Old Master Drawings: An Approach to Conservation

The expression "old master drawing", which today is used rather reluctantly, can probably be traced back to the late sixteenth and seventeenth centuries when works of such highly esteemed Renaissance artists as Raphael, Correggio and Tintoretto were first being collected. Their drawings are recorded as having been in the Kunstkammern of royalty, including Lorenzo de Medici, the fabulous holdings of wealthy merchants including Andrea Vendramin, and not least in the collections of artists, that of Rembrandt perhaps being the best known. Drawings of the old masters were not only admired for their beauty, but also serving as teaching tools in the atelier, providing a means for studying the methods and style of the draftsmen who had changed the course of art. The sixteenth and seventeenth centuries were also a period when biographies of the great Renaissance artists were being written, such as those by Vasari, Baldinucci and Van Mander, which not only popularized the old masters, but established these laudables as the cornerstone of academic art. In the eighteenth century recognition of their work was brought to a far wider audience with the development of new printing processes, such as engraving in the crayon and stipple manner and mezzotint printing, further impressing their particular place in the history of art.

Today the greatness of the work of these artists of past centuries remains undiminished, however, the term master drawing is preferred. Drawings from the fifteenth, sixteenth, seventeenth, eighteenth and nineteenth centuries are from our present vantage point all old, and establishing a chronological dividing line between the old and the modern becomes an increasingly complex task. Nonetheless, issues of chronology and terminology aside, there are rather significant differences between the materials, techniques and therefore the conservation of drawings of the late nineteenth and the twentieth century and those of the preceding four hundred years. Sharp dividing lines are impossible to establish for materials. Even those considered to be obsolete by a certain time will occasionally be found at a much later date (iron gall, lead white, ceruse, etc). Of the earlier periods, perhaps through the eighteenth century, the range of materials, designated by traditional workshop practice such as recorded by Cenino Cennini, was less extensive than that presently encountered. The most commonplace mediums were natural red, black and white chalks and charcoal, all of which have remained in use today, although in modified compressed and artificial forms. Also common then were black inks, bistre, watercolor washes and a thick, water soluble gouache or body color and tempera. Other materials which were used but are now either rare or obsolete are oiled charcoal, lead white metalpoint, and iron gall ink. Iron gall ink which remained popular until the late nineteenth century, has no parallels in terms of its components or conservation problems in the present time. As for supports, in addition to parchment and vellum, before the nineteenth century the only paper available was hand made rag fiber. By the seventeenth century Oriental papers were used, such as those found in drawings by Rembrandt. Early papers are longer fibered than machine made papers which were introduced in the nineteenth century. They were not chemically bleached, contained few impurities and metal particles, particularly before the Hollander beater, and were only available in a limited color range—shades of white, cream and indigo, although sheets toned by the artist with body color or colored washes were also used to provide a background hue for ink and chalk drawings, as well as for early pastel studies. These papers, and hence the drawings, tend to be of small scale, the exception being sheets joined together for cartoons for tapestries or for wallpaper.

Many of the procedures used for modern works on paper are employed for conserving early master drawings at the Metropolitan Museum of Art, however, the range of treatments is more limited for the latter group. For example, buffering, lining and immersion bleaching are rarely undertaken with this group. In place of buffering the inherent good quality of the paper is relied upon. Instead of adding any chemical to the paper, the degradation processes is slowed down by using acid-free mounting materials, and by controlling the temperature, relative humidity and air quality of storage and display areas. Unlike books, these works are never handled and they are housed either in solander boxes or in the protective setting of their frame. Lining is carried out infrequently because the strength of these sheets generally does not require it, nor is it found to be aesthetically pleasing to the topography of the paper. It is also preferred to have the verso visible in order to be able to study watermarks, inscriptions or aspects of the medium or pigment such as penetration and color characteristics (for example, of copper acetate and iron gall ink), none of which would be possible if the sheet were lined. Immersion bleaching with any type of bleach is not done because it is generally not required. The papers are of good quality and have few impurities and fillers, and there are few instances of pronounced discoloration that demand bleaching. These works, as well, were rarely exposed to prolonged periods of sunlight which would have altered their natural color. Washing by immersion or on the vacuum table, however, is carried out when appropriate and if the support and medium can withstand this treatment, and preferably in alkaline water. Each of these rare and invaluable drawings is treated on an individual basis. The extent or limitations of treatment, however, not only depends upon the nature of the problems, the condition and stability of the design layer and the paper, but also on the history and use of the particular drawing. For the latter, it is important that the conservator consult with art historians or curators or undertakes independent research in order to compare the work in question with others by the same artist, or of the same era or provenance.

In this context, one of the most common issues that arises in conserving an old master drawing is backing removal; not simply how it is to be done, but whether or not it is to be done at all, and how this decision will bear on subsequent treatment or mounting that the work requires. Unlike many nineteenth and twentieth century mounts, which are almost invariably removed from a print or drawing because of poor quality adhesives and wood pulp materials and the problems of acid migration, the same criteria do not always apply to old master drawings. For this group the decisions are often more complex.

Backings on old master drawings are very common. Except for important portraits or presentation pieces, these works were not framed, but were glued or pasted into portfolios and albums or laid down to card or laminated sheets of paper. They were prepared this way by collectors and by artists so that they could be handled for study or for copying in the studio or academy. These early mounts generally were of the same quality of the work of art they supported even when they were not contemporaneous with it. They may contain information about the drawing's history, the collector, bear collector's stamps or record inventory or shelf marks. Some are elaborately decorated as the famous Vasari mounts, or those of Mariette with cartouches, gold fillets and tinted borders, or may have the simpler format of a particular collection such as that of Jonathan Richardson.

Often these mounts are intrinsic to the history and aesthetics of the object and hence the work of art and the surround must be regarded as a total entity. This must be borne in mind in making decisions as to the type of conservation the work requires: should the art work and the mount be separated for treatment, or kept intact and the piece conserved in situ. In many instances the condition of the object demands more than surface cleaning or localized repairs and fills, and hence the backing must be removed. If for example, waterstaining or foxing is deeply ingrained and so pervasive that it disrupts the reading of the art work, it can only be reduced or removed by separating the object from the mount so that cleaning can be undertaken from the recto and the verso. Another instance where the work would have to be separated is if there is buckling and air pockets which made the composition difficult to decipher. Also justifying separation of the work of art from the mount is if the backing and the adhesive layer are so dark that their removal would optically brighten the primary support. Whenever possible the mount or the framework of the mount should be preserved and the drawing hinged or inlaid onto it in a manner which simulates the original effect.

Despite the wisdom of removing backings in circumstances such as the above, there are other considerations that must be addressed in dealing with old master drawings. One of the first is the significance of the mount to the object's history. Evidence of provenance is extremely important for all drawings, but particularly for unsigned early works because it often supports attributions and authenticity. Secondly, if inscriptions are present, will they be destroyed by removing the backing? Photographic documentation is always important but it is far more significant to have the actual inscription preserved. A third consideration is determining the nature and extent of existing damage. For example, if there is no evidence of adhesive staining, or if the adhesive has not exerted tension on the support it often makes more sense to leave the mount intact and not sacrifice part of its history. A fourth factor is determining the risks to the work of art in undertaking a backing removal. For example, a red chalk drawing executed on a porous and absorbent sheet of paper—or one that has become so with the breakdown on its sizing, would be likely to be moisture stained in the course of removal from the mount owing to the migration of the discoloration products in the paper or the adhesive. The risk of chalk offsetting or inks bleeding also exists when moisture or humidification is required for a backing removal. Iron gall ink drawings are at particular risk when a backing is removed. Although they may appear to be in stable condition when firmly adhered to a secondary support, manipulation of the sheet, and the expansion and contraction of fibers in the presence of moisture vapor in the stronger reserve areas can promote fracturing of the severely embrittled ink covered sites. N-methyl-2pyrrolidone may avoid some of these problems for the conservator familiar with this solvent, but no matter what the method of back removal, an iron gall ink drawing will often require a lining or localized support following treatment. Moisture for applying this support can be as detrimental to the drawing as it was to the removal of the previous backing, and dry mounting tissue is not the most favorable solution. Another circumstance which argues in favor or preserving the mount, is in the case of parchment which has been laid down. Unless the object is severely distorted and can only be realized by separating it from its mount, the process of removal can encourage flaking of the paint layer. Once the backing is removed, the parchment is far more vulnerable to distortion and paint loss from fluctuations in relative humidity.

Related to the issue of preserving the original mount is that of old repairs. The restored corners on a portrait drawing for example, perhaps could be cosmetically restored, but will the new replacement significantly improve upon the old to justify the alteration, and do the old repairs refer in any meaningful way to the object's history. Another matter which falls closely on the heels of this is that of ancillary material adhered to the primary support. Do little tabs of paper, or cut out collector's stamps relate to the drawing's early history? Similarly, are the stains, corrections, scribbles or smudges part of the working process or simply the result of mishandling and neglect that occurred well after the work was executed? Questions such as these should be explored before embarking upon irreversible changes.

There is still another point that is often voiced in justifying a backing removal. Today, prevailing taste enjoys seeing the texture of a sheet of paper and the subtle undulations it makes in response to changes in atmosphere. However, the flatness of these laid down drawings should be respected. Those who mounted these works were perhaps closer to the aesthetics of the old masters than are we. This is similarly the case with pastels of the late seventeenth and the eighteenth centuries. Their original format, paper stretched over a wooden strainer, not only provided a resilient surface for the artist to work on but it gave the pastel the stature of an oil painting, the medium with which it was perennially in competition. The mounting tells something about how a drawing or pastel was used and displayed, and about its cultural context, and for this reason alone it should be preserved.