Volume 11, Number 1, Jan. 1989, pp.2-4
Rosamond Westmoreland - Conference Chair
Denise Domergue - Session Chair
Debra Evans - Session Chair
Mark Watters - Session Chair
Elisabeth Cornu - Session Chair
For the benefit of members who were not able to attend the WAAC Annual Meeting in Yosemite here follow abstracts of the presentations.
In his mural series, "The Role of Biochemistry in Plant and Animal Nutrition," located at the University of Wisconsin- Madison, John Steuart Curry utilized various paint media, including watercolors, oil paints, a tempera emulsion, and his version of the Maroger Medium, to create a technically complex structure. His technique and combined use of these materials is reviewed based upon technical information provided by one of Curry's studio assistants who worked on the project, as well as information gleaned during the examination and treatment of the mural paintings.
The paper discussed a survey project for 49 Chinese and 29 Luristan bronzes from a collection in Honolulu. The survey included the examination and evaluation of the stability of the bronzes, an evaluation of the storage and exhibit areas as well as treatment of six of the pieces. A computerized survey form was used to insure consistency and to aid in final condition prioritization of the pieces in order to provide the owner with a long term conservation plan. The number and variety of repairs found on the pieces was most notable. 3/4 of the Chinese and over half of the Luristan had been repaired previously. The point was made that even after thorough examination, repairs can go undetected. A more detailed report on the environmental survey will be written up by Dale Kronkright in a future Newsletter.
Problems with Plastic Paintings: discussion of various treatments of polyester and acrylic paintings and sculptures.
Chocolate has been worshiped by mankind ever since the first bitter cups of the aromatic liquid were sipped. This important material has been given its due by immortalization as art. A three fold presentation by Sharon Blank, Claire Dean, and Glenn Wharton covered the history of chocolate as an artist's material, the manufacture and deterioration of chocolate, and several case studies of chocolate conservation. The treatment of a chocolate artwork by Claes Oldenburg and the removal of chocolate stains were discussed. Samples of both English and American chocolates were available, allowing true chocoholics to remain conscious throughout the lecture.
Installation of the Price Collection of Japanese Art in the new Japanese Pavilion was discussed.
When comparing the extent of acidic reaction with water via the pH, wood is usually found in the middle to upper pH range of biological materials. Wood pH values have been reported between 3 and 8.5, slightly less acidic than apples and oranges, with most woods having a pH in the range of 4.5 to 5.5, comparable to white bread or cheese. Nearly all the volatile and soluble acidity in wood stems from acetic acid, which is generated by the hydrolysis of acetic acid esters with the hydroxyl groups of wood polymers. Common problems with wood reported in museum storage are related to the solubility of acetate salts (e.g. of calcium and lead), rather than acidity per se.
The conservation of silver was discussed, including a brief introduction on the proper handling and storage of silver artifacts. Glenn has recently completed a comparative study of abrasive systems for polishing silver at The Getty Conservation Institute. These findings were presented, along with practical advice on chemical cleaning and lacquering of silver.
Applying a polymeric film (coating or adhesive) by solvent evaporation (drying) of a solution can result in films of different properties depending upon the thermodynamic state of the polymer in solution. "Good" solvents extend the polymer chain in solution and "poor" solvents cause retraction. A larger conformation (hydrodynamic volume) promotes interchain interactions while a smaller conformation promotes intrachain interactions. These changes in polymer conformation persist in the film after solvent evaporation. Examples of this effect from the literature include ethyl-cellulose films and poly(vinylacetate) films. Experimental data was presented to show that this effect persists through time by testing films at intervals of 1.5 and 6 months after casting.
Films of poly(vinylacetate) (AYAT, AYAF and AYAA) were tested by tensile fracture for mechanical properties, gas chromatographic analysis for retained solvent, and thermal analysis for determining the glass transition temperature (Tg). Films from poor solvents (acetone, an acetone/ethanol/water mixture) resulted in higher glass transition temperatures and brittle, stronger films in comparison to films from good solvents (chloroform, toluene) with a resulting lower Tg and significantly greater elongation. Retained solvent was high (>7%) for films cast from toluene indicating that in this case the film was plasticized.
The effect of solvent is greatest for polar polymers and polar solvents, and thus is an important consideration for the field of conservation where acetates and acrylics are widely used as coatings, consolidants, and adhesives. Other properties affected are adhesion to a substrate, refractive index, hardness, and longevity (aging). Replacement of one solvent by another solvent based only upon workability of the solution or toxicity of the solvent may result in unexpected and undesirable physical properties.
GCI, in conjunction with CCI and CAL, is testing the effects of sulfuryl fluoride (Vikane TM) on materials found in museum artifacts. As part of this program, GCI developed two new methods to examine gas/solid interactions. This presentation described both methods and their applications in determining the effects Vikane has on materials, such as metals.
Thirty-six paintings of the Missions of California painted by Henry Chapman Ford between 1875 and 1881 provided an interesting case study involving the processes of relaxing cracking/cupping and deformations in paint through the use of humidity treatments. Although the paintings were painted within a relatively short period of time by the same artist, they exhibited extensively varying conditions due to storage and numerous previous restorations. The presentation centered on the relaxing of paint and ground films upon exposure to humidity, heat, and organic solvents. The subsequent linings were performed with PVA emulsions and stiff polyester fabric. The theories behind the treatment of exposing paintings to these conditions (heat, humidity, organic solvent vapors) can also be applied to the transfer process of paintings (extreme conditions).
The serious degradation of ten Chinese stone sculptures in the collection of the Seattle Art Museum and plans to move the sculptures indoors and replace two of them with replicas was discussed.
J. William Shank, Paintings Conservator at the San Francisco Museum of Modern Art, presented a paper on a recent conservation treatment of an oil-on-panel painting by American artist Maxfield Parrish. A brief history of Parrish's career and style was followed by a description of his unusual, fastidious technique: a variation of the four-color printing process, composed of multiple layers of transparent oil glazes, separated by natural resin varnish layers. A painting that had been heavily damaged by previous cleaning was treated by the conservator, with methods that included the use of spraying toned varnish to compensate for large areas of loss.
An Overview of Paper Conservation was presented.
A discussion of a collaborative conservation project involving paper, textile, painting, and objects conservators. The materials used by the artist were briefly described as were some of the conservation problems. An outline of the treatment chronology was also presented and the working relationship between conservators discussed.
Discussion of improved techniques used in the conservation of a variety of ethnographic materials.
Several examples of common conservation problems encountered while caring for the Getty's collection of old master drawings were discussed. Examples were shown of design realignments, darkened lead white reversals, and restoration of damage caused by iron gall ink, insects, and skinning. Reference also was made to the discovery of verso images. Storage and display conditions of the 250 drawings were described.
Arno Schniewind reported on the Archaeological Wood Symposium sponsored by the Division of Cellulose, Paper and Textiles of the American Chemical Society and held in Los Angeles September 26- 29. Dry Archaeological wood is remarkably stable; as can be buried, waterlogged wood under some conditions. Often bacterial degradation sets in, which makes unearthed artifacts very difficult to dry. Dr. Roger Rowell, chief organizer, presented some ideas on chemical modification of degraded wood for stabilization. The proceedings will be published by ACS in book form under the title "Archaeological Wood: Properties, Chemistry, and Preservation."
Several of the most important issues which must be faced by the conservator of plastic objects were illustrated. These include the identification of the plastic, the complexity of plastic formulations, chemical susceptibilities of plastics, and the choice of adhesives and inpainting media. These ideas were then discussed in connection with the conservation treatment of several plastic objects.