JAIC 1998, Volume 37, Number 2, Article 2 (pp. 173 to 186)
JAIC online
Journal of the American Institute for Conservation
JAIC 1998, Volume 37, Number 2, Article 2 (pp. 173 to 186)



ABSTRACT—The Cleveland Museum of Art's The Thinker has a unique history in relation to the other original casts supervised by Rodin. In 1970, the museum's Thinker was blown up by radical protesters. This article will explore some of the complex ethical and practical issues surrounding its treatment. Of equal interest is the history of protective coatings that have been used on the sculpture. The records available at the Cleveland Museum of Art show early concern over changes in The Thinker's patina by the museum's first director, who sought advice on its care. In the past, wax and two commercial oil preparations were applied as protective coatings. Currently The Thinker has been stabilized with an Incralac coating and is washed and waxed twice a year.

TITRE—Vingt-cinq ans après la bombe: l'entretien du Penseur de Cleveland. RÉSUMÉ—Le Penseur du Cleveland Museum of Art possède une histoire unique par rapport aux autres moulages originaux créés par Rodin. En 1970, un groupe de manifestants radicaux fit exploser la statue. Cet article examine quelques-uns des aspects déontologiques et pratiques complexes qui survinrent pendant la restauration du Penseur. Un aspect intéressant du travail fut la mise á jour de l'histoire des couches protectrices qui furent appliquées sur la statue. Des archives du Cleveland Museum of Art montrent que le premier directeur du musée s'inquiéta du changement survenu dans la patine du Penseur et chercha conseil pour sa préservation. Dans le passé, de la cire et deux préparations commerciales á base d'huile furent appliquées comme couches protectrices. Actuellement, Le Penseur a été stabilisé avec une couche d'Incralac; il est lavé et ciré deux fois par an.

TITULO—Veinticinco años después de la bomba: el mantenimiento de “El Pensador”. RESUMEN—La estatua de “El Pensador” del Museo de Arte de Cleveland, cuya fundición fue supervisada por Rodin, comparada con otras, también supervisadas por Rodin, tiene una historia singular. En 1970 una bomba puesta por elementos radicales la hizo explotar. Este artículo se dedica a explorar algunos de los complejos asuntos éticos y prácticos relacionados con el tratamiento de conservación de la escultura. De igual interés es la historia de las capas protectoras que se han usado sobre la escultura. Los documentos en los archivos del Museo de Arte de Cleveland demuestran la preocupación temprana del primer director del Museo en cuanto a los cambios observados en la pátina de “El Pensador”, quien solicitó consejo sobre el cuidado de la escultura. En el pasado, capas de cera y dos preparaciones comerciales en base de aceite fueron aplicados como agentes protectores. Actualmente, “El Pensador” ha sido estabilizado con una capa de Incralac y se lava y se encera la obra dos veces al año.


The history of The Thinker at the Cleveland Museum of Art is unique in relation to the other original casts supervised by Auguste Rodin (1840–1917) (see appendix). Shortly after the sculpture was acquired in 1917, the director of the museum sought advice about its maintenance outdoors from Frank Purdy of the Gorham Company. Purdy, a prominent expert, also gave advice to other museums and collectors during the early years of this century, so it is likely that many outdoor bronzes in this country received similar treatment. Then, in 1970, Cleveland's Thinker was blown up by radical protesters, one of the last acts of civil unrest that marked the turbulent 1960s.

The museum's records on The Thinker are of interest to conservators not only as they document early conservation practices for outdoor bronzes but also as they explore complex ethical and practical issues surrounding the treatment of damaged art.


Records about the care of The Thinker come from three sources—the museum's archives, the curatorial records, and Conservation Department records. As might be expected, over a halfcentury these records are uneven and often sketchy. In the early years, day-to-day records and correspondence document the treatment the sculpture received during the administration of Frederick Whiting, the museum's first director (May 1913–August 1930). Records of treatment stop in 1925. The museum's Conservation Department was established in 1958, and before that date conservation work was undertaken by a number of outside conservators, notably William Suhr and Rostislav and S. N. (Nicky) Hlopoff. Information presented here also comes from personal communications with the late Frederick Hollendonner, former chief conservator, and with Superintendent Victor Kavosic, Cleveland Police Department, and from direct observation of coating procedures carried out at the museum.

The Cleveland Museum of Art acquired The Thinker in 1917 (1917.42), one year after the museum opened its doors, as a donation from Ralph King. First displayed inside in the rotunda (fig. 1), within several months the sculpture had been moved outside to the south entrance of the museum (fig. 2). In a letter dated February 2, 1918, to Miss Anna Seaton-Schmidt, a pupil and friend of Rodin, Whiting explained this move.

Fig. 1. 1917 photograph of The Thinker still inside the Cleveland Museum of Art with an intact patina

Fig. 2. 1930 photograph of the The Thinker outside the south entrance of the museum

Your article in the February American Magazine of Art on Rodin reminds me of your intimate association with him, and prompts me to write to ask your opinion regarding a matter which has been much in my mind of late. You perhaps do not know that we have had given to us a full size bronze replica, purchased before Rodin's death and through him, of the “Thinker.” This was originally placed in the Rotunda of the Museum, which is not strongly lighted, but with the consciousness on my part that this was not the condition of lighting for which the figure was planned by Rodin. After showing it in this position for several months I removed it to the platform in front of the Museum which in a way approximates its position in Paris in front of the Pantheon. Miss Malvina Hoffman had urged me to do this when she saw it in the Rotunda, where she thought it was not properly lighted. I have recently learned, to my regret, that the donor is very much disappointed that it had been placed out of doors instead of being kept in the Rotunda. If you agree with me as to what Rodin's wishes would be in the matter I feel that a letter from you expressing your pleasure that the figure has been properly placed in front of the building in full daylight would aid me in convincing the donor that I am right. Of course, such a letter could be in answer to my inquiry as to the better place for the figure and not refer to my cause for making such inquiry.

Anna Seaton-Schmidt replied on February 7, 1918, expressing her delight that the museum had been fortunate enough to acquire The Thinker. As to the sculpture being placed outdoors, she wrote:

Oh I so hope that you can place it as originally intended, up high, and in a strong light, or a rather diffused light, so that the strength of the figure may be revealed and no small details accentuated. I presume an out door position might be best, as, of course, it was intended to crown his great doorway “La Porte d'Enfer”— (designed for the Palace of Decorative Arts, never completed) …. But I don't know that he desired it seen in a certain way—no one ever paid more attention to the proper light in which his figures were seen, because it is so very important for sculpture.

She emphasized in another paragraph: “Above all it must be high. Even the one in front of the Pantheon is not high enough, but that could not be helped.”

Once the sculpture was outside, Whiting noticed problems with the patina almost immediately. Two letters provide insight regarding the appearance of the original patina. In a letter dated October 9, 1917, to Malvina Hoffman, another student and friend of Rodin, Whiting wrote:

I am taking this opportunity to ask your advice about the large Rodin “Thinker” which you saw when it was installed in the Rotunda of the Museum and which since, in accordance with the suggestion which I made to you and of which I was glad to have your approval, I have moved out onto the plaza in front of the building. You will remember that it had a rather lovely blue patina on it while it was inside, and this has entirely washed off in the outside weather so that the figure is now very dirty looking and of no uniform color, there being some few little patches of blue left, some brown, and others a rather raw brass color.

Whiting went on to ask what Rodin would have wanted under the circumstances. Unfortunately, Malvina Hoffman's reply does not exist in the archives.

The color of The Thinker is again mentioned in a letter to Purdy of the Gorham Company, dated October 22, 1917. “The large bronze replica of ‘The Thinker’ by Rodin which Mr. King got for us we have placed outside in front of the building where it is very gradually changing color. The bluish patina has almost entirely washed off, the statue now being extremely streaked.” Purdy apparently had close ties to Rodin. A letter from Purdy to Whiting, dated July 28, 1915, asks if the Cleveland Museum would be “interested in obtaining any of the original works of Auguste Rodin. I have favorable indication of being able to secure some of his work from the Master himself, in fact, am at present negotiating with him for a full size copy of his ‘Age of Bronze.’ I should esteem an expression of opinion from you in this regard in strictest confidence.”

Purdy would become a key player, advising the museum on care for the sculpture. Letters between him and Whiting, from 1917 to 1921, are the earliest records regarding the care of the sculpture. On October 24, 1917, Purdy recommended:

With reference to the bronze of “The Thinker,” it ought to be possible to rub this down by hand in such a way that the patina would come together. Bronzes which are out of doors should be treated in this way about once a year. After that they should have a beautiful skin that would require treatment every two years. Just before the outbreak of the War, Colonel Harts of the White House and the Bureau of Weights in Washington and myself were collaborating with the idea of treating all of our Public Monuments in this way, so they would ripen with time, rather than to get looking like old iron.

Whiting's reply, on November 2, sheds some light on this hand rubbing method:

[A]nd we will try the flannel and hand method in treating the bronze “Thinker.” I am sure that I told you before that the figure is now out of doors and the thing I hoped to find was how I could remove some of the spotted effect which has come about by the washing off of the bluish patina which Rodin put on it and which was apparently not thoroughly grounded into the bronze. I presume from what you say that this will come off gradually with the hand rubbing and I will see that a man is delegated to give a frequent treatment of this sort.

On October 31, Purdy instructed:

I should strongly depreciate the using of ammonia water, no matter how thoroughly diluted, unless handled by an expert, for the reason that if the ammonia starts to eat into the bronze, there is no known way of stopping it.

If it should transpire that the particular Bronze you have has any porous spots, which is more than likely to be the case, the ammonia might eat straight through, unless administered by a practiced hand.

As I stated at the Metropolitan Museum Meeting in the Spring, there is nothing on earth so good for any Bronze as the human hand. If I had the same condition as you have, I should provide a man with several pieces of clean soft Canton flannel, and rub the bronze frequently, using the soft side thereof, all over, and if you should induce your man or men to use the palm of their hands—first a rub of the flannel, then of the hand, an enamel finish should be produced that would be beautiful and lasting.

Of course I could provide you at any time with an expert to repatinate the figure completely, but I believe that this hand and cloth rubbing will give you a beautiful result.

I should depreciate the use of any solutions whatever. The method I describe is simple, not costly, and absolutely safe.

By June 1920, Purdy had changed his thinking on the care of outdoor bronze sculptures and advised the museum to apply wax to The Thinker. On June 10, Whiting described the new stone pedestal for The Thinker as already somewhat discolored by the bronze figure and asked if the wax would stop the staining of the stone base. He also complained that the figure looked dull. Could the wax be buffed? In Purdy's reply, dated June 24, Purdy asserted: “The wax coat should prevent further discoloration absolutely of the bronze, and should not contribute in any way to the discoloration of the pedestal.” He went on to say that if desired the wax could be carefully rubbed with a soft cloth. In a December 21 letter to Purdy, Whiting wrote:

I think that you will be interested to learn that, since receiving the preparation which you sent to us to put on the bronze “Thinker” which is at the front of the building, we have made two applications one in the summer and one in the early fall using up for this purpose all of the preparation which was sent us. Despite these two treatments we do not seem to have entirely arrested the discoloration from the bronze and the artificial stone pedestal on which it stands is becoming more and more discolored as time goes on. Have you any further suggestion to make as to these treatments?

By April 1921, Whiting asked if Purdy would be in Cleveland in the near future “as there seems to be a constant running of the color, despite the treatments with the wax preparation, and the artificial stone base is fast becoming a greenish color from this cause. We do not object to the discoloration of the base, but it seems to indicate a deterioration of the bronze, which may be disastrous in time, if allowed to continue.” In 1921, Whiting inquired about purchasing more wax from Gorham Company and was reassured by Purdy that applying another coat of wax would cause no harm.

After 1925, there are no records on the routine care of The Thinker in either the archives or the curatorial files. It is not clear why the records suddenly stop at this point. Frederick Whiting remained as director until August 1930 and it is unlikely that problems with The Thinker stopped suddenly or that Whiting's concern was any less. Perhaps Purdy retired from Gorham Company, or more likely the written correspondence was replaced by the telephone. In any case, at some later date the art handlers were sent outside with Gorham Company's AB Mixture—a petroleum-based product—and instructed to coat the sculpture with this material.1 This treatment was certainly being carried out from the 1950s onward. The museum's second director, William Milliken (August 1930–March 1958), may have started this practice, perhaps advised by the Gorham Company, which was marketing a new product. It is not clear how often the oil was applied to the sculpture. By the late 1970s the application of the AB Mixture was somewhat sporadic. The product applied to the sculptures was also changed at this point because AB Mixture was no longer available. Birchwood-Casey's Sheath Rust Preventive was used and is a similar, although more sophisticated, product containing corrosion inhibitiors.2

The results of these past treatments ranged from little to moderate protection for The Thinker. The earliest treatment recommended by Purdy—rubbing the sculpture with the hands and a cloth–seems to have been more aesthetic than truly protective. Purdy did not elaborate on how this rubbing treatment would stop corrosion. It seems that several things—both aesthetic and protective—may have happened with this treatment. The rubbing of the bronze surface may have removed dirt and pollutants as well as any residual patination chemicals not carefully washed from the bronze. The oil from the hands would help saturate the surface, thus making it appear more visually integrated. Oil from the hands may also have imparted some protection from water. However, this treatment would also have introduced salts and acids that, over the long run, could not have been beneficial. One can only speculate that Purdy had observed areas of bronze sculptures that had developed a lustrous patina from constant handling and formed the opinion that rubbing with the hands was good for the bronze.

The composition of Purdy's wax was not given, but it must have provided more protection from the elements than the hand and cloth rubbing. He recommended that it be applied twice a year but did not recommend heating the wax or the sculpture. The protection given by the oil preparations appears to be moderately successful but uneven. The upper surfaces are the most exposed to both the sun and rain, resulting in a loss of oil from these surfaces and their subsequent corrosion. When The Thinker was coated with Incralac, the oil was found to be still in place in the lower and better protected areas but was absent in the upper surfaces. The sun may have volatilized the oil in the upper areas, and the rain also helped to remove the oil by washing it down the sculpture. In general the upper surfaces of The Thinker were most heavily corroded, with some erosion of the metal and much loss of the original patina. The lower and better protected areas had little or no corrosion, retaining the remaining original patina.

It is evident that as long as the oil stayed in place, it did provide a modest amount of protection for the bronze. Unfortunately the various protective coatings do not seem to have been applied in a routine and systematic way. So, the protection of The Thinker from weathering has been uneven. It is clear that The Thinker would have been better preserved if it had been attended to on a more regular schedule.

Purdy's influence on the treatment of outdoor bronze sculptures should not be underestimated. From the references in the correspondence, he was obviously concerned about preservation and was influential at several levels. He described his methods at a Metropolitan Museum of Art conference in the spring of 1917. While little is known about this meeting, it seems likely that representatives from many of the major museums in this country attended. Purdy was also involved in a project with Colonel Harts of the Bureau of Weights and Measures to preserve public monuments. At this time they were promoting the hand-rubbing method. Purdy also seems to have been speaking to artists, specifically to Auguste Rodin. It is not known if he expressed his views on preservation to Rodin, but he had close ties to the sculptor as he essentially acted as a dealer for him.


In the early morning hours of March 24, 1970, dynamite was placed between the legs of The Thinker. The results were devastating (fig. 3). The base and the lower part of the legs were annihilated, and the remaining sculpture was knocked off of its pedestal. The Thinker lay face down, apparently contemplating Hell much more directly. The blast sent pieces of bronze flying, causing damage to the building approximately 20 yards away. The bronze doors of the museum were dented, and the marble columns were chipped. This damage can be seen to this day. Pieces of bronze were even found on the roof. According to the Cleveland Police Department, this act of terrorism was conducted by a radical Weatherman group operating in Cleveland. Members of the group later moved to New York City, where they were killed making explosives.

Fig. 3. 1970 photograph of The Thinker after the bombing

The sculpture sustained considerable trauma. The obvious damages mentioned above were the loss of the feet and lower areas of the legs. The seat supporting the figure was severely distorted. The sculpture also sustained damage not so easily seen. The explosion caused much of the lower half of the sculpture to expand and to be twisted and contorted in areas. In addition, there was some abrasion and scraping of the metal where the head and shoulders hit the pavement.

A number of treatment options were examined and contemplated by Edward Henning, curator of modern art; Frederick Hollendonner, objects conservator; and Sherman Lee, third director of the museum (April 1958-June 1983). Noted experts, both art historians and conservators, were consulted on the issues surrounding The Thinker. Again, the archives and the curatorial files contain a wealth of information. A number of opinions were expressed, ranging from mounting the object as it was to obtaining a new cast from the Rodin Museum. One of the more knowledgeable and reasoned letters came from Professor Albert Elsen, Stanford University, to Sherman Lee, dated June 18, 1971:

You ask me what, as a Rodin scholar of over 20 years, I think Rodin's position would have been in this circumstance. In his lifetime he himself would have either repaired the work or supervised a new cast. I must say that it is possible he might have consented to restoration by someone else whose work he approved of. But I think the strongest case can be made for your position. As you know, Rodin was the first sculptor in history to take seriously the partial figure as a complete work of art and to accept, court and even welcome chance and accident in the making or subsequent history of his sculptures. I have written about this in my book on the partial figure. While he himself mutilated plaster enlargements, (and the Thinker was an enlargement), it was for the purpose of editing the work of his assistants. He did accept studio accidents that resulted in the battering, breaking and discoloring of works over a long period of time. (The Met has such a torso in plaster obtained directly from Rodin.) In 1900, Rodin actually exhibited a fragmented version of the Thinker and it can be seen in a photo on page 186 of the Descharnes and Chabrun book on Rodin. (The plaster lacks at least the head.) In Rodin's view, his sculptures were so well made, so beautifully formed and expressive throughout, that like classical fragments, parts of his work could hold up as being complete in themselves. Even in its present, ruined state, your Thinker is still an impressive sculpture and supports Rodin's view. Only Rodin's work by its history and the way it was made can withstand such a tragedy, with any degree of dignity.

Essentially, the museum studied three treatment options: (1) take molds from other original Thinkers and make a replacement cast; (2) make a cast from molds and cut the newly cast sculpture up to replace damaged areas of the Cleveland sculpture; or (3) mount the damaged sculpture and essentially do no restoration. Joseph Ternbach, a conservator in private practice specializing in metal conservation, acted as a consultant to help study the practicality of the options. Considering the extent of damage and the difficult ethical issues there was no obvious or perfect solution.

The making of a new cast after the death of an artist is always problematic. Casting sculptures in bronze is a technique that lends itself to accurate multiple reproductions. The original Thinker owned by the Cleveland Museum of Art was one of the few that had been cast and patinated under the supervision of Rodin. A number of other Thinkers were cast shortly after Rodin's death, and the Rodin Museum continues to make sculptures for sale. At what point does a recast become a reproduction? In Sherman Lee's opinion casting a new sculpture would lack the quality of either the original or even those cast shortly after Rodin's death. It was felt a recast in this situation would in essence be a reproduction.

Cutting and welding a new cast to the original were fraught with technical problems. The whole reproduction process of taking a new mold, making a wax model, and casting a new bronze sculpture generally results in significant shrinkage of 5–10%. Matching up parts with different proportions would result in parts that could not be fitted together. The model could have been enlarged by pointing up by some percentage, but predicting the exact percentage would be difficult. Also the pointing up of a larger model would introduce another step that would take the casting one step further from the original.

There was also significant distortion of the lower parts of the sculpture, because the explosion expanded the metal in some areas. Even if an exact match in size could be achieved the pieces would not have aligned well due to the changes in the sculpture's dimensions. The other option would have been to cut away the expanded areas of the sculpture in order to achieve a better fit, but significantly more of the original sculpture would be lost. Perhaps less than half of the sculpture would remain.

Even if all the technical problems were overcome and the new pieces were matched up to the original sculpture, other ethical issues developed. How far does one take the visual integration of the two parts? Should the new areas be patinated a slightly different color from the original so that viewers could differentiate the original sections from the made-up sections? Would Rodin have approved of the aesthetics of a two-toned sculpture?

The last option of mounting the sculpture in its damaged state also had significant ethical implications. This option would preserve what was left of the sculpture directly supervised by Rodin but sacrifice some of the artist's original intent. While Albert Elsen states that Rodin did accept happy accidents in the creative process and used partial sculptures to edit his students' works, there is no clear evidence that he would have been happy leaving the sculpture in its damaged state. It is interesting to reflect that ever since the British Museum mounted the Elgin Marbles as fragments in the 19th century, we have come to accept the concept of a fragment from a sculpture as being a complete work of art. For most classical sculptures we do not know what the original complete sculptures looked like, and doing any type of restoration would be both impossible and unethical. However, the original form of Cleveland's Thinker is well known. The mounting of the sculpture in its damaged state turns The Thinker from being purely an art object into a historical document. For better or worse, an antisocial statement had been made and has now become part of the history of this particular sculpture.

As the correspondence in the curatorial files and the archives show, these issues were explored with curators, museum directors, conservators, and artists. After discussing the implications of the three options, the third was selected for a number of reasons. First and foremost, this option preserved what was left of the original sculpture. The first option (making of a new cast) was rejected because it would be a replica and not a cast personally supervised by Rodin. The sculpture had become so distorted by the expansion of the metal during the explosion that the second option could not be seriously considered. Sherman Lee summed up the museum's final position in a letter to Professor Albert Elsen, dated June 15, 1971:

We wish to maintain the figure in its present damaged state as a historical document and in accordance with what we believe Rodin's thinking would have been on this problem. In any case, we do not wish the sculpture to be repaired since the extent of damage requires such extensive repair and replacement that we believe that it would be no better than a modern cast comparable to those issued by the Rodin Museum.

The sculpture was then mounted on a bronze armature and placed on a tall granite pedestal with the inscription “The Thinker / by Auguste Rodin / Gift of Ralph King / (and in smaller letters) Damaged 24th of March 1970.”

There was little emotional reaction from the press and public to the museum's decision to place the damaged sculpture on view outside the museum (fig. 4). Nearly all of the newspaper articles repeated the events of the bombing matter-of-factly and reported the museum's decision to place the damaged sculpture on view, citing the museum's reasoning. Interestingly most of the real reaction dealt with the incomprehensible and irrational act of the bombing itself. There was much concern about public safety.

Fig. 4. 1974 photograph of The Thinker as it was remounted after the bombing


In 1980, the museum began a program to maintain all of its outdoor sculptures—including The Thinker—on a more regular basis (fig. 5). The previous treatments of oil had left a fairly thick film, which had trapped a great deal of dirt, in the protected and lower areas of The Thinker. In order for any treatment to be successful, it was imperative to remove the oil.

Fig. 5. 1974 photograph of The Thinker, three-quarters view showing the corrosion pattern

The Thinker was first washed with Orvus anionic detergent and water. This successfully removed much of the dirt but not much of the oil. Acetone and cotton swabs were used to remove the oil. The application of acetone was repeated several times until there was no evidence of oil coming up in the cotton. Two thin brush coats of Incralac were applied followed by two spray coats. The Thinker was then given a final layer of wax.

The Thinker now receives routine maintenance twice a year, in the spring and fall. It is washed with Orvus soap and rewaxed with either MinWax or Butcher's Bowling Alley Paste Wax. Any breaks in the lacquer are touched up. At the time The Thinker was treated with Incralac many conservators were using this product as a protective layer. It was felt that the acrylic coating would provide better protection for the sculpture in an outdoor environment. To date, the Incralac coating on The Thinker has not degraded enough to require its removal from the surface. Based on experience with several of the other sculptures in the museum collection, the removal of the Incralac is a slow process. Because of this difficulty in removal, the continued use of Incralac on The Thinker will need further study.

More extensive treatment, such as aesthetic reintegration of the patina on The Thinker, was not done as the sculpture has been so radically altered by the bombing. So much of Rodin's artistic intent was altered by the bombing that the corroded surface is a relatively minor issue. This sculpture has taken on a life of its own–part Thinker by Rodin, part history, part social statement. A unique and haunting beauty has emerged. The museum's philosophy is to stabilize the sculpture in its present condition.

Recent detailed examination of The Thinker indicates that there may be additional damage from the explosion. Deep pits are present on the legs and other lower surfaces. These pits are located within “sight line” of where the dynamite was positioned. They have ragged edges and seem to erupt from the surface, suggesting they may have been formed from the percussion of the explosion. Essentially, the pits are incipient tears and cracks in the metal. At the center of many of the pits are areas of light green corrosion, which may be caused by chemical residues left from the dynamite as it is not seen on other areas of the sculpture. X-ray diffraction analysis of this corrosion indicates it is copper chloride hydroxide.3 With most high explosives, the presence of nitrates would be expected. These observations suggest, however, that a chlorate-based explosive may have been used. One explosive with a sodium or potassium chlorate-base goes under the name of Cheddite.4 Cleveland Police Department Forensic Laboratory records show that the explosive was never identified.

Another problem is the presence of wildlife inside the sculpture. Because the bottom of the sculpture is now open to the elements, birds found it is a great place to nest. The nests have now been pulled out, and nylon screening coated with tinted Incralac has been worked up inside of the legs and the figure to deter future inhabitation.


Over the years the Cleveland Museum of Art has tried to care for The Thinker using such measures as waxes and oils—often intermittently—to maintain the sculpture. The museum's current philosophy for its care is a conservative one. The sculpture has certainly changed—to say nothing of the surface—from the time that it left Rodin's studio. Much of Rodin's artistic intent has been significantly altered or lost. After the bombing, the museum staff made the decision to preserve what remained of The Thinker.

The current goal of the museum is to keep its condition stable. A more aggressive treatment can be undertaken in the future. Not to treat an object is a valid treatment option, but it is not without ramifications.

Much of the original artistic intent of the Cleveland Museum of Art's Thinker has been altered. What was once a sculpture has become a historical document. The museum has preserved what is left of Rodin's sculpture as well as something of America's social history in the late 1960s and early 1970s. In a letter to Sherman Lee, dated June 18, 1971, Professor Albert Elsen succinctly summed up the problem and the solution: “I know the temptation will be strong to show it as it is, which makes it above all a monument to an insane act.”


I would like to thank Diane O'Malia for her invaluable assistance in the archives of the Cleveland Museum of Art. Thanks is also extended to the Conservation Department for its encouragement and patience, especially to Patricia Griffin for her insights and constructive criticism and to Judith DeVere for her help in editing the manuscript.



Other bronze casts of the enlarged version of The Thinker are listed below, by location:


  • City of Buenos Aires, Plaza del Congresso.


  • Laeken. The cast is located in the cemetery near the royal palace.


  • Ny Carlsberg Glyptotek, Copenhagen. Purchased by Carl Jacobsen in 1906.


  • Musée Rodin, Paris. Gift to the city of Paris and originally installed in front of the Pantheon. Removed by order of the Ministry of Public Instruction to the Musée Rodin in 1922. 1906 cast by Hébrard.
  • Musée Rodin, Meudon. Over Rodin's tomb. Cast in 1916 by Alexis Rudier.


  • Kunsthalle Richard Kaselowsky-Haus, Bielefeld. Purchased in 1968. Cast by George Rudier and numbered 13/13. The Musée Rodin has the right to make only 12 posthumous bronze casts of each one of Rodin's plasters. In this case, the numbering is either a mistake or the sculpture is an illegal cast.
  • National-Galerie, Berlin (formerly in the Eastern Sector).


  • National Museum of Western Art, Tokyo. Ex-collection of Matsukata. Cast by Alexis Rudier.
  • Kyoto National Museum
  • Municipal Museum, Nagoya. Cast by Georges Rudier.


  • Pushkin Museum of Fine Arts, Moscow.


  • Waldmarsudde, Prins Eugens Museum, Stockholm. Purchased 1909. Cast by Hébrard.

United States


  • California Palace of the Legion of Honor, San Francisco. Purchased in 1915. Cast by Alexis Rudier.
  • Norton Simon Museum, Pasadena. Posthumous cast no. 11. Cast by Georges Rudier.


  • Colorado Savings and Loan Association, Denver. Posthumous cast. Purchased in 1966. Cast by Alexis Rudier.


  • City of Louisville. Lent to the University Foundry. Purchased in 1904. Cast by Hébrard.


  • Baltimore Museum of Art. Jacob Epstein Collection. Cast by Alexis Rudier.
  • Walters Art Gallery, Baltimore.


  • Detroit Institute of Arts. Purchased in 1922. Ex-collection of Dr. & Mrs. Linde. Cast by Alexis Rudier.


  • City of Kansas City. Located in front of the William Rockhill Nelson Gallery of Art.

New York

  • The B. Gerald Cantor Sculpture Center, New York City. Cast by Georges Rudier.
  • Columbia University, New York City. Cast by Alexis Rudier.


  • Cleveland Museum of Art. Gift of Ralph King in 1917. Cast by Alexis Rudier.


  • Museum of Fine Arts, Houston.
  • Rodin Museum, Philadelphia. Gift of Jules Mastbaum. Cast in 1928 by Alexis Rudier.

This list of other bronze casts of the enlarged version of The Thinker (130.2 × 140 × 200.7 cm) and their locations has been compiled from these sources:

DeCaso, J., and P. B.Sander. 1973. Rodin's Thinker: Significant aspects. San Francisco: Fine Arts Museum of San Francisco; Burlingame, Calif.: Demia Press.

Elsen, A.1985. Rodin's Thinker and the dilemmas of modern public sculpture. New Haven: Yale University Press. 163, 164.

Spear, A. T.1972. Rodin sculpture in the Cleveland Museum of Art. Cleveland: Cleveland Museum of Art. 96,97.

Spear, A. T.1974. Supplement to Rodin sculpture in the Cleveland Museum of Art. Cleveland: Cleveland Museum of Art. 130S.

Tancock, J. L.1976. The sculpture of Auguste Rodin. Philadelphia: Philadephia Museum of Art and David R. Godine. 121.


1. The remnant of a can of the Gorham AB Mixture remains in the Conservation Department although it has not been analyzed. The label reads, “A conditioning oil for bronze with either natural or oxidized finish,” and the instructions are, “Dampen cloth with oil and apply a liberal coating to entire surface. Wipe dry and polish with clean cloth.” The following note is also given: “AB Mixture will not restore original color nor prevent darkening. It will with repeated applications produce the beautiful color characteristic associated with well kept bronze.” The last sentence sounds as if it might have been written by Frank Purdy, as the language and view are similar to those expressed in his letters.

2. Sheath Rust Preventive, made by Birchwood-Casey, Eden Prairie, Minnesota, is according to in a product data sheet from the 1970s, a “solvent-based, water displacing corrosion inhibitor, finger print neutralizer and lubricant for ferrous and nonferrous metals. It lays down a thin, transparent film which lifts moisture from metal pores. Prevents corrosion by sealing moisture out with a continuous polar protective film …. Penetrates and loosens rusty ‘frozen’ parts. Leaves a slightly oily film which will not gum under high humidity, high-temperature conditions. Harmless to plastics, rubbers, paints. Contains no silicone or wax.” The product is still being marketed by Birchwood-Casey as Sheath RBI Water Displacing Rust Preventive, and the description has not changed in 20 years. The current material safety data sheet states that the product contains mineral spirits (over 63% w/w), heavy petroleum oxygenates, barium-neutralized (under 18% w/w), mineral oil (under 15% w/w), and propylene glycol monomethyl ether (under 4% w/w).

3. The x-ray diffraction pattern was found to match JCPDS file number 30–0473, International Centre for Diffraction Data, 1997.

4. Cheddite I.S. contains 90% potassium chlorate, 7% paraffin, 3% petroleum jelly, and traces of carbon black. Cheddite O.S. Contains 90% sodium chlorate, 7% paraffin, 3% petroleum jelly, and traces of carbon black. Cheddite O extra contains 79% sodium chlorate, 23.2% nitro derivatives of toluene, and 1.8% nitrocotton. Leonid Trassuk and Claude Blair, eds., The Complete Encyclopedia of Arts and Weapons (New York: Simon and Schuster, 1979), 174–77.


Chase, W. T., and N. F.Veloz. 1985. Some considerations in surface treatment of outdoor metal sculpture. AIC preprints, American Institute for Conservation 13th Annual Meeting, Washington, D.C.Washington, D.C.: AIC. 23–35.

CRM Bulletin. 1984. Outdoor sculpture in the park environment. CRM Bulletin7(2): 4–5.

Drayman-Weisser, T.1992. Dialogue/89—The conservation of bronze sculpture in the outdoor environment: A dialogue among conservators, curators, environmental scientists, and corrosion engineers. July 11–13, 1989, Johns Hopkins University, Baltimore. Houston: National Association of Corrosion Engineers.

Erhardt, D., et al. 1984. The durability of Incralac: Examination of a 10-year-old treatment. ICOM Committee for Conservation preprints, 7th Triennial Meeting, Copenhagen. Paris: ICOM. 84.22.1–84.22.3.

Merk-Gould, L., R.Herskovitz, and C.Wilson. 1993. Field tests on removing corrosion from outdoor bronze sculptures using medium pressure water. ICOM Committee for Conservation preprints, 10th Triennial Meeting, Washington, D.C. Paris: ICOM. 772–78.

Montagna, D. R.1989. Conserving outdoor bronze sculpture. Preservation Tech Notes. Washington, D.C.: National Park Service.

Veloz, N. F., and W. T.Chase. 1989. Airbrasive cleaning of statuary and other structures: A century of technical examinations of blasting procedures. Technology and Conservation (Spring): 18–28.

Weil, P. D.1975. The approximate two-year lifetime of Incralac on outdoor bronze sculpture. ICOM Committee for Conservation preprints, 4th Triennial Meeting, Venice, Italy. Paris: ICOM.

Weil, P. D.1980. The conservation of outdoor bronze sculpture: A review of modern theory and practice. AIC preprints, American Institute for Conservation 8th Annual Meeting, San Francisco. Washington, D.C.: AIC. 129–40.


DeCaso, J., and P. B.Sander. 1973. Rodin's Thinker: Significant aspects. San Francisco: Fine Arts Museum of San Francisco; Burlingame, Calif.: Demia Press.

Elsen, A. E.1980. In Rodin's studio: A photographic record of sculpture in the making. Oxford: Phaidon Press.

Elsen, A. E.1985. Rodin's Thinker and the dilemmas of modern public sculpture. New Haven: Yale University Press.

Elsen, A. E., ed.1981. Rodin rediscovered. Washington, D.C.: National Gallery of Art.

Spear, A. T.1972. Rodin sculpture in the Cleveland Museum of Art. Cleveland: Cleveland Museum of Art.

Tancock, J. L.1976. The sculpture of Auguste Rodin. Philadelphia: Philadelphia Museum of Art and David R. Godine.


Butcher's Bowling Alley Paste Wax (wax mixture in turpentine and petroleum naphtha)

Butcher Polish Co., 67 Foreft St., Marlborough, Mass. 01752

Incralac (Acryloid B-44 with benzotriazole and UV stabilizer)

StanChem Co., 401 Berlin St., East Berlin, Conn. 06023

Minwax Paste Finishing Wax (wax mixture in turpentine and petroleum naphtha)

Minwax Company, Inc., 16 Cherry St., Clifton, N.J. 07014, or, Flora, Ill. 62839

Orvus WA Paste (sodium lauryl sulfate)

Conservation Support Systems, P.O. Box 91746, Santa Barbara, Calif. 93190


BRUCE CHRISTMAN graduated from the University of Delaware/Winterthur Art Conservation program in 1979 and has worked as a conservator at the Cleveland Museum of Art. Currently he holds the post of chief conservator. Christman has been active in the Cleveland SOS! (Save Outdoor Sculpture!) program, helping to train volunteers for the project. The project has now moved to the next phase, which is to raise money for the treatment of the outdoor sculptures owned by the city of Cleveland. Address: Cleveland Museum of Art, 11150 East Boulevard, Cleveland, Ohio 44106–1797.

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Copyright © 1998 American Institute for Conservation of Historic and Artistic Works