Volume 15, Number 1, Jan. 1993, pp.5-9
Volume 15, Number 1, Jan. 1993, pp.5-9
The 1992 WAAC Annual Meeting was held September 27-29 in Santa
Fe, New Mexico. The papers from the meeting are listed below, in
the order of presentation, along with summaries prepared by the
speakers.
Please Note: These symposium papers are being transcribed, and WAAC Newsletter expects to publish them in a forthcoming issue.
Himalayan art is still incompletely understood. Most thangkas are unsigned and undated, and their provenances are often unknown. In addition, thangkas also exhibit a variety of styles and an almost bewildering array of deities, all of which can make the study of these works difficult. Examination of some major paintings in the Los Angeles County Museum of Art collection has clarified certain questions, and it is hoped that an even fuller understanding of both the art historical and cultural contexts of this art tradition will emerge with further research.
The talk was assisted by slides and demonstrated the techniques and processes used to produce traditional paintings, thangkas, and paubhas by Newar and Tibetan artists in present-day Nepal. The process was described step by step, and the materials were described in detail.
Western appreciation of the artistic achievements of Himalayan art is a relatively new phenomenon. Collecting Himalayan paintings in the last few decades has been an interesting enterprise as this was when the art first garnered much public attention and when many new works appeared. Making acquisitions in this area involves consideration of various factors; of especial importance are not only the consideration of the aesthetic and historical aspects of the paintings but also decisions concerning their condition and manner of presentation.
For over 8 centuries, Himalayan thangkas (paintings on cloth) have been created by Buddhists as an expression of their religious beliefs. Less than 100 years ago, these paintings (which were originally mounted with cloth or embroidered borders) became part of Western art collections. It is only recently that conservators and historians have begun to evaluate the way these mixed media paintings are displayed and stored in relation to their original intent. This presentation reviewed the evolution of conservation, display, and storage techniques in the treatment of Tibetan and Nepalese thangkas using examples from the collection of LACMA, and other collections throughout the world.
The Los Angeles County Museum of Art sponsored an IMS Fellowship in 1990-91 to thoroughly examine, photograph, document, and prioritize treatments for each of the 75 Tibetan thangkas in the Museum's collection. During the survey, we grew into a center for research on Tibetan art, making research accessible on LACMA's mainframe computer database, initiating correspondence with Himalayan art specialists, and traveling widely to study Tibetan collections. These exchanges expanded our research capabilities for information on conservation, exhibition, authentication, and the philosophical issues regarding the treatment of sacred objects.
The conservation of this thangka in LACMA's collection was a collaborative process involving paper, textile, object and painting conservators and discussions with several curators of Indian and Himalayan art. The condition of the thangka prior to conservation treatment was illustrated, revealing problems resulting from soot, yak butter lamps, extreme environmental problems and the application of modern synthetic wax. Solutions for treatment and display were presented.
Several problems associated with the use of Kodak Rapid Selenium Toner were encountered during a major negative duplication project at the San Diego Historical Society Photograph Collection. Problems included increased gamma, split- toning, and lack of an in-house method for quantifying toning protection for treated negatives.
A polysulfide toning treatment developed by the Image Permanence Institute (IPI), Rochester, NY, was implemented to replace the previous selenium treatment. The treatment addressed the major problems experienced with the selenium toner while presenting relatively few new difficulties.
Implementation of the IPI polysulfide toning treatment using a large tank system and Kodak Professional Direct Duplicating Film SO-339 was presented. Descriptions of testing, problem solving, and final treatment procedures were reported along with a comparison of polysulfide treatment on several other films.
In this presentation, we discussed the importance of acidity in the conservation of cellulosic materials (particularly paper). We reviewed the appropriateness and applicability of pH measurement in conservation practice from a practical and theoretical point of view. The focus was on the assumptions underlying the use of pH measurements as a basis for treatment decisions, and on our motivation for attempting to develop and alternative method of acidity measurement.
An evaluation was made of the moisture-buffering capability of four types of museum cases (Solander box, portfolio box, document box, and music box) against high, as well as low, environmental relative humidity. The results were expressed as hygrometric half-lives. The effect of size, material characteristics, and closure characteristics also was presented. (from the speaker's abstract)
Ageless (TM) is an oxygen scavenger used to produce and maintain low oxygen atmospheres. This paper presented the results of an extensive study on the rate at which Ageless absorbs oxygen.
The findings of this study will be reported more fully in an upcoming WAAC Newsletter, as well as in an extensive article in Studies in Conservation.
Documentation of historical musical instruments is a very important task before any restoration and conservation treatment, not only for detailed studies of a maker's technique, but also to clarify "authentic" construction practice before accurate modern copies can be made.
In recent years, the use of radiography and remote visual inspection systems (borescope) have proven to be effective tools for the examination and documentation of construction techniques of 17th- and 18th-century stringed instruments. Presented in this talk were methods used in the analysis of particular instruments from the Erich Lachmann Collection of Historical Stringed Musical Instruments; knowledge gained from this ongoing study should add to a growing body of information that will clarify our understanding of early music and performance through documentation of instrument design and proportion. It was recommended that more institutions and individuals identify and document authentic construction practice in historical stringed musical instruments.
In 1965, the Field Museum opened a new exhibit of its unique collection of Tibetan artifacts. Thirty years later, it was brought to the attention of the Division of Conservation that "mold" was growing all over the metal objects in the exhibit. In following up these reports, it was found that almost all of the copper, brass, and silver objects (approximately 600 items) in the exhibit were covered with a lush growth of sulfide crystals.
This paper discussed the steps taken to identify the source of the sulfur (the carpet in the case). How the problem was rectified was outlined. The conservation treatment undertaken was discussed. The degree of damage sustained by the objects was described and illustrated.
The case history described in this presentation provides a dramatic example of why our concern about the use of inert materials to construct and furnish exhibit cases is well placed.
Into the life of every conservator comes a collection move. This inspiring tale focused on the efforts of one conservator to plan and direct the evacuation of a warehouse full of historic artifacts. The audience was invited to: Thrill to the details of packing and inventorying tens of thousands of objects! Triumph as our heroine overcomes logistical and administrative obstacles! Chills will run up your spine as you discover ways to keep a move crew motivated! All this and more to prepare you for moving collections, a real life adventure.
This presentation reported the findings of a survey conducted while the speaker was Conservator for the National Museum of the U.S. Army. Automated retrieval systems are currently used for a variety of tasks such as: moving fragile produce in large warehouses, video retrieval, and storing and retrieving electronic parts in a huge warehouse/factory that assembles bombs.
The U.S. Army, Center of Military History, Museum Division, is currently investigating installing an automated retrieval system in a state-of-the-art historic artifact storage facility in Anniston, Alabama.
Marouflage was a very common technique for installing paintings in architectural settings in the 18th and 19th centuries. It can also be a valuable preventive-conservation method to mount murals which will have to be relocated in the future.
An 8.5 ft. x 50 ft. mural, painted on canvas by Judith Baca, was recently installed to flush-fit the reception area of the new Southern California Gas tower in Los Angeles. The painting, previously prepared with BEVA 371, was unrolled vertically onto the wall, which was progressively coated with BEVA gel. This contact system enabled the conservators to work in cramped quarters with minimal exposure to solvents. In addition, control over the degree of bonding will allow for relatively routine removal in the future.
This paper described and illustrated some of the difficulties and opportunities presented by using the Beva system as a contact adhesive for mounting of large works.
Terri Schindel gave a brief history of the initial circumstances surrounding the discovery of the suit in 1966 and a summary of the elaborate treatment needed to conserve it at Hampton Court, England.
Sharon Shore described the current condition of the suit and the process of designing and fabricating an internal support system suitable for long-term exhibition. In particular, the presentation discussed the necessity for coordinated efforts by many staff persons at the Museum of International Folk Art to safely achieve the completion of the project.
This paper reported the conservation treatment and historical background of a "slat painting" belonging to the National Museum of American Art in Washington, DC. A slat painting, also known as a "three-in-one" or "three-way" painting, consists of a background image on a flat ground which is partially obscured by a series of perpendicularly projecting slats. Images are painted on both sides of the slats so that different pictures are perceived from the left angle, center, and right angle, as the viewer moves across the face of the work.
Treatment consisted of paint consolidation, surface cleaning, removal of varnish with resin soap, mending of tears with polyamide powder, fabric inserts, reinforcement of turnover edges with hollytex, inpainting, and minor modification of the original frame.
What is most interesting about the piece is its unattributed provenance and the relationship between the three men portrayed: presidents Thomas Jefferson and James Monroe, and a third person who may be the Creek Indian chief Mackintosh, who was deeply implicated in political issues of his day.
Please Note: These panel presentations are more fully reported in in an article titled, "Cultural Aesthetics and Conservation in New Mexico," in this issue of WAAC Newsletter
Claire Munzenrider, Chief Conservator, Museum of New Mexico, presented attitudes and practices of restoration of Spanish Colonial altarscreens found in active churches in northern New Mexico. The care and repair of these churches traditionally lie with the community. Observations and participation in the restoration process was presented.
Keith Bakker, Intern, Museum of New Mexico, discussed the visual condition of Spanish Colonial furniture in northern New Mexico in relation to the prevailing cultural aesthetic of New Spain during the 17th century. Comparisons were made to the ever-popular Santa Fe style of interior decoration. The intention was to promote discussion of possible surface treatments in the conservation of Southwestern furniture.
Landis Smith, in private practice and a Contract Conservator with the Museum of New Mexico, discussed the complexities of accurately reading and conserving historic Southwest Indian pottery for an exhibit. It has been observed that past treatments have often imposed an historically inaccurate aesthetic on these objects. With the goal of maintaining both the historic and aesthetic integrity of the pottery, treatment decisions consider as much cultural, historic, and technological information as possible.
Bettina Raphael, Senior Objects Conservator, Museum of New Mexico, discussed conservation for an exhibit of Southwestern silver and the impact that Native American aesthetics as well as technology/history of use can have on treatment decisions. Collaborative work with Native Americans, curators, silversmiths and other conservators was presented.
(summaries based on the speakers' abstracts)Richard Wolbers began his talk with a bottle of Pert Plus shampoo on the podium and the adages "Start with the ideal and work backward" and "Start with the real and see if you can improve on it."
Wolbers's topic was his method for building cleaning systems around water; cleaning systems to remove specific accretions from the surfaces of art objects in a precise and closely-controlled way.
Developing a cleaning system begins after identifying the soil to be removed and the "environment" of that soil--that is, the kinds of substances from which the artifact or art object is made. This identification can be made based on analyses such as microscopic examination of cross sections. It can also be made on the basis of conventional testing and examination, or on a known history of the coating.
If investigation reveals that no water can be tolerated by the art object, aqueous cleaning systems obviously must not be considered further. If water can be tolerated, then the development of a custom aqueous cleaning system can proceed.
In the world of chemistry for commercial products, there are a great many components that are used to make up water-based cleaners. The chemists who develop these products systematically combine substances that offer particular features for a user: that's the significance of the Pert Plus shampoo on Wolbers's podium. Pert Plus contains about a dozen components selected to modify the basic cleaning capability of water. Wolbers teaches that we can use the same approach to designing cleaning systems for art surfaces.
The "shopping list" of ingredients that can be considered for inclusion in a cleaning system is very large. Wolbers noted, for instance, that there are about 30,000 surfactants listed in a current tradename directory of surfactants (and although some structures are identical, the range of choices remains huge). And surfactants are just one category of ingredients that can be considered for inclusion in a cleaning system. Others noted in this presentation were pH buffers, agents to control ionic strength, chelation agents, reagents, corrosion controllers, thickeners and absorbents, preservatives, solvents, and other ingredients, including enzymes. Understanding the roles of possible cleaning-system ingredients and their effects on art materials is not simple. Wolbers explained the basics for making some of these selections.
There are systems to help in decision making. The HLB system (hydrophile/lipophile balance number) provides a scale to assist in evaluating detergency of different surfactants. Wolbers explained that a surfactant's CMC (critical micelle concentration) is the amount of detergent which will just begin to do the job, so two to three times the CMC is all that is ever needed in a cleaning system. He explained how CMC and HLB together are related to the clearance of a detergent from a surface. Wolbers also discussed strategies to remove the residues of these customized cleaners, and how the design of the cleaning system can take into consideration the art object's tolerance for various kinds of "clearing" of cleaning-system residues.
Wolbers seeks to expand the possibilities for cleaning art surfaces by employing the method used by industrial chemists who develop specialized cleaning products that perform within closely-defined parameters. Using the same approach, a logical step-wise sequence is followed in tailoring water-based cleaning systems for particular cleaning problems on art. Custom cleaning systems designed in this way have proved to effectively clean unwanted components from painting surfaces while leaving adjacent coatings and paint unaffected.
Solvent gels have been used for the removal of pressure sensitive tapes and the staining caused by them. The most common tapes encountered have been those with cellulose acetate or paper carrier and poly acrylate adhesives, and the framer's tape Filmoplast P90 (paper carrier and 2-ethylhexyl acrylate adhesive). The gel used to soften the adhesive enough to lift off with a microspatula is: 300 ml acetone, 20 ml Ethomeen C25, 6 g Carbopol 954, 50 ml water.
For tapes that may date prior to 1960 the adhesives can be rubber-based or terpene- and petroleum-based with mineral oil or lanolin plasticizers. This includes drafting or masking tape and black photographer's tape. In general, a xylene gel will work better for these tapes. The basic formula used is: 200 ml ethanol, 50 ml xylene, 10 ml Ethomeen C25, 6 g Carbopol 954, 50 ml water. However, in cases where the tape has had exposure to extreme conditions, the more polar acetone gel may give better results.
For removal of white glues such as Elmer's, Weldbond, and Titebond that have polyvinyl acetate adhesives with various additives, an acetone gel has been found to swell the hardened adhesive to the point that it can be picked up with a microspatula.
General application: the gel is not used directly on the paper support of the art, but is spread onto a piece of Japanese paper, rayon paper, or thin Hollytex to be used as a poultice. This is important because the gel would be very difficult to remove from the interstices of the paper fibers. The poultice is covered with mylar film and may have some light weight added to provide adequate contact with the surface of the tape or tape stain. Exposure times as short as 30 seconds and as long as 10 minutes have been needed to soften or swell a crust of adhesive, or to begin the movement of staining material into the gel. Some additional work using a vacuum suction table to flush solvent through the affected area may be needed. I have found that acetone after the use of acetone gel, or xylene after using xylene gel, works well. More toxic solvents or solvent mixtures are not needed.
Numerous works on paper rescued from a home damaged in the Oakland-Berkeley Hills fire had deposits of soot and grime. These deposits had become stubbornly ingrained from being soaked with water from the fire hoses. Extensive surface cleaning with dry eraser techniques and subsequent bathing did little to move these deposits. A mixture of 100 ml water, 0.05 ml Triton X-100, 1 ml triethannolamine (pH adjusted to 8.5 with HCl), 1 g EDTA thickened with methylcellulose produced good results. A similar mixture without the EDTA was used to remove markings of green porous-tipped pen from a map. Water had been used with some initial results, although it stopped working before much of the stain was removed. No other solvent or solvent mixture tested under suction had worked.
General application: The object is humidified first, if possible, to prevent tide lines. The detergent paste is applied with a brush or rolled on with a cotton swab and allowed to soak in briefly. The paste is then rolled off with cotton swabs. Damp cotton swabs rolled over the surface will pick up more grime and detergent paste mixture. This process may need several repetitions. All pieces treated have had a final washing either by immersion in a shallow bath, or by flushing water through the area with a mist or spray while the piece is on the suction table. This is followed with a similar application of xylene on the suction table to remove any remaining Triton X-100.
This brief presentation was a quick look at one personal interpretation of Richard Wolbers's "New Methods in the Cleaning of Paintings."
Using the first painting that I successfully cleaned with resin soaps as a starting point, I discussed the issues involved in internalizing the new approaches to cleaning surfaces. Also discussed was how, for this painting, the results of the cleaning with resin soaps were much more aesthetically successful than those which would have been achieved with conventional solvent cleaning.
With this and the other examples, the following points were made:
The notion of a partial or selective cleaning with a gel based system is a very different concept than it is for free solvent systems. With a gel based cleaning system, a partial cleaning (or the reducing) of a varnish layer is based on fine-tuning the dissolving power of the gel. This fine tuning, under the best of circumstances, can allow a distinct portion of a varnish system to be removed; e.g., the oxidized surface, without disrupting other layers or distinct portions of a layer. The other layers are preserved based on their slightly different solubility. The layer to be removed is, more or less, entirely dissolved and cleared in the process. This is in contrast to thinning a varnish layer with solvents. With solvents, the varnish is slowly dissolved allowing the upper layer of the varnish surface to be removed before lower layers are effected by the solvents. Using a gel-based system to thin a varnish layer in an analogous manner to solvents is not advisable because of the problem of gel clearance.
Superficial or surface cleaning is a commonly used treatment step in beginning the cleaning process for textiles. It is fairly straightforward and has been successfully developed for use. When considered for use in a textile conservation treatment, vacuuming can be broken down to consider a list of refined choices. These might include: type of equipment (dental vacuum or larger wand with brush attachment), power level, and barriers needed to protect all or parts of the textile surface. However, refined choices have not been generally available when considering solution cleaning.
The predominant types of equipment and techniques used in solution cleaning of textiles in conservation have historically been borrowed and influenced from two primary cleaning traditions. One is the practice of commercial dry cleaning using petroleum solvents, and the second could be generally categorized as household or domestic cleaning using a solution of water, a surfactant, and sometimes a bleach. Cleaning textiles has tended to embrace an almost familiar "across the board approach," with the choice viewed as either wet or dry cleaning using a rather small number of choices for solutions. The practice, in general, has not been highly satisfactory.
Within the last ten to fifteen years, some alternative ways to solution cleaning of textiles have been tried along several lines. The emergence of strong professional degree programs have graduated students who have general information about all subject areas in conservation. They often have a double focus; for example, paper and textile conservation. Second, promotion of textile manufacture since World War II has resulted in the development of complicated technology to examine and test fibers and fabrics. Some of this technology has been very useful for choosing and planning cleaning approaches. In addition, textile conservators are increasingly asked to help treat ethnographic artifacts having mixed media surfaces and materials. More recently, cooperative conservation projects, involving the efforts of conservators from several different specializations, has encouraged experimentation in ways to clean mixed media artifacts, especially those in the world of contemporary art. For example, a team of conservators in Los Angeles have combined efforts to clean and treat the work of Robert Rauschenberg. The attitude exemplified by, "Oh well, it's mostly applicable to painting conservation" is becoming less relevant and seldom spoken by the textile conservator.
The seminar raises many questions which need further exploration. What would a useful "shopping list' for making a textile cleaning solutions consist of? Would it be different from that suggested for painting conservation? If so, how? The often uneven textile surface poses special problems and by contrast a painting usually has a fairly continuous flat surface for cleaning.
What are useful barriers which could be used to isolate "cleanable" textile components from those for which a "shopped for" solution would be damaging? When textile conservators move away from extensive or "overall" cleaning, is this a reaction to unsatisfactory cleaning methods? When is cleaning a textile not desirable because the process would destroy our only record of use?
Although some very good work has begun, textile conservators need to continue to define our problems before choosing the right "solutions."
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