Volume 10, Number 3, Sept 1988, pp.6-8
In 1972, as part of the New Talent Awards program, the Los Angeles County Museum of Art acquired an oversize drawing by the artist Ann McCoy. The drawing, entitled Mount Maurice, measures 9' 9-3/8" X 5' 3/16" and is executed in Prismacolor pencil on gesso prepared photographic backdrop paper. The artist had designed a method of exhibition similar to traditional techniques used in the installation of Oriental scroll paintings, utilizing a wooden dowel which was inserted through a sleeve formed by the folding over of the top edge of the drawing. In exhibition, the drawing was hung, unglazed, from the dowel. When not on exhibition, the drawing was rolled, face out on a large Sonotube.
In 1986, in preparation for the opening of the Anderson Wing of the museum, the curatorial staff suggested that the drawing might be exhibited as part of a series of rotating exhibitions showing the variety and diversity of contemporary artists represented in the permanent collections of the museum. On routine conservation inspection of the drawing, prior to approval for exhibition, the drawing was found to have developed structural weaknesses and damages in the area of the folded sleeve, endangering installation using the artist's original method of hanging. In addition, masking tapes which had been applied by the artist to secure the folded sleeve and as a method of reinforcing the edges of the drawing were in various stages of deterioration, with resultant loss of adhesion and the development of staining. At this time the paper conservation staff decided to implement a comprehensive conservation treatment for the McCoy drawing. The treatment would involve consolidation of damaged areas of gesso and paper which had resulted from handling and rolling; removal of deteriorated and aged adhesive tapes which had been originally applied by the artist and redesign and modification of the artist's original technique of installation for the greater safety of the drawing during exhibition.
The first phase of the conservation treatment was the establishment of a dialogue with the artist. This dialogue provided important information concerning materials and techniques used in the fabrication of the drawing as well as the artist's aesthetic concerns in the redesign or modification of the method of exhibition.
Due to the large size of the drawing and the artist's use of nontraditional media and techniques, it was often necessary, during treatment, to adapt and modify standard procedures in paper and paintings conservation specifically for the oversized drawing. The Prismacolor pencil was friable and somewhat sensitive to some solvents traditionally used in the removal of adhesive staining and adhesive residues. The poor-quality paper support had been prepared by the artist with the application of a smooth, chalky layer of acrylic gesso to the front and back. This surface proved very resistant to adhesives used for repair and for the attachment of any auxiliary support necessary for the modification of the original method of installation.
Masking tapes were removed from the reverse with a combination of mechanical action and local application of heat, directed from a hand-held heat gun. Adhesive residues remaining on the gesso surface were softened by heptane application and then removed with a microspatula. Tears and breaks in the support at edges and along the folded sleeve of the drawing were aligned and repaired with Japanese tissue and wheat starch paste followed by reinforcement with acrylic gesso.
The artist considered the free-flowing, scroll-like presentation of the drawing used in the initial installation as integral to her concept of the piece. However, the failure and fragility of the original folded sleeve at the top necessitated the rethinking and redesign of the method of installation. Due to its large size, and the multiple coats of acrylic gesso, the drawing is quite heavy, requiring some type of secondary support which would reinforce and evenly distribute the weight of the drawing during exhibition. Although overall lining was initially considered, with the exception of the area of the folded sleeve at the top of the drawing, the paper support was still structurally sound and did not warrant the risks involved in the application of an overall adhesive and lining layer. In addition, lining would obscure the artist's signature and inscriptions on the reverse. After consideration of a number of options, a treatment proposal was designed in which fabric strips would be attached to the top and bottom edges of the drawing. These strips would be used for the fabrication of two fabric sleeves. The new sleeve at the top of the drawing would reinforce the artist's original sleeve formed by the folding over of the drawing support. The addition of the second sleeve at the bottom of the drawing would add support to the drawing during exhibition by providing a method for the attachment of the bottom edge to the gallery wall.
After a method of exhibition preparation was agreed upon, it was necessary to select an appropriate adhesive and fabric for the attachment of the auxiliary fabric sleeves. The selection of an appropriate adhesive was particularly problematic due to the physical characteristics of the smooth gesso layer and to the extreme weight of the drawing. In addition to a great resistance to most types of adhesive bonding, the gesso layer was extremely reactive to moisture, prohibiting the use of water-based adhesives traditionally used in paper conservation. The gesso prepared paper also appeared to readily absorb any discoloration resulting from adhesive deterioration, especially evident in examination of a similar work by McCoy in the collection of the Allen Memorial Art Museum in Oberlin Ohio (Mount Everest, 1973.) In this drawing, dating from the same period as the drawing in the L.A. County Museum Collection, staining from masking tapes applied to the reverse by the artist appears in the drawing design. Close inspection of these areas suggests that the staining may have been wicked to the front by the multiple layers of gesso. Thus, a number of physical and chemical requirements were critical in the selection of the adhesive which would be used for the attachment of auxiliary strips to the McCoy drawing: the adhesive should form a strong adhesive bond between the fabric and the gesso prepared paper without causing delamination between the gesso and paper layers; the adhesive should have optimal qualities of peel strength in order to withstand the considerable weight of the oversized drawing; the application of the adhesive should not result in cockling or damage to the prepared surface of the drawing; and, on aging, the adhesive should maintain a neutral pH range, resist discoloration and remain reversible using techniques not harmful to the artwork.
The choice and use of an appropriate adhesive for the application to works such as the McCoy drawing often presents a serious dilemma to the practicing conservator. Although considerable information, both practical and scientific, is available on traditional adhesives used in conservation (eg. wheat starch paste), these adhesives are often not suited to applications to works of art where non-traditional media, technique or format is involved. Conservators faced with a nontraditional treatment often rely on a number of sources for the ultimate selection or rejection of a specific adhesive for application to a treatment procedure. In addition to practical experience with a particular material, (both in the laboratory and shared with colleagues) and chemical and physical data available through conservation research, many conservators carry out their own physical testing, sometimes quite primitive, within the confines of the conservation studio. These preliminary tests can provide some rough information which can be used to rank a series of materials, ultimately facilitating the conservator's final treatment design. A common type of practical testing is the use of mock-ups where a specific material under consideration for a treatment procedure is applied to a reproduction of the artwork. Problems or adaptations in application can be experimented with and adjusted without damage to the actual work of art. Often these mock-ups are also subjected to extreme environmental conditions in the laboratory to assist in the prediction of poor aging characteristics.
In the McCoy project, nine different adhesives in current use in applications to paper and paintings conservation were used for the attachment of fabric strips to mock-ups reproducing the structure of the drawing. In addition to recording properties of application and peel strength, each adhesive system was subjected to artificial aging in a 100° C dry oven for a period of four days. After thermal aging, peel tests were repeated and determination of discoloration and changes in pH and reversibility were carried out. The adhesives tested included wheat starch paste (Zin Shofu), vinyl copolymer-ethylene vinyl acetate adhesives (Beva Film, Flocked Beva), acrylic emulsions (Liquitex Acrylic Gel Medium, Liquitex Acrylic Gesso, Lascaux 360HV, Rhoplex AC33, Rhoplex N580), and poly vinyl acetate emulsions (Jade 403).
After evaluation of test results, an acrylic resin adhesive, Rhoplex AC 33, applied as a heat set adhesive, was selected for the attachment of the fabric strips to the McCoy drawing. Plain weave filament polyester fabric strips were prepared by brushing with several coats of the acrylic resin emulsion. After drying, the strips were aligned over the edge of the drawing and attached with a tacking iron set to approximately 145°. F. Adhesion was adequate for the fabrication of the sleeves, although the attachment could be reversed with mechanical action and peeling. In testing, the acrylic resin emulsion showed optimal characteristics of aging, strength, and reversibility. Due to problems with cockling in the drawing on application of the wet emulsion, experiments with the adhesive as a heat set type of adhesive were undertaken. These tests showed good qualities of aging and strength without the problems associated with moisture content. The heat set adhesive could be readily reversed with mechanical action or exposure to heat or solvents and had adequate strength properties to support the drawing during exhibition. The fabric strips were folded over and joined at the edges with BEVA film (a vinyl copolymer-ethylene vinyl acetate heat set adhesive) to form the fabric sleeves. Two 1-1/2" stainless steel bars, sanded and sealed, were selected for insertion in the new fabric sleeves during installation, replacing the artist's original wooden dowel. A solid mount, fabricated with Gatorfome and matboard attached to a wooden strainer, was designed for the support of the drawing in storage.
A review and evaluation of the testing and conservation treatment program for the McCoy drawing at the Los Angeles County Museum reveals a number of issues which are of critical concern to conservators involved in the conservation of contemporary works of art. The involvement of the artist in the preliminary treatment design facilitated the project through identification of actual materials used and aesthetic concerns in presentation. However, in initial conversations, she expressed her preference that the museum replace this early work with a more recent work, in an entirely different style. Although this opinion was later changed as the treatment progressed, the artist's dissatisfaction with this early period of her work may have had serious results had the artist been entrusted with the repair and consolidation of her own work.
In the conservation treatment of such a nontraditional drawing, it is necessary to continually adapt and modify traditional techniques and materials. Materials used in treatment may be relatively recent additions to the conservation field, or in some cases borrowed from the artist's studio or from industrial use. Although adhesives such as starch pastes and cellulose ethers are the principal adhesives used for the repair and preparation of works of art on paper, with well-documented information on characteristics of aging and use, in the case of the McCoy drawing, such adhesives were ineffectual and inappropriate. Synthetic adhesives, including acrylic emulsions, ethylene vinyl acetate mixtures and poly (vinyl acetates) appeared to have greater potential for application to the McCoy conservation treatment. However, the selection of the appropriate adhesive was complicated by a lack of accurate scientific and practical information concerning the application of such adhesives to works of art on paper as well as any data on their long-range aging characteristics when used on a composite paper support. In the McCoy treatment, adhesives which had potential for use in treatment were tested by oven aging, according to common paper conservation procedures1 . Some adhesives such as the ethylene vinyl acetate mixtures performed poorly under these thermal aging conditions, with the development of considerable discoloration of the adhesive layer as well as staining and penetration of the underlying composite paper support. However, a careful examination of test results as well as consideration of the chemical structure of each adhesive, suggests that the aging conditions used in these experiments may have been excessive and inappropriate for synthetic materials with low glass transition temperatures or poor resistance to such low levels of humidity. Thus, it seems that artificial aging conditions used for the determination of permanence and durability in traditional paper conservation may be inappropriate and inapplicable for the determination of the physical characteristics of synthetic materials adapted for use in paper conservation.
As a result of the data obtained during the course of the McCoy project, a concentrated research project concerned with the artificial aging of a number of adhesives used in applications in paper conservation has been undertaken. In this research, samples will be subjected to a variety of thermal aging conditions with differing levels of relative humidity and temperature. The aim of the research is twofold. First, to assist conservators and artists in the selection of an adhesive for a specific application; secondly to assess the validity of thermal aging in paper conservation, especially in testing of new synthetic materials where chemical reactions on aging may be very different than in materials from traditional natural sources.
This project would not have been possible without the assistance of many people: especially the staff of the curatorial and conservation departments at the Los Angeles County Museum of Art, in particular, Victoria Blyth-Hill; the artist, Ann McCoy; and for editorial insights, Mark Watters and Denise Domergue.Paula Volent, Research Intern, Conservation,
1. 100°. C oven aging, in a dry oven, is standard in conservation literature directed towards applications in paper conservation. See, for instance, William K. Wilson and E. J. Parks, "Comparison of Accelerated Aging..." Restaurator 4:1, No. 1, 1980. See also N.S. Baer and N. Indictor, "An Examination of Test Methods for the Evaluation of Papers and Paper Conservation Materials", Archives et Bibliotheques de Belgique 12: 1974.