JAIC 1997, Volume 36, Number 1, Article 5 (pp. 59 to 81)
JAIC online
Journal of the American Institute for Conservation
JAIC 1997, Volume 36, Number 1, Article 5 (pp. 59 to 81)



ABSTRACT—Puvis de Chavannes's allegorical murals, installed in the Boston Public Library between 1895 and 1896, were recently conserved by the staff of the Straus Center for Conservation as part of an ongoing major renovation of the building. The treatment of the murals included the consolidation of large areas of flaking paint, the reattachment of detached canvas sections, and the removal of tenacious surface grime. The opportunity to examine and analyze the Boston murals and to study archival material in France, as well as other murals there, has yielded interesting information about the materials and techniques Puvis used to create his highly individual and influential murals. The authors combine information about the Boston Public Library commission with the methods and materials used in the murals, the conservation treatment, and additional materials analysis.

TITRE—Les peintures murales allégoriques de Puvis de Chavanne à la bibliothèque municipale de Boston: Histoire, technique et restauration. RÉSUMÉ—Les peintures murales allégoriques de Puvis de Chavanne, intallées dans la bibliothèque municipale de Boston entre 1895 et 1896, furent récemment restaurées par le personnel du Straus Center for Conservation. Le traitement de ces peintures murales s'inscrit dans le cadre d'une rénovation générale du bâtiment, toujours en cours, et comprend la consolidation de zones importantes de soulèvements, la remise en place des sections où la toile s'était détachée et le nettoyage de la surface couverte d'une saleté tenace. L'examen et l'analyse de ces peintures murales, ainsi que l'étude de documents d'archives et de certaines autres peintures murales conservées en France, ont permis la mise à jour de renseignements intéressants concernant les techniques utilisées par Puvis pour créer ses peintures murales, si originales et si influentes. Les auteurs présentent des informations sur la commande de la bibliothèque municipale de Boston, les méthodes de travail et les matériaux employés dans les peintures murales, la restauration de ces peintures et les résultats de l'analyse d'autres matériaux.

TITULO—Los murales alegóricos de Puvis de Chavannes de la Biblioteca Publica de Boston: historia, técnica y conservación. RESUMEN—Los murales alegóricos de Puvis de Chavannes que fueron montados en la Biblioteca Publica de Boston entre los años 1895 y 1896, fueron recientemente conservados por el equipo del Centro Straus para la Conservación, como parte de la gran remodelación que se esta llevando a cabo en el edificio. El tratamiento de los murales incluyo la consolidación de grandes áreas de pintura que se habia escamado, la unión de secciones de lienzo desprendidas y la remoción de tenaz suciedad superficial. La oportunidad de examinar y analizar los murales de Boston, y de estudiar documentos pertinentes ubicados en archivos franceses, tanto como otros murales en Francia, produjo interesante información acerca de los materiales y las técnicas utilizadas por Puvis en la creación de estos murales muy particulares y trascendentales. Los autores combinaron información sobre la Comisión de la Biblioteca Publica de Boston con los métodos y materiales utilizados en los murales, el tratamiento de conservación y el análisis adicional de materiales.


The Boston Public Library (fig. 1) is one of the great Renaissance Revival buildings of America. Designed and built between 1888 and 1895 by the distinguished architectural firm of McKim, Mead, and White, the library remains an impressive testimony to the late-19th-century fashion for buildings both monumental in scale and eclectic in their architectural and artistic sources. The building embodies the impulse toward a cultural continuity that brought European civilization and the classical world to America. Its architects sought to unite the most celebrated artists of the day to accomplish this goal.

Fig. 1. The facade of the Boston Public Library, 1904. Courtesy of the Boston Public Library, Print Department

Pierre Puvis de Chavannes (1824–98), widely considered the greatest European muralist of the time, was the ideal candidate to decorate the grandest and most complicated space in the new library. By the 1890s he had painted most of his major mural decorations, including projects for the Pantheon and the Sorbonne in Paris, and for museums and municipal buildings in Lyon, Rouen, Amiens, Poitiers, and Marseille. Although in his youth he studied for brief periods in the studios of Eugene Delacroix, Thomas Couture, and Theodore Chasseriau, Puvis's individual style and technique were developed largely independently. Combining idealized classicism with simple flat designs and pale colors, his murals were in great demand.

From the beginning, the intention was that the library's imposing grand staircase and loggia be decorated with murals. Thus it was that in 1891 Charles Follen McKim traveled to Paris to engage Puvis's services. Convincing the aged painter to undertake the commission proved no easy task, but McKim was initially successful. Soon after, however, Puvis was awarded a commission for the Paris City Hall and had second thoughts about the American project. Another emissary was sent to Paris in 1892, and as a further inducement the artist was given a plaster scale model of the library's interior. Finally, on July 7, 1893, Puvis signed a contract for the murals that guaranteed him 250,000 francs, the equivalent of the then-unparalleled sum of $50,000. A year later, after completing the Paris City Hall project, the painter began working on the Boston murals and asked for more detailed measurements. He also requested, and was sent, a sample of the marble to be used in the staircase so that he might harmonize his palette with the surrounding architecture.

Puvis's oversized murals were executed on canvas in a specially designed studio at Neuilly, which included a two-story door (fig. 2)(Milner 1988). The Inspiring Muses was the first mural to be painted. It was exhibited at the Salon du Champs-de-Mars, then rolled and transported to Boston in October 1895, and finally mounted on the east wall of the loggia a month later (fig. 3). During the following year, the other eight panels were completed, exhibited in Paris, shipped, and installed (fig. 4). In fact, the artist himself never saw his works in situ. Their installation using a marouflage technique was overseen by Puvis's trusted collaborator Victor Koos. The arrival of the murals in Boston was met with much fanfare and celebration. In France, on the other hand, the art critic Gustave Geffroy expressed the feelings of many Frenchmen when he wrote:

It is a great shame to see these works go to the Boston Public Library, to faraway America. It is certain that many among us will never see them again. But, on reflection their going is to be admired: art crossing the globe, braving the waves of the ocean, to a new people, is a confirmation of one of its roles (Geffroy 1897, 148–49).

Fig. 2. The interior of Puvis's studio at Neuilly showing The Inspiring Muses before it was sent to Boston in 1895. Courtesy of the Trustees of the Public Library of the City of Boston

Fig. 3. The Grand Staircase of the Boston Public Library showing the loggia with The Inspiring Muses Acclaim Genius, Messenger of Light on the east wall

Fig. 4. North wall of the Grand Staircase with the murals Virgil, Aeschylus, and Homer. At the far left, the mural Physics can be seen on the west wall

So it was that Boston acquired the only murals by Puvis to be found outside of France.


The spaces to be decorated consisted of eight arched spaces above the library's grand staircase and a large, complex-shaped wall in the loggia. Puvis was given complete artistic freedom to create a narrative for the cycle. He described the theme for his mural program as a synthesis of the intellectual holdings contained in the Boston Public Library expressed in a symbolic framework. The mural in the loggia, titled The Inspiring Muses Acclaim Genius, Messenger of Light, is a summation of the entire schema.

The Inspiring Muses(fig. 3), the largest of the murals, covers 75.25 sq. m. (660 sq. ft.); it is 4.88 m (16 ft.) high and almost 15.42 m (50 ft. 7 in.) wide. Along the top of the wall, capitals and vault supports project downward, dividing the field into five tympana. At the bottom is a centrally placed door. Puvis expressed concern about the compositional problems caused by this setting and at the possibility of having to paint separate images to fill the space. He made numerous drawings and sketches and finally chose to unify the space with one continuous scene. Above the door, a winged boy representing the Genius of Enlightenment stands on a cloud with blazing lights in his hands against a pale yellow sky that extends across all five arches. Below the sky is an expanse of deep blue water, and below that oak and laurel trees are scattered over a green field dotted with flowering bushes. The nine Muses of Inspiration, representing the various divisions of literature and the arts (Esch 1982), float above the landscape, draped in white and holding lyres and laurel branches. On either side of the door Puvis painted stone statues representing Study and Meditation in grisaille.

For the eight paintings in the staircase, each 4.37 m (14 ft. 4 in.) high by 2.18 m (7 ft. 2 in.) wide, Puvis chose subjects that represent the various spheres of human knowledge. On the south wall he painted Philosophy, Astronomy, andHistory, on the north Pastoral Poetry (Virgil), Dramatic Poetry (Aeschylus) and Epic Poetry (Homer)(fig. 4), and on the west wall, on either side of the windows that open out onto the courtyard, he painted Chemistry and Physics.


Firsthand accounts of the materials and techniques Puvis used for the murals come primarily from the writings of his students and contemporaries as Puvis himself revealed very little. The observations of conservators and art historians, combined with recent scientific analysis, provide additional information that corroborates much of what was written during Puvis's time.

The preparatory studies and sketches Puvis created for the murals were an indispensable part of the final product; indeed, the sketches tell us most about his creative process. Prized in Puvis's day, many of the sketches for the Boston Public Library project were exhibited in the Salon of 1896. Geffroy reported that

the entire room behind the frescoes [murals] for the Boston Library is filled on all four walls with a series of drawings, an assemblage of research and studies…. There are pencil, pen, and pastel sketches; detailed studies showing patient draftsmanship, balanced panels which are as beautiful as paintings: powerful sketches, harmonized by the rhythm of the lines (Geffroy 1897, 167).

Today, sketches for the library murals are preserved in numerous private and public collections. The Cabinet des Dessins at the Louvre houses five related works. Two of the small compositional studies, both about 10 x 33 cm (4 x 13 in.), are in ink over pencil on tracing paper. They reveal that Puvis did not at first conceive of the Muses as figures floating over the landscape but as figures standing firmly on the ground. In a third study at the Louvre (RF23070), Puvis raised the Muses as in the final design. This change was made so that the figures would not be truncated by the solid balustrade when seen from halfway up the staircase (Price 1994, 230).

Puvis drew hundreds of life drawings from models in his studio. He used distillations of these sketches, squared up and transferred, for the figures in the murals. A drawing for one of the Boston Public Library Muses (the second figure from the left in The Inspiring Muses) reveals that Puvis carefully worked out the pose of the figure in a nude sketch (Petit Palais, P.P.D 274.1) before draping her in a robe in another sketch of the same size (Lyon Inv. B607–28). Puvis also made numerous small color studies for each mural project. He rendered his color ideas for the library murals in various media. In a study for Physics he painted in gouache on cardboard. Some sketches for the Muses were executed in oil on canvas, others in watercolor.

The final step in the preparatory process was the creation of a full-scale painted cartoon combining many of the earlier studies. According to Puvis's student and collaborator Paul Baudouin, the cartoons Puvis produced for his mural projects “were very precise and studied works, in which all of the values were expressed” (Baudouin 1935, 300). Baudouin also noted that Puvis used either paper or canevas (a French word describing a coarse, light-colored cloth used for tapestry making) as a support for his large-scale cartoons. Notations on a photograph taken while the cartoon for the Inspiring Muses was on exhibit in the Salon of 1920, in the files of the Musée d'Orsay, indicate that the cartoon was painted in gouache on paper. The present whereabouts of the cartoon are unknown; its last location was in the attic of the Comic Opera, Paris (d'Argencourt et al. 1977, 231).

Puvis executed the Boston murals on a plainweave linen canvas, typical of the type he generally chose for his monumental wall decorations. In the library murals the coarseness of the canvas is evident in many thinly or dryly painted passages. Puvis had access to immense canvases. Only two pieces of linen were used for The Inspiring Muses, each one measuring 4.88 m (16 ft.) high with the left half 8.81 m (28 ft. 11 in.) long and the right half 6.60 m (21 ft. 8 in.) long. If seams were necessary in his large mural projects, Puvis did his best to camouflage or hide them. In the huge Sorbonne mural, The Sacred Grove (1886–89), for example, the two seams coincide with vertical tree trunks. For The Inspiring Muses, Puvis located the join of the two canvases above the central loggia door, where it is least likely to be noted from the floor below (a device he also used for Ave Picardia Nutrix [1865] in Amiens). The seam is to the right of the figure of Genius, where the height of the canvas is minimal.

Due to the light, unsaturated colors and almost matte surfaces of Puvis's murals, many people—beginning with the critic Théophile Gautier—have mistakenly referred to them as frescoes (Gautier 1861, 102–6). In fact, he appears to have experimented only once with pigments bound in lime on plaster. These works were painted (ca. 1853–54) at Le Brouchy, his brother's home outside of Lyon. Executed on an exterior wall, the paintings are now badly weathered.

Puvis's success in achieving a frescolike appearance for his murals using oils can be explained by the combination of several techniques, starting with his grounds. Each library canvas was primed with a fairly thin ground layer of white chalk in a glue medium (see appendix 1). Various authors have described Puvis's grounds with the French term plâtre (plaster), which refers generically to any sort of plaster, including lime and, hence, chalk. Grounds composed of chalk and glue have been found on most of Puvis's murals analyzed to date (Galinier 1995). The role of the ground in soaking up excess medium was duly noted in Puvis's time. According to one author, it was this highly absorbent ground “which gives his work that dead surface” (Hamerton, quoted in Crowninshield 1887, 105).

Two of Puvis's contemporaries also suggest how he achieved the particularly frescolike appearance in his use of oil paints. According to the painter Frederic Crowninshield (1887), he deadened his oils by adding spirits of turpentine. Paul Baudouin (1935) writes that Puvis drained his oils by placing them on papier buvard (blotting paper). Baudouin also states emphatically that Puvis never added anything to his paints (no siccatives, copal, varnish, or any other ingredient). Each of these techniques, combined with the fond maigre (absorbent ground), would obviously produce a lean, matte paint with little if any excess oil.

According to one contemporary observation, Puvis painted in “common oil-paints” (Crowninshield 1887). This fact was confirmed by the discovery of some of Puvis's leftover paint tubes in a paint box preserved by the artist's heirs at Le Brouchy (fig. 5). A list of the various colors found in the paint box is included in table 1. Puvis purchased paint from several different colormen and paint manufacturers in Paris. The tubes are tin with metal screw caps, which would date them after 1865 when screw caps began to replace the corks previously in use (Lefranc and Bourgeois 1990)(fig. 6). A box of six tubes is labeled “Exposition Universelle de 1889 Grand Prix.” Some of the tubes (from Gay and Lefranc) are labeled “ground in oil” while those from Bourgeois Ainée are a “new preparation for painting in gouache.”

Fig. 5. Puvis de Chavannes's paint box at Le Brouchy. Courtesy of the Straus Center for Conservation

Fig. 6. Paint tubes from Puvis's paint box at Le Brouchy. Courtesy of the StrausCenter for Conservation


Numerous authors have also suggested that Puvis achieved a matte appearance by adding wax to his painting medium. By the late 1840s, the use of wax was commonplace in French mural painting. Delacroix (at St. Sulpice), Hippolyte Flandrin (at St. Germain-des-Près), and Chasseriau (at St. Roch) all painted à la cire(Baudouin 1914). In this technique, wax was either saponified with lime or dissolved in mineral spirits, making it usable without heat (Béguin 1981). According to his student Lasalle-Bordes, Delacroix added small amounts of wax to the oils on his palette as he worked at L'Assemblée Nationale (Sérullaz 1995). There is no documentary evidence that Puvis mixed wax with his oils in this manner. Indeed, no wax was detected in the two samples from Puvis's Boston murals analyzed with gas chromatography (see appendix 1). Furthermore, solubility problems were not encountered during the conservation treatment of the murals. Wax was also not detected in samples taken from Puvis's murals at Rouen. Other works by Puvis have, however, been found by analysis to contain a wax component (Galinier 1995). This inconsistency in the use of wax has at least two possible explanations. Either Puvis added wax to his medium in some works (perhaps especially his earlier paintings) but not others, and/or wax was present as a component in some of the paint he purchased commercially. Analysis of four samples from the paint found in Puvis's paint box confirms that the latter theory is possible. Two of the samples contained wax, while the other two did not (see appendix 1).

Puvis may or may not have been aware of the wax component in the tubes of paint he purchased. One of the samples that contained wax is from a tube labeled “ground in oils” and gives no indication of any wax additive. Carpentier (1875), among others, warned against mixing wax and oil because the wax stops the oil from drying and the oil stops the wax from hardening. By 1897, Lefranc advertised an oil paint that was “completely solid” containing “not an atom of wax” (Lefranc and Cie 1897). We can assume, therefore, that by the end of the 19th century, fewer and fewer color manufacturers added wax to their oils.

To imitate the pale colors of fresco in his murals, Puvis painted in a very light key within a narrow tonal range, “renouncing all the effects of depth belonging properly to oil” (Hamerton 1882, 336). Puvis was accused in his own day of starting “a contagion of white” (quoted in Price 1977, 25). Lead white was found as a major component in every layer of paint sampled at the Boston Public Library (see appendix 2). Puvis kept the range of colors simple, limiting the number of pigments used in each work and using them consistently within each painting. He likely achieved this harmony in a process, described by his student Baudouin, of mixing large amounts of “mother tones” (tons mères) in bowls (assiettes creuses) that he kept submerged in water so that they would not dry out (Baudouin 1935, 302).

Puvis applied paint in a direct manner, often using just one or two layers. No glazes were observed in the murals, and only one of the numerous cross sections taken revealed a third layer. He textured his paint by various means: thick, dry impastos; thin, lean layers revealing the coarse texture of the canvas; passages of thick paint scraped flat; and incisions and scratches inscribed with various pointed tools or spatulas. Puvis also left some areas of canvas uncovered, especially outlining figures and trees, which often reveal what appears to be a charcoal underdrawing. The very few pentimenti visible in the Boston murals may well be explained by his thorough preparation or by his practice of scraping off unwanted passages rather than painting over them. Puvis recommended this practice to his followers: “Be fearful of useless impastos which darken, turn bluish and heavy. When you have painted a passage that you dislike, wait until it is possible to remove it. Judge it and if it is condemned, scrape it off firmly with a palette knife…. Excess paint is an abomination. In twenty four hours the gold will change to lead” (quoted in Vachon 1895, 57).

It is highly unlikely that Puvis applied a varnish to his mural works. Ultraviolet light examination of his first mural cycle located at Le Brouchy has revealed that as early as the 1850s, Puvis chose not to apply a final varnish coating. The recent treatment and analysis of the Boston murals detected no original resin coating. As with many other questions of technique, Puvis appears to have written nothing at all about varnishing his paintings. His student Baudouin, who notes that Puvis never added varnish to his paint mixtures, also makes no mention of varnishing and adds that Puvis's Childhood of St. Genevieve (1876) in the Pantheon “gives the total illusion of frescoes” (Baudouin 1935, 300).

The use of all these techniques produced the frescolike appearance so sought after by Puvis. He firmly believed that murals should not dominate an architectural space. To that end, he created paintings with minimal illusionistic depth by using light colors with unsaturated and unvarnished surfaces. Puvis chose colors that would harmonize with the library's marble staircase, and he flattened the figures and other elements to emphasize the two-dimensional nature of the wall.

In Boston, as in France, Puvis's gigantic canvases were mounted to the wall using marouflage. The technique of affixing oil paintings on canvas to a wall or ceiling originated in 17th-century France (Mora et al. 1984). Thus the artist could work in the comfort and privacy of his studio, surrounded by his own paraphernalia. When the painting was finished it was usually rolled and delivered to the site for installation by a mural hanger. In French, maroufle refers to the sticky remnants of paint left in an artist's pots. The adhesive typically consisted of oils, resins, and fillers mixed into a thick paste. By the beginning of the 19th century, céruse (lead carbonate) was added to speed up the drying process (Mora et al. 1984, 157). For Puvis's murals at the library, lead white was a major component in the mounting adhesive. Although Puvis was not involved in the Boston installation, he did personally supervise the marouflaging of many of his murals in France. Paintings marouflaged with lead white paste are extremely durable and often show no signs of cracking.

Puvis's murals in Amiens and in the Boston Public Library were attached by first priming the wall with an isolating layer of lead white in oil (d'Argencourt 1973, 253). When the primer had dried, both the wall and the back of the canvas were coated with a layer of the marouflage paste. The canvas was then attached using hand rollers to work out wrinkles, air pockets, and excess paste (Mayer 1957, 34). The task of mounting an immense canvas such as The Inspiring Muses was obviously not without problems. Although very close, the huge canvas did not register exactly, especially in the arches where portions of the tacking margin were used to extend the canvas. Air pockets that formed during the installation were slit open and additional adhesive was inserted. Along some of the canvas edges, metal tacks were driven through the painting to ensure contact while the adhesive dried. These edges, together with the extended edges in the arches, were repainted in oils, most likely by Victor Koos after the installation.


Documentary evidence indicates that Puvis's murals were restored on at least three previous occasions. The first documented treatment occurred in 1930 when they were cleaned and coated by Charles Durham. Commenting on that early restoration, Edward Forbes wrote that “the protective surface that was put on … was a mixture of the white of egg combined with some other ingredients, which makes a sort of varnish and has given the paintings a slight gloss” (Forbes 1940). In 1940, the restorer R. Arcadius Lyon cleaned the murals with a weak solution of castile soap (sodium carbonate and olive oil) and water. At that time he found that the previously applied egg white coating was tough and well adhered and that it did not respond well to his cleaning efforts. Fearing possible damage to the paint layers, he chose not to try stronger cleaning solutions and decided to leave the coating on the surface (Forbes 1940). Finally, Finlayson Brothers restored the murals in 1953, but they do not appear to have left any documentation of the treatment.

As part of a major restoration program for the library, the murals were scheduled for conservation in 1994. They were generally in a very good state of preservation but did require surface cleaning, consolidation of minor flaking, and retouching of minor abrasions. During the early phase of the renovation, however, an unfortunate event necessitated the immediate conservation treatment of The Inspiring Muses. In the early morning hours of February 3, 1992, the painting was badly damaged by water condensing on its surface as a result of an accidental steam valve release. Fortunately, the other eight murals on the staircase were not damaged, as they had been covered with multilayer barriers to protect them from the renovation work. Kate Olivier, who was the first conservator from the Straus Center for Conservation to arrive at the scene, found the area still full of hot, white steam and described it as “like being in a Turkish bath.” The first RH reading, taken that morning shortly after 9:00 a.m. was 87%, but it surely must have been very near 100% earlier that morning. Fans were installed in the staircase windows to extract the damp air. By midafternoon the RH had dropped to 77%, and by the next morning it had dropped to 55%. Later, a protective polyethylene barrier was draped around the scaffolding in front of the mural, and humidifiers were placed in the enclosure to control the humidity level.

The steam caused three specific types of damage. The most serious was extensive lifting and tenting of the paint layers that affected approximately 40% of the painting (fig. 7). Most of the damage occurred on the right half of the mural; fewer and smaller sections were affected on the left half. Why this occurred is not entirely clear, but a likely explanation is that variations in air currents increased the amount of water condensation on the right. Fortunately, the canvas did not shrink very much because of its strong attachment to the wall. The areas of lifting varied in severity over the surface of the painting. The worst damage occurred along the bottom edge, where most of the water collected, and in the blue areas on the right side of the mural. There was moderate flaking in the middle section and minor flaking in the upper section. Generally, the white paint layers exhibited less damage because of their greater thickness and the slow absorption of water by lead white. In spite of their critical condition, the paint layers remained surprisingly intact with very few visible losses. A second serious consequence of the water condensation was overall blanching and the formation of dark vertical stains over much of the paint surface. As the warm water ran down the mural, it dissolved surface material that was re-deposited and dried in the form of disfiguring drip marks (fig. 9). The third problem encountered was the detachment of small areas of canvas from the wall (fig. 11). These areas were located near the bottom of the mural where the water had collected and in six of the cuts made by the mural installation crew in 1895.

Fig. 7. Detail of an area of tented cleavage caused by steam damage in The Inspiring Muses. Courtesy of the Boston Public Library. Before treatment

Fig. 9. Detail of stains and drip marks on The Inspiring Muses. Before treatment

Fig. 11. Detail of detached canvas around an original installation slit in the arm of one of the Muses, before treatment. Also visible is the extensive cleavage in the surrounding paint layers.

Given the urgency of the situation, consolidation tests were begun immediately. Access to the entire surface of the mural was provided by the fixed scaffolding that had been installed for other renovation activities. Of the many adhesives considered, the two adhesives finally selected for testing on the mural were sturgeon glue and BEVA 371. Both were effective in readhering the paint layers. The BEVA 371, however, held the flaking paint more effectively during the removal of the excess adhesive. In addition, it would not be affected by water-based cleaning solutions that would later be required to remove the surface grime and stains; it would not cause further canvas shrinkage during application; and it would be less affected by fluctuations in temperature and relative humidity.

The BEVA 371 adhesive, diluted (1:1) in benzine and heated to increase its flow and penetrating properties, was applied to the affected areas with sable brushes. Because of the vertical surface, the adhesive did not always flow easily under all of the flaking paint. To assist penetration into difficult areas, benzine was lightly sprayed onto the paint surface to wet it out before applying the BEVA 371. Two or three applications of the adhesive were required in most areas to ensure adequate consolidation. The BEVA 371 was allowed to dry at least 24 hours prior to paint reattachment using Willard heated spatulas. The severity and extent of the flaking over the mural made this a difficult and lengthy procedure, but in the end the paint layers were successfully readhered (fig. 8). Then a xylenes/water emulsion was applied by brush to remove the excess BEVA 371 adhesive (for the formula, see appendix 3). The emulsion and the gelled and partially dissolved BEVA 371 were then lifted from the paint surface with dry cotton wads. This procedure reduced the amount of solvent penetrating into the paint layers that might otherwise have dissolved the adhesive. The emulsion had the added advantage of removing some of the less tenacious grime layers. To eliminate the possibility of continued solvent action on the paint layers, the emulsion residues were rinsed several times with water-moistened cotton wads. Once dry, the paint surface was rinsed with benzine and cotton wads.

Fig. 8. Detail of The Inspiring Muses. Scale is 1:1 with fig. 7. After treatment

After the consolidation was complete, the fixed staging was replaced in favor of rolling scaffolding, which allowed more flexibility and the ability to view the work as a whole. The steam had completely disrupted the grime layers and surface coating (fig. 9). Even before the steam damage occurred, the surface grime was known to be difficult to remove, t attempts to clean the mural were further complicated by the redeposited drips. Coating samples were analyzed with Fourier transform infrared spectroscopy (FTIR), and distinct amide groups for protein were found (see appendix 2). The source of the amide groups is most likely the egg white coating that was applied in the early restoration but could possibly be a component of animal glue extracted by the steam from the canvas support. To date, no further analysis has been carried out on these samples. Numerous cleaning solutions and solvents routinely used in painting conservation were tested without success. A cleaning solution recently devised by Richard Wolbers was tried and, unlike the others, gave very encouraging results. The effectiveness of this solution was confirmed by an ultraviolet fluorescence staining analysis undertaken by Wolbers (see appendix 3). Further testing indicated that if the solution were used in a controlled manner, the surface grime and blanched remnants of egg white coating could be effectively and safely removed. The solution also caused no noticeable blanching of the paint layers, a finding that had important implications for 74 later decisions concerning the possible application of a protective coating. The solution was a citrate and detergent gel, buffered to a pH of 8.5 (for the formula, see appendix 3). The cleaning gel solution was brushed onto the mural and gently worked over the surface for approximately 10 to 15 seconds (fig. 12). Much of the grime and staining was dislodged during this first application, which was removed from the paint surface with large dry wads of cotton. Several more applications of the gel were required to remove the grime and surface coating remnants (fig. 13). Finally, the mural was rinsed several times with water followed by petroleum benzine (fig. 10).

Fig. 10. Detail of The Inspiring Muses. Scale is 1:1 with fig. 9. After treatment

Fig. 12. Catherine Rogers applying the diammonium citrate gel solution on the surface of The Inspiring Muses

Fig. 13. Detail of The Inspiring Muses during the removal of surface grime and stains

A number of conservators and conservation scientists have expressed concerns about the use of some of Wolbers's cleaning solutions. They question the solubility effects of various components on the paint layers, the difficulties of clearing surface residues, and the long-term effects of residues that might remain on the paint layers. These issues led to repeated, painstaking rinsing of the mural surface. Given its size and the quantities of cleaning solution used, it is still possible that some residues remain. However, no other cleaning solution was found to remove the accumulated grime and staining.

In the white drapery of the Muses the redeposited accretions and streaks were also removed, but it became evident after cleaning that the paint layers had been darkened slightly by the condensing steam. While the nature of this darkening effect was not determined, possible causes include: (1) the conversion of lead carbonate into lead sulfide, which is typically seen in fresco paintings, (2) the much rarer conversion of lead carbonate into lead dioxide (Gettens et al. 1967), and (3) the recrystallization of the lead carbonate, which would give it a darkened appearance. Attempts were made to convert what was thought to be darkened lead sulfide into lead sulfate (white form) using hydrogen peroxide. The very limited success of this procedure suggested that lead sulfide was not present, and this conclusion was later confirmed by analysis.

The detached canvas areas were plasticized by the application of local moisture and pressure. To apply the necessary pressure, a jig made from a veneer press was secured to the scaffolding using C-clamps (fig. 14). Dampened blotters, sections of foam (to allow the blotter to conform to the distortion), and a Masonite board were placed against the delaminated canvas, and gentle pressure was exerted. After some 40 minutes the paint and canvas were sufficiently plasticized, and the dampened blotters and foam were removed. They were replaced with dry blotters, a 1/4 in. thick Ethafoam section, and a Masonite board and left in place overnight to allow the canvas to dry flat. The detached canvas was then readhered to the wall with Jade 403 (polyvinyl acetate emulsion), and the adhesive was allowed to set under the pressure of Mylar, blotters, and Masonite board for 24 hours. Although Jade 403 is basically an irreversible adhesive, it is sufficiently weaker than the lead white paste and was chosen for its strength and flexibility.

Fig. 14. Pressure jig applied to the arm of a Muse to readhere a pocket of detached canvas (see fig. 11 for detail)

In comparison to the scale of the mural, the losses were small and relatively few. Filling of the losses was not necessary since they occurred in the thinnest paint layers and thus would not be noticeable from a normal viewing distance. The losses and irreversible remnants of the drip marks were inpainted with Bocour Magna Colors (fig. 15). These paints were chosen for their reversibility and appropriate degree of opacity to match the original colors. Although the colors have been discontinued, the Straus Center for Conservation still has a full complement. Retouchings that dried too matte were glazed and adjusted with Acryloid B-72 in xylenes.

Fig. 15. Detail of one of the nine Muses after inpainting

Once conservation of The Inspiring Muses was completed, treatment proceeded on the other eight murals in the staircase. Apart from Philosophy, which has had a history of structural problems, these murals were in good condition and required very little consolidation. Surface grime was thick throughout, but especially obscuring in the murals nearest the windows (fig. 16). The consolidation, cleaning, and retouching of these murals was carried out using the same methods and materials described for the treatment of The Inspiring Muses.

Fig. 16. Aeschylus during the removal of surface grime

Although the Boston murals were not originally varnished, consideration was given to the possibility of applying a protective coating. Issues of public accessibility, vandalism (thus far not a problem), and the redeposition of grime were the main concerns. Natural resins and most synthetics were considered but rejected because of their high saturating properties and poor aging characteristics. Acryloid B-72 was chosen for testing because of its stability and lower saturating properties. It was applied by brush in concentrations ranging from 2 to 6% in xylenes. It was clear to conservators and art historians who were consulted that varnishing would impart far too much saturation and gloss to be aesthetically acceptable. Another concern was the solubility effect that aromatic hydrocarbon solvents would have on the BEVA 371 that was used to consolidate the paint layers should it become necessary to remove the varnish in future treatments. Furthermore, Puvis's clear desire for a matte surface dictated that the murals should remain unvarnished. After the grand staircase was reopened to the public, low display cases were placed against the dado below The Inspiring Muses to create a partial barrier between the mural and visitors to the library.


The conservation decisions that were reached were based on the scale and urgency of the problems faced. Using the citrate and detergent gel solution proved to be the safest and most effective way of removing the surface grime and the worst effects of the stains and drip marks. Although concerns about the effect of this solution on paint layers should not be ignored, in this instance its positive attributes were decisive. An important factor was that it caused no blanching, thus eliminating the need for varnish.

Puvis's skillful and remarkable integration of a mural cycle into a complex space for a building he never saw is a testament to his unusual abilities. While it is recognized that Puvis's images had a significant influence on 20th-century painting, the impact of his highly individual painting technique has not been adequately acknowledged. Painting in oils on canvas, he combined various methods and materials to imitate the matte appearance of frescoes. He used coarse canvases, absorbent grounds, drained oils, pigments mixed with large amounts of white, and a variety of texturing techniques. Contrary to common practice in the first half of 19th-century France, he did not add varnish and other ingredients to his medium, nor did he apply a final varnish coating to his murals. His role in the introduction of these innovative techniques, which became common practice in this century, warrants further investigation.


ACKNOWLEDGMENTS The authors are greatly indebted to Richard Newman, who analyzed the binding media and compiled appendix 1, and to Richard Wolbers, who produced appendix 3 and without whose research the treatment of the murals would not have been so successful. We are also extremely grateful to David Bomford, Yvonne Hoppenot, Hayden Maginnis, Anne Roquebert, Hubert de Truchis de Lays, Amy Snodgrass, and especially Aimée Brown Price for their invaluable support and assistance. For their tireless work, enthusiasm, and efficiency we would like to thank our conservation colleagues Nancy Buschini, Lenora Rosenfield, Danica Stojkovikova, Lydia Vagts, Nancy Garrison, and particularly Catherine Rogers, who was indispensable throughout the entire project. Finally, we would like to acknowledge the support of the Boston Public Library and the architectural firm Shepley, Bulfinch, Richardson, and Abbott, and to thank the National Endowment for the Arts for funding the professional development grant.

Photographs are reproduced courtesy of the Trustees of the Public Library of the City of Boston and the Boston Public Library, Print Department.




1.1.1 Ground

A sample of the ground was hydrolyzed, derivatized with phenylisothiocyanate, and analyzed for amino acids by high-performance liquid chromatography (HPLC) following Waters Chromatography “Pico Tag” method. Analyses were carried out on a Waters instrument that consisted of two 510 pumps, a manual injector, and 991M photo diode array detector. The amino pattern closely matched that of collagen, with the exception of considerably reduced glutamic and aspartic acid levels; these amino acids are typically lost during sample preparation when calcium carbonate is present, as was the case in the ground sample (Halpine 1992). Another portion of the ground was saponified in 10% KOH in methanol, the solution neutralized and then extracted twice with ether. Ether extracts were combined, evaporated to dryness, redissolved in a small amount of methylene chloride, and methylated with 10 μl dimethylformamide dimethyl acetal (Pierce Chemical Co.). Analysis was carried out by gas chromatography—mass spectrometry (GC-MS) on a Hewlett Packard 5890 capillary gas chromatograph equipped with an HP 5971A mass selective detector. The sample was found to contain traces of palmitic and stearic acids, which are typical contaminants in animal glues. It is also possible that these fatty acids came from the overlying oil paint layer.

1.1.2 Paint Binder

Two samples were saponified and analyzed by GC-MS as described above. While traces of hydrocarbons were detected, such as those characteristic of hydrocarbon waxes such as ceresin, the very low levels suggest that they may simply be contaminants in the oil and not indicative of wax intentionally added by the paint manufacturer. Traces of methyl dehydroabietate, an oxidation product commonly found in aged pine resins, were also detected in the two samples. The level was extremely low, so it cannot be concluded that pine resin was an intentional component of the paint. Ratios of the C9 and C8 dicarboxylic acids (diC9/C8) suggest that the oil was not heat-bodied. The palmitic/stearic acid ratios (P/S) are somewhat high for linseed oil; possibly the oil was walnut or a mixture of linseed and poppyseed. Poppyseed was identified in all four samples from the tubes of paint (see next section).

1.1.3 Tube Paints

Four partially dried samples from tubes preserved from Puvis's studio by his heirs were analyzed by GC-MS as described above. The oil in each appears to be poppyseed, based on the high palmitic/stearic acid ratios (P/S). Two samples contained substantial amounts of straight-chain hydrocarbons in the C22-C32 range, maximizing at C26. This hydrocarbon pattern is typical of ceresin wax. The results were as follows (when two analyses were carried out, P/S ratios from both are given):



2.1.1 Pigments

Nine paint samples were selected for analysis, including two greens, one red, four blues, and two whites. Cross sections of the paint samples were examined using a Leitz Laborlux biological microscope fitted with visible and ultraviolet light sources. The cross sections were prepared by imbedding the paint samples in cubes of bioplastic polyester resin, which were subsequently cut and polished with micromesh polishing cloths to reveal the structure of the paint layers. The cross sections were analyzed for their elemental composition using a JEOL 6400 scanning electron microscope with a Noran Instruments Z Max 30 Series light x-ray energy dispersive x-ray spectrometer (SEM-EDX). Sample sites were analyzed for 100 counts at an accelerating voltage of 20 kilo electron volts (keV). Standardless quantitative analysis was performed by the calibrated voyager quantitative microanalysis system using ZAF matrix corrections. Fourier transform infrared microspectroscopy (FTIR) was performed using a Spectra-Tech IR-Plan microscope attached to a Nicolet 510M spectrometer with an auxiliary MCT detector. Samples were mounted for analysis on a Spectra-Tech Micro Sample Plan fitted with a diamond window, and data were collected for 200 scans at a spectral resolution of 8 cm−1. The resulting spectra were viewed in absorbance mode between 625 and 4000 wave numbers, and for consistency the CO2 peak was removed and the spectra were baseline corrected.

Pigments were identified by microscopy and SEM-EDX (see table). Analyses showed that lead white was used throughout the painting as highlights and aa matrix for the colors. For example, the highlight from The Inspiring Muses is lead white over a gray layer composed of lead white modified with ultramarine, red oxide, emerald green, and carbon black. The principal green pigments used were emerald green (copper aceto-arsenite) and green earth (hydrous iron, magnesium, and aluminum potassium silicate). Emerald green was found in the grass of Philosophy and in the initial green layer of the foreground of the Muses, together with green earth. The upper layer of the foreground of the Muses contains particles of green earth in a lead white matrix. The principal blues found were cobalt blue (cobalt aluminate) and synthetic ultramarine (sodium aluminum silicate). The water for the Muses was ultramarine mixed with lead white, black, and red in one simple layer. The blue sky in both Chemistry and Aeschylus is cobalt blue mixed with lead white. The blue water of Aeschylus was applied in two layers: ultramarine blue and lead white overlaid by cobalt blue and lead white. Four reds were identified: vermilion (mercuric sulfide), red lake on an aluminum substrate, red ochre, and red lead. History's red robe is built up from a layer of lead white and red ochre followed by a layer containing lead white, calcite, and vermilion. Red lake was found as a minor component of the green grass in the Muses.

The yellowish white ground was identified by SEM-EDX and FTIR as chalk with a proteinaceous binding medium. A small amount of oil was also identified in the ground, which could account for the yellow color of the ground.

2.1.2 Marouflage Adhesive

The marouflage adhesive, which holds the canvas onto the wall, was analyzed by SEM-EDX and FTIR. The sample showed absorbances for lead white, oil, and lead carboxylate (a byproduct of the aging of lead white in the presence of oil).

2.1.3 Drip from Surface of The Inspiring Muses

A drip stain was sampled from the surface of the Muses. FTIR analysis showed major absorbances for protein and lead white. There was a minor absorbance at 1076 wavenumbers that was unidentified.



Samples of The Inspiring Muses were taken in an attempt to characterize the drip and stains and the accumulation of grime on the surface of the paint. Samples were also taken from similar areas before and after grime and accretion removal tests to evaluate the effects of the cleaning solution. These were mounted in Ward's Bioplast and sent to Richard Wolbers for ultraviolet fluorescence analysis and photomicrography. Twelve samples were viewed and photographed in the following sequence: normal light, UV only, UV stained with 4% triphenyl tetrazolium chloride in methanol (TTC), UV stained with .25% rhodamine isothiocyanate in acetone (RITC), and UV stained with .20% rhodamine 123 in acetone (RHO 123).

The results of the examination can be summarized as follows:

3.1.1 Samples of Paint with Surface Bloom but No Deposit from Steam Drips

Boston Public Library (BPL) 1. Green paint. The green paint stained with RHO 123 (for oils) and with TTC (carbohydrates), signaling both materials and therefore potentially water soluble components in the binder. Apart from a single droplet of a noncharacterized material (negative staining with the stains listed above) and a substantial and continuous grime layer, no other surface-accumulated materials were observed.

BPL 3. White paint. The white paint stained only lightly with RHO 123. Little accumulation of grime was noted on the surface, which was slightly autofluorescent, indicating normal aging on the surface.

BPL 5. Blue paint. The blue paint stained RHO 123 positive (oil), but, as in sample BPL 1, there was a slight reaction with TTC (carbohydrate) as well. The surface is obviously aged (autofluorescent) and grime-laden, but no additional deposits were noted on the paint surface.

3.1.2 Samples of Paint with Deposits from Steam Drips

Three samples of the green, white, and blue paint (BPL 2,4, and 6) all exhibited obvious autofluorescent “deposits” along the surface and above the grime layer under UV light. The morphology of the deposited materials was noncrystalline (organic) in nature and may have signaled the extraction and redeposition of a discrete layer of polar organic material. However, this material was negative for all of the applied stains.

3.1.3 Samples of Paint After Cleaning with Wolbers Diammonium citrate-chelating/ionic strength solution

Three samples of the green, blue, and white paint (BPL 7, 8, and 9) all showed undisrupted surfaces after cleaning with Wolbers's diammonium citrate-chelating/ionic strength solution.


Xylenes/water emulsion formula (for the removal of BEVA 371 adhesive and less tenacious grime layers):

50 ml xylenes, 20 ml Triton X-100, 30 ml water, 2 ml triethanolamine (the aqueous phase was adjusted with dilute HCl acid to a pH of 8.5 prior to emulsification)

Diammonium citrate-chelating/ionic strength solution (for the removal of surface grime and stains):

100 ml water, .5 g deoxycholic acid, 5 ml triethanolamine, 1 g ammonium chloride, 1 g diammonium citrate, .05 g Triton X-100, 1.5 g hydroxypropyl-methyl-cellulose (adjusted with HCl acid to a pH of 8.5)


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BEVA 371

Conservator's Products, P.O. Box 411, Chatham, N.J. 07928

Acryloid B-72

Rohm and Haas Co., Philadelphia, Pa. Supplied by Conservation Materials, 1165 Marietta Way Sparks, Nev. 89431

Deoxycholic acid Triethanolamine Citric acid-diammonium salt Triton X-100 Hydroxypropyl-methyl-cellulose Triphenyl tetrazolium chloride (TTC) Rhodamine isothiocyanate (RITC)

Sigma Chemical, P.O. Box 14508, St. Louis, Mo. 63178

Ammonium chloride

Mallinckrodt Specialty Chemicals, Paris, Ky. 40361

Hydrochloric acid (reagent A.C.S.)

Fisher Scientific, Springfield, N.J. 07081

Mylar (.0005 in.)

Talas, 213 West 35th St., New York, N.Y. 10001

Magna Colors

Bocour Artists Colors, New York, N.Y. 10019

Willard heated spatula

Willard Developments, Leigh Road, Chichester, West Sussex P019 2T3, U.K.

Rhodamine 123 (RHO123)

Kodak Laboratory and Research Products, Rochester, N.Y. 14650


TERI HENSICK has been a paintings conservator at the Straus Center for Conservation, Harvard University Art Museums, since 1980. She holds a B.A. (Phi Beta Kappa) in art history from Wellesley College and trained in paintings conservation in Florence (Universita Internationale dell'Arte), Zurich (Swiss Institute for Art Research), and Nuremberg (Germanisches Nationalmuseum). She interned in paintings conservation at the Harvard University Art Museums in 1976–77 and was assistant and subsequently associate conservator of paintings at the Detroit Institute of Arts from 1977 to 1980. In 1995 she spent two months in France researching Puvis de Chavannes's materials and techniques with the support of a National Endowment for the Arts professional development grant. Address: Straus Center for Conservation, Harvard University Art Museums, 32 Quincy St., Cambridge, Mass. 02138.

KATE OLIVIER received her training at the Courtauld Institute of Art from 1962 to 1965. She worked for six months in Florence following the flood in 1966 and one year in Venice on paintings by Tintoretto. As a private conservator in London she worked regularly for the Department of the Environment, the Royal College of Music, and private conservator Patrick Lindsay. From 1974 to 1976 she was assistant painting conservator at the Winterthur Museum, Delaware. She has been a conservator at the Fogg Art Museum since 1977. Address: Fogg Art Museum, Harvard University, Cambridge, Mass. 02138.

GIANFRANCO POCOBENE received his master of arts in conservation from the Art Conservation Program, Queen's University, in 1984. He was assistant conservator at the Art Conservation Laboratory in Raymond, New Hampshire, from 1984 to 1985. He returned to Queen's to conserve paintings from the university collection from 1985 to 1988. During that time he also worked on paintings from the Alfred Bader Collection and on several mural projects in Canada. From 1988 to 1989 he was a paintings conservation intern at the Center for Conservation, Fogg Art Museum. Upon completion of his internship he became assistant paintings conservator. He is currently associate conservator of paintings at the Straus Center for Conservation, Harvard University Art Museums. Address: Straus Center for Conservation, Harvard University Art Museums, 32 Quincy St., Cambridge, Mass. 02138.

Section Index

Copyright © 1997 American Institute for Conservation of Historic and Artistic Works