SHORT COMMUNICATION SOLVENT SENSITIVITY TESTING OF OBJECTS FOR TREATMENT IN A VAPOR-SATURATED ATMOSPHERE
ERIC F. HANSEN, & PAULA VOLENT
ABSTRACT—The authors discuss certain limitations to the technique of consolidating porous paint in a vapor-saturated environment described by Hansen et al. in earlier articles. The treatment of a severely flaking gouache on paper by Karel Appel is described, including various tests carried out using the chosen consolidant, a solution of poly(vinyl acetate) AYAF in ethanol, both in and out of the vapor-saturated environment. The final tests failed to provide the desired effect, resulting in some discoloration and staining of the treated areas. The artist himself later was consulted and indicated that his technique had helped create the problems in the consolidation process. In conclusion, the authors point out that it is extremely important to test the consolidant carefully with increasing exposure to solvent vapor before using it on an actual object.
In an application of techniques for consolidation of porous paint in a vapor-saturated atmosphere, as described by Hansen et al. (1993), certain practical limitations were discovered that should be addressed before using this type of treatment in the conservation laboratory. The limitations involved the possibility of increased solvent sensitivity of materials due to the prolonged solvent exposure necessary in the use of a solvent vapor chamber.
The vapor-saturated atmosphere was considered in the preliminary treatment design of the consolidation of a severely flaking gouache on paper, Untitled Figure 1953, by Karel Appel. Traditional techniques for consolidation of the gouache, including the use of a dilute gelatin or cellulose ether solution, proved extremely time intensive and also resulted in discrete changes in appearance. Lowinger (1993) had successfully used a vapor-saturated chamber to consolidate extensively flaking porous paint on wooden objects in a labor-saving manner. She introduced the resin by brush in a vapor-saturated atmosphere. The resin penetrated the porous paint in large areas without discoloration, and the flaking paint saturated by resin solution was laid down by applying a hot spatula to Teflon sheeting laid on the surface. This approach was considered for the gouache not only to reduce changes in appearance but also to reduce the time involved in the meticulous adhering of small, friable paint flakes over large areas.
After careful solubility tests on the Appel gouache, a solution of poly(vinyl acetate) (PVAC) AYAF in ethanol was chosen as a possible consolidant. PVAC is an extremely stable resin with excellent characteristics as an adhesive or a consolidant. Tests with the resin in other solvents, both toluene and acetone, caused various colored staining to develop in the area of application. Outside the vapor atmosphere the ethanol solution caused no stain formation, apparently because the consolidant had not sufficiently penetrated the porous paint layer. This insufficuent penetration resulted in both inadequate consolidation and a slight change in the appearance of the treated area; bright, white matte paint became grayish, darker, and slightly glossier. In order to achieve maximum penetration and distribution of the consolidant, thus preserving the matte quality, the consolidant solution was tested in the vapor atmosphere.
The drawing was placed in a glove bag along with open pools of ethanol, which saturated the atmosphere with solvent vapor. A small amount of the consolidant was applied to several test areas of the paint. When the drawing was removed from the bag, discoloration and staining of the areas tested were observed, similar to the staining observed when aqueous and organic solvent solutions were applied in an open atmosphere. This method was then rejected, and the flakes were laid down individually with a very viscous methyl cellulose solution. Methyl cellulose has also been evaluated as a resin sufficiently stable for use in the conservation of works of art (Feller and Wilt 1990).
In a subsequent interview, Appel disclosed that he often included colored magazine-page collage pieces beneath the drawing surface. This information suggests that the staining was caused by transfer of components of the colorants present in the magazine illustrations into the overlying colorant layer of the drawing. The colorants were slowly solubilized by the ethanol during the ethanol vapor-saturated treatment. Such solubilization and staining did not have time to occur when ethanol was applied to the drawing outside the vapor chamber.
Thus, solvent interaction tests must be done under the conditions in which they will be used. Careful testing should be done with increased exposure to the solvent before using any solvent atmosphere, including pretreatment of tape and adhesive staining with solvent cups or poultices, and in new applications of solvent vapor through permeable materials such as Gore-tex.
Feller, R., and M.Wilt. 1990. Evaluation of cellulose ethers for conservation. Los Angeles: Getty Conservation Institute.
Hansen, E. F., R.Lowinger, and E.Sadoff. 1993. Consolidation of porous paint in a vapor-saturated atmosphere: A technique for minimizing changes in the appearance of powdering, matte paint. Journal of the American Institute for Conservation32:1–14.
Lowinger, R.1993. Personal communication. Sculpture Conservation Studio, 1144 S. Stanley Ave., Los Angeles, Calif. 90019.
ERIC F. HANSEN received his M.S. in organic synthesis from the University of California, Irvine and is a C. Phil. in the Archaeology Studies Program of the University of California, Los Angeles. He is currently an associate scientist at the Getty Conservation Institute, where he has been employed since 1985. His research interests include the consolidation of fragile painted objects, the deterioration of organic materials (including both synthetic and natural substances), the effects of treatment parameters on the final physical properties of treated objects, and the technological styles used in the production of architectural sculpture of the ancient Maya. Address: Getty Conservation Institute, 4503 Glencoe Ave., Marina del Rey, Calif. 90292.
PAULA VOLENT received her M.A. in art history and her certificate in conservation from the Institute of Fine Arts, New York University. Pre- and post-conservation training internships include work in the paper conservation laboratories at the Northeast Document Conservation Center, the Williamstown Regional Conservation Laboratory, the New-York Historical Society, the Fine Arts Museums of San Francisco, and the Los Angeles County Museum of Art. She ran a private paper conservation studio in Los Angeles from 1990 to 1994. She is currently the William R. Leisher Memorial Fellow in the Conservation and Research of Modern Paintings at the National Gallery of Art, Washington, D.C.