenson, one feels that the art historian and the conservator were involved in every sentence (Kirsh and Levenson 2000). Because the book’s organization follows the physical structure of paintings, there is no separate discussion of cleaning. In addition to cooperatively authored works, papers and publications by conservators themselves now take a more holistic view of their subjects. Some recent publications by conservators would previously have been authored only by art historians. The Getty Conservation Institute’s magnificent anthology, Issues in the Conservation of Paintings, which includes writings as early as the late fifteenth century, not only by conservators, but also by artists, curators, museum directors, and art historians, was edited by two distinguished conservators, David Bomford and Mark Leonard (Issues 2004). Part V is titled “Philosophical and Practical Approaches to Cleaning and Restoration,” and Part VI is devoted entirely to “Cleaning Controversies.”  

5. Alternative Values, Alternative Choices

Cleaning decisions require choices among alternatives, some of which impinge on others, some of which are even mutually exclusive. Increasingly it is recognized that all decisions regarding cleaning should be based on a clear understanding of the purpose of the cleaning, and that this should be explained and recorded in detail. Above all, it is essential that we recognize the diversity and range of these purposes. In extreme cases, all handling of the object by conservators may be avoided to agree with indigenous practice. In other cases cleaning may be rejected in order that the object may retain as much evidence of its past as possible. This evidence may include marks of making and use, natural deterioration, darkening and discoloring of varnish, the accumulation of ceremonial oils, previous re-paintings and restoration, and much else including previous cleanings. Cleanings of art often attempt to approximate as closely as possible the original appearance of the object, almost inevitably requiring restoration in addition to cleaning. Because the original appearance is to some extent unknown and, in any case, impossible to achieve completely, emphasis may be placed instead on aesthetic coherency, in which case the object may be cleaned selectively. In some cases, the object may be valued for its appearance at some other important stage in its history, which the cleaning can partly re-establish. In other cases, objects may be cleaned in order to achieve an impressive display or for publication. Or the cleaning may aim to bring the object into keeping with other closely related objects, to be displayed side-by-side. In other cases the main purpose of the cleaning may be to clarify the subject matter represented or to uncover important evidence. In most cases, cleanings aim to remove any damaging substances which threaten the long-term health of the object.      

     In a book published earlier this year, Contemporary Theory of Conservation, Salvador Muñoz Viñas discusses many of the complexities of conservation theory (Muñoz Viñas2005). In nine progressive chapters, the author makes an argument for the rejection of what he calls “classical theories of conservation,” based on “truth, objectivity and scientific conservation,” in favor of what he calls “contemporary conservation ethics.” Along the way he provides stimulating descriptions of many aspects of conservation theory, with examples and quotes from other authors. Most importantly, he stressed the importance of what he terms “value-led conservation.” Although aspects of the book are unconvincing, it challenges us to rethink our prior assumptions and deserves careful review.         

     Depending on the purpose of the cleaning, a given object may be treated in different ways. A portrait painting might be cleaned differently in an art museum, where the aesthetic coherency and hand of the artist would be most valued, than at a portrait gallery, where the image of the person represented might be preferred. In two articles on the conservation of totem poles, I have tried to describe the spectrum of approaches to the treatment of indigenous objects of a single type (Rhyne 2000 & 2003). Astonishingly, these approaches range from deliberate avoidance of any intervention to meticulous cleaning twice each year.

     Cleaning decisions attempt to maximize what is most valued about an object; and like most values, these vary from culture to culture, region to region, institution to institution, and from person to person. The most dangerous mistake would be to think that there is one correct solution for the cleaning of any object. Only the most basic human values have universal authority. It is the values embedded in the purposes for which objects are cleaned that most control cleaning decisions. What matters is that every cleaning of important art or historical artifacts be thoroughly researched and debated by all relevant parties, and that the treatment chosen be consistent with the particular complex of values decided upon. This issue of the Journal hopes to facilitate this ongoing discussion of values and the means to achieve them.  


Bomford, E.., and M. Leonard, eds. 2004. Issues in the Conservation of Paintings. Los Angeles: Getty Conservation Institute.

Caple, C. 2000. Conservation Skills: Judgement, Method and Decision Making. London: Routledge, Taylor & Francis. I have reviewed Caple’s book in Conservation and Management of Archaeological Sites 5(3), 2002, 185-187.

Fash, B. W. and W. L. Fash. 1996. “Saving the Maya Past for the Future: Copán’s New Sculpture Museum.” (accessed 6 Dec. 2005).

Jeffrey, D. 1989. "A Renaissance for Michelangelo". National Geographic 176 (6): 688-713.

Kirsh, A. and R. S. Levenson. 2000. Seeing Through Paintings: Physical Examination in Art Historical Studies. New Haven: Yale University Press.

Leonard, M., ed. Personal Viewpoints: Thoughts about Paintings Conservation. 2003. Los Angeles: Getty Conservation Institute.

Mills, J.S. and P. Smith, ed. 1990. Cleaning, Retouching and Coatings: Technology and Practice for Easel Paintings and Polychrome Sculpture: Preprints of the Contributions to the Brussels Congress, 3 – 7 September 1990. London: International Institute for Conservation of Historic and Artists Works.

Muñoz Viñas, S. 2005. Contemporary Theory of Conservation. Amsterdam: Elsevier, Butterworth, Heinemann.

Pye, E. 2001. Caring for the Past: Issues in Conservation for Archaeology and Museums London: James & James.

Radke, G.H. 2003.  D.A. Brown, M.L. Nicolai, J.T. Paoletti, B.P. Strozzi, S. Porcinai, S. Siano, and M.G. Vaccari. Verrocchio’s David Restored: A Renaissance Bronze from the National Museum of the Bargello, Florence. 2003. Atlanta: High Museum of Art, and  Giunti Grupo Editoriale, Florence.

Rhyne, C. S. 1990.  "Changes in the Appearance of Paintings by John Constable". 1990. Appearance, Opinion, Change: Evaluating the Look of Paintings: Papers given at a conference held jointly by the United Kingdom Institute for Conservation and the Association of Art Historians, June 1990.  London: United Kingdom Institute for Conservation, 72-84.

Rhyne, C. S. 2000. "Changing Approaches to the Conservation of Northwest Coast Totem Poles". Tradition and Innovation: Advances in Conservation. Contributions to the Melbourne Congress, 10-14 October 2000. London: International Institute for Conservation of Historic and Artistic Works, 155-160, color plates 7.1-7.4.

Rhyne, C. S. 2003. "Recent Approaches to the Conservation of Northwest Totem Poles". Zeitschrift für Kunsttechnologie und Konservierung 17 (1), 179-184. Paper presented at the 13th International Congress of the History of Art, London, Sept. 3-8, 2000.

Rhyne, C. S. 2002. "Review of Chris Caple, Conservation Skills: Judgement, Method and Decision Making". Conservation and Management of Archaeological Sites 5(3), 185-187.

Stoner,  J. H 19. 2002. “The Debate over Cleaning Paintings: How Much is Too Much.” IFAR Journal: International Foundation for Art Research 5 (3) 46-58.

Verband der Restauratoren. 2003. Surface Cleaning – Materials and Methods. An international conference held at the Museum Kunstpalast, Düsseldorf, Sept. 29-Oct. 4, 2003. The papers were not published, but abstracts were distributed at the conference. I thank Andrea Chevalier (Senior Paintings Conservator, Intermuseum Conservation Association, Cleveland) for providing me with copies and advice.

Westhoff, H. W. 1981. “Die Wiederentdeckung der Originalfassung zweier Skulpturen des 14. Jahrhunderts.”  Maltechnik /Restauro 87(3), 143-154.


Charles Rhyne is an art historian, Professor Emeritus, Reed College, Portland, Oregon. He has been a Fulbright Research Fellow at the Courtauld Institute, London; a Visiting Fellow at the Yale Center for British Art; a Kress Senior Fellow at the Center for Advanced Study in the Visual Arts, National Gallery of Art; and a Visiting Scholar at the Getty Conservation Institute, Getty Research Institute, and J. Paul Getty Museum. In addition to the history and theory of conservation, his areas of expertise include John Constable, images as evidence, and the use of digital images for research. A list of recent publications is available on his web site Address: Reed College, 3203 SE Woodstock Blvd., Portland, OR 97202-8199

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