January 2001 Volume 23 Number 1
(a collaborative project between the GCI and the Ministry of Culture and Communications of the Republic of Benin)
The Royal Palaces of Abomey, in the capital of the historic West African kingdom of Dahomey, presently the Republic of Benin, display polychrome bas-reliefs on the facades of the buildings. The bas-reliefs, a characteristic feature of the traditional earthen architecture exhibit battle scenes, weapons, and symbols of the kings, which recount their political power and victories over their enemies.
The complex of palaces, which today houses the Historic Museum of Abomey is inscribed on UNESCO's list of World Heritage Sites in Peril. In 1988, prior to the beginning of the collaboration, the bas-reliefs from the facade of the Adjalala (or official palace) of King Glélé (1858-1888) were detached from their wall support. Their removal altered them from architectural features to individual panels. Many of them were already deteriorated, others were damaged in the move and following it, as they were transported numerous times over the next several years.
In 1993, the Getty Conservation Institute and the Ministry of Culture and Communications of the Republic of Benin undertook a collaborative project to conserve the 50 remaining bas-reliefs from the Adjalala of King Glélé. The project included scientific research, training, documentation, treatment, and a long-term maintenance plan for the care of the bas-reliefs.
The presentation addresses the challenges faced in the conservation of these 50 bas-reliefs as individual panels with a range of different problems while retaining their integrity as an ensemble. The conservation treatment developed is summarized. Treatment followed the principles of minimum intervention. The focus is on the methods and materials used for the aesthetic reintegration.
The aesthetic presentation was particularly complex, due to the extent and variety of problems to individual panels, and the original nature of the bas-reliefs as an architectural ensemble. It was necessary to develop guidelines for the compensation of losses and aesthetic reintegration to arrive at the best aesthetic treatment for all 50 bas-reliefs while taking into consideration individual cases which varied from panel to panel.
Reintegration included in-filling and in-painting of lacunae in the earthen support, plaster, and paint layers. The materials used for the compensation of losses were similar to the original earthen materials used in the building construction and bas-relief modeling. Inpainting was limited to the background of the niche area, due to the fact that the relief forms showed a complex stratigraphy of color schemes. In this way the relief showed damage and wear, while the inpainting of the background greatly improved the legibility of the image. Some individual cases were treated as exceptions but always toward more minimal intervention to retain the integrity and authenticity of each panel while reinstating the unity of the ensemble.
Jackson Pollock's revolutionary "drip" or "poured" paintings have been exhaustively written about art historically. Perhaps because of their apparent self-evident nature and/or because of the extensive photographic and written documentation of the artist at work, many assumptions regarding his materials and methods have been made and given validity with repetition. Certain visual effects and painterly developments have been attributed to his use of specific materials with little or no technical investigation to substantiate these assumptions.
The purpose of this portion of the study (carried out with Dr. Susan Lake of the Hirshhorn Museum and Sculpture Garden and with Michael Schilling of the Getty Conservation Institute) was to determine what materials were actually used not only in the drip paintings but in several works dated before and after these as well. Eleven paintings by Jackson Pollock were studied and analyzed for their paint composition (pigment and binder) using PLM, SEM-EDS, XRD, FTIR, and GCMS. Additionally, the paint materials left in his studio were examined and likewise analyzed.
This study compares two materials, a vinyl chloride eraser and a polyacrylamide gel block eraser, in their ability to surface clean acrylic emulsion paint on paper. Four different colors and two different surfaces, smooth and brushed, were tested with both cleaning materials which were soiled with an artificial grime. The results were analyzed with a visual comparison of the clean surface with photographs taken at 50x and SEM photomicrographs at 90x and with a quantitative comparison of colorimeter readings before and after cleaning. Neither cleaning material was completely successful in all of the tests. The efficacy of either material appeared dependent on the components of each specific acrylic paint tested.
Dawne Steele Pullman
A five month grant from the Japan Foundation enabled limited research of a specific Japanese modern artist Toshinobu Onosato (1912-1986). This included research of materials, techniques, and optimum lighting in museum spaces with specific research on color temperature for his art works. Conservation of other Japanese artists' paintings and their similar conservation problems compared with Western art was insightful. This experience also introduced me to the ways and the world of art as well as the business of art in Japan.
Camilla Van Vooren
This talk discusses the development of Gamblin Conservation Colors, summarizing research conducted by Mark Leonard, E. Rene de la Rie, Jill Whitten, and Robert Gamblin, which the authors recently presented at the IIC Congress in Melbourne. The discussion will include comments from conservators who where involved in the use of the material in its experimental stage, as well as those who have purchased and used Gamblin Conservation Colors since they became commercially available late last year.
This talk will consider some of the causes of tears and the problems involved in their repair with an emphasis on the correction of associated planar distortions. Several ways of reinforcing tear mends to inhibit return of distortions in plane are examined. The talk will describe the localized use of G10 strips adhered to the canvas back with Beva film as an easily reversible type of tear mend support. The repair of an extensive compound tear in a painting by Juan Gris will be the focus of the last segment of the presentation.
Lasers as a tool for art conservation have a history going back over 25 years. Laser induced desorption of contamination on art objects has been demonstrated on a variety of materials including stone, organics, metals, and glasses,to name a few. Further, the use of lasers as a tool for the cleaning of stone is well developed in many parts of Europe where industrial pollutants, high in sulfur compounds, have done a great deal of damage to stone monuments. In this case various laboratories within the European Union have been able to conduct studies regarding the effects of laser cleaning on the surface of the object.
As the use of lasers to clean other materials is investigated and debated, it is important that appropriate studies of the changes to the surface of the object are conducted. Potential damage to the cleaned object over the long and short term is a very real risk. To date little surface analysis has been done on many of the materials that conservators might potentially like to clean.
In an effort to fill this gap, the Los Angeles County Museum of Art has undertaken a study of the effects of laser irradiation on specific metals and organics. Sample preparation will be discussed. Protocols and initial results of tests on organic (primarily ivory) and metal (primarily silver and copper) substrates "cleaned" using laser ablation will be presented.
The relative merits of various analytical techniques such as X-ray spectroscopy (PIXE, EDX), Tof-Sims, microscopy (optical, SEM, AFM), and various other spectroscopic techniques will be assessed and the potential effects of observed surface changes will be discussed. Finally, development of a plan for accelerated aging studies of laser irradiated art materials will be described.
This talk summarizes the long history of discussions and debates in Europe surrounding loss compensation in paintings. It looks at the origins and evolution of criteria for successful retouching. It will examine the beginnings of retouching in the style of the original artist; the use of reversible retouching materials in the 17th and 18th centuries; the search for stable materials in the 18th and 19th centuries; the articulation of specific training and skills required for the inpainter; and the 19th-century movement against retouching.
Mary Piper Hough
The aim of this study was to examine a variety of local treatments, orthodox and novel, to flatten cupping and restrain its reappearance in localized cracks. Local treatments were investigated in order to forestall overall lining and marouflage treatments. These treatments were applied to cupped cracks in slack model paintings made for the study.
The model paintings were made to follow a technique often used by modern and contemporary artists: oil paint on acrylic ground on cotton duck fabric. Linear cracks were made by the same method in each of the models. Profiles of the cracks were monitored with a mechanical scanner to document the cupping heights before and after treatment.
Local crack treatments included adhesion of a solid plate for reference purposes, moisture and heat relaxation alone, variations on the application of small strips of material across the crack reverse, application of a local size - with and without the addition of strips, and a butt joint.
Two stages were planned for testing treatments on the cracked model paintings: slack for the initial period, then taut. The results are given for the paintings in the slack condition only. The treatments were evaluated in terms of profile measurements and visual assessment. Three of the treatments with strips of various materials applied to the crack reverse appeared promising: strips of steel, epoxy-coated glass filaments heat-cured, and epoxy-coated polyester threads heat-cured. These gave good results in terms of restraining cupping and not surfacing. All methods showed measurable stress relaxation, i.e., return of cupping, but the rate varied from hours to weeks (and by extrapolation from the graphs) to centuries, depending on the viscoelastic properties of the materials.
Although the history of photography and its various processes has been extensively studied by scholars and conservators, the history of photographic mounting is often overlooked. This paper will trace the origins of the practice in the traditional mounting of prints and drawings, through the evolution of photographic albums in the nineteenth-century, to the artistic flowering of the Pictorialist style at the turn of the century. Nineteenth-century materials and techniques for mounting will be discussed, in addition to stylistic developments. This paper builds on ideas discussed by the author at a previous WAAC Meeting.
Whereas significant scholarship has been devoted to the art of netsuke, little attention has been devoted to the techniques by which they are fabricated. The current study seeks to fill this void, specifically with regard to netsuke carved from ivory. The research to be presented was gathered during a technical study and cleaning of approximately 100 ivory netsuke in the collection of the Los Angeles County Museum of Art (LACMA) that took place between September 1998 and September 1999.
Direct observations made during visual examinations of individual netsuke are supplemented by research of available literary sources and indirect experimentation with ivory facsimiles in order to draw conclusions about the ways in which ivory netsuke have been fabricated from the 17th through 20th centuries.
In the context of the project at LACMA, technical understanding of the netsuke was requisite to understanding their current condition and developing a cleaning strategy. The types of deterioration encountered and treatment methods will be discussed.
Though the cleaning process was generally straightforward, the removal of stray ink marks from a small number of netsuke has been unsuccessful with traditional conservation methods. The problem is now being studied in collaboration with the Laser Research Facility at LACMA, with some very interesting results. The preliminary findings of this research will also be presented.
J. Claire Dean
In 1948 a Greek immigrant, Tom Stefopoulos, began a series of paintings on the support columns of the Lovejoy Ramp (a 1926 bridge off-ramp on to Lovejoy Street carrying traffic across the Willamette River and over rail-yards into an industrial neighborhood of northwest Portland known as the Peal District). Stefopoulos, a trained artist, worked as a watchman and switchman for the railway and "between trains" painted scenes depicting Greek mythology, Americana, and Biblical imagery. Both the paintings and Tom became part of Portland urban legend.
With the demise of the railroads the area became a large wasteland which the City of Portland has made the focus of major urban redevelopment. A new plan to erect high density housing and retail locations in the area of the Lovejoy Ramp called for its demolition along with Tom's paintings. Led by an innovative architecture and design studio, the community rallied to save the paintings and they are now scheduled for re-erection as a massive piece of new public sculpture spanning the current Amtrak rail lines, close to their original location.
This paper will describe the efforts to save the Stefopoulos murals and the close collaboration between the architects, designers, local community, and a conservator, all working to create a huge piece of new art out of old art that would make Tom Stefopoulos proud.
Susan R. Schmalz
Textile conservators are increasingly exploring nontraditional compensation techniques for loss. Alternatives to dyed fabric inlays include a wide variety of hand-coloring methods on textile supports. This paper focuses on a treatment technique incorporating acrylic paint on silk crepeline devised to visually re-integrate massive losses to a chintz border on a mid-19th-century quilt.
The quilt is from the collection of Hampton House, a National Historic Site in Maryland, inhabited for more than two centuries by the illustrious Ridgely family. The numerous damages to the quilt border made traditional fabric inlays impractical. The treatment solution involved stabilizing the deteriorating brown chintz and concealing the exposed batting with painted crepeline overlays.
Golden Artists Colors acrylic paint was selected after numerous test swatches of paints, inks, and dyes were assessed for aesthetic appearance, ease of application, cost, reversibility, and stability in fluctuating heat and humidity. This effective technique provides another valuable option for textile conservators.
John Griswold and J. Claire Dean
Under some very specific circumstances, it is necessary to apply an inpainting medium directly to a stone substrate. The most compelling example is the need to visually reintegrate scratched graffiti on petroglyph or pictograph panels.
After over 5 years of field testing, a workable technique for the inpainting of scratched graffiti on basalt boulders having heavy deposits of "desert varnish" has been developed. The first years of the study explored the suitability of various inorganic binders for mineral pigments. More recently, a specialized technique using mica-based pigments and alkoxysilane has been refined to help achieve the rich, iridescent reflective surface of the "desert varnish."
This method is promising, particularly because it circumvents the potentially disastrous use of commercially marketed chemical solutions for creation of artificial desert varnish. Such products are clear solutions that darken fresh stone surfaces through chemical deposition of ferro-manganese compounds from an alkaline solution. Their use and negative results have been reported in Studies in Conservation.
This paper focuses on the technical aspects of development and testing of the inorganic inpainting medium, and the successful collaboration of Park Service and City of Albuquerque Open Space personnel with Dean and Associates Conservation Services and Griswold Conservation Associates in determining its effectiveness and limitations. The ethical considerations of the practice of visual reintegration directly adjacent to pictographs, and the potential for other conservation-related uses of this technique are also mentioned.
James R. Druzik
In the late 1980's the Getty Conservation Institute funded a research project carried out at the California Institute of Technology designed to investigate the risks to works of art from indoor airborne particles. At the time very little was known about the concentration and fate of indoor particles in museums and their rates of deposition onto surfaces. Of primary concern was the deposition of fine elemental carbon (soot) particles.
These particles, being black, contribute to the slow aesthetic degradation of painted surfaces, and being small, 0.05 to 1.0µ in diameter, tend to migrate deeply into porous surfaces where they are difficult to remove. Fine carbon particles are also hard to remove by the filters most commonly employed in standard heating, ventilating and air conditioning (HVAC) systems. Therefore, an assessment of indoor/outdoor particle concentrations and their deposition rates on vertical and horizontal surfaces was critical for estimating soiling rates and developing protective strategies for exposed museum collections.
During two-month periods in the summer and winter of 1988, five institutions in Southern California were investigated: the Norton Simon Museum, J. Paul Getty Museum, Scott Gallery of the Huntington Art Gallery and Library, the Southwest Museum, and the Sepulveda House. These institutions ranged from an historical house museum with ventilation through open doors and windows and outdoor air exchanges ranging from 1.6 to 3.6 air changes per hour, to museums with fully equipped HVAC systems having low outdoor air exchanges (<1 per hour) and high air recirculation rates (5-8 per hour).
In general, measured particle deposition velocities to vertical indoor surfaces ranged from 10-6 to 10-5 m/s depending upon particle size, and regardless of particle type, the fraction of outdoor air particles deposited onto all surfaces ranged from 0.l-0.5% for diameters in the vicinity of 0.15µ, up to 90% for particles larger than 20µ. The rate of elemental carbon particle accumulation on vertical walls ranged from 0.08-2.7 mg m-2 day-1. The measured indoor particle characteristics agreed well with predictions made from their mathematical model of indoor aerosol dynamics based upon measured outdoor particle characteristics and building parameters.
To estimate the soiling rates from the deposition characteristics in these building types it was necessary to relate surface deposits to the level where the soiling became "just perceptible" to a standard human observer. Efforts to determine this level had been carried out twice previously, once in the mid-1950's and then again in the 1970's. Both efforts agreed that a coverage of approximately 0.2% of the surface by black particles was just visible.
As a result, the estimated soiling times associated with the five Southern California museums ranged from approximately 0.3-18 years. This study was published in two reports from the Getty Conservation Institute in 1992 and 1993. Individual chapters of these reports were subsequently published in the scientific peer-reviewed air pollution literature (Nazaroff et al.).
In the summer of 2000, "A Study on the Human Ability to Detect Soot Deposition onto Works of Art" was published in Environmental Science & Technology by Bellan, Salmon, and Cass. Bellan utilized methods for depositing black particles and characterizing surface coverage that was far superior for modeling soot particles than earlier research.
He showed that, even with the ability to view a clean white area edge-to-edge with a soiled one, the onset of the point where a normal observer could just begin to detect that a surface was becoming soiled by microscopic soot particles occurred at approximately 2.4% surface coverage. This was a 12-fold increase over the earlier estimates. This new value expanded the soiling times for Southern California museums from 0.3-18 years to 4-216 years for the institutions previously studied.
In reviewing the original five museums it is clear that the Norton Simon Museum represents a unique class of institutions in its ability to provide a very clean indoor environment. The Simon Museum provides more than twice the protection from soot soiling than the Scott Gallery, yet both seem to be typical, modern air-conditioned museums. Both have fairly similar outdoor air exchange rates and indoor air recirculation rates.
The main difference between these two buildings is that the Norton Simon Museum deposition velocity data agrees with predictions for deposition from a forced laminar flow of ventilation air along its walls owing to its use of the entire ceiling as an air plenum for the HVAC system (similar to the air flow system used in clean rooms). This is not a common feature for museum design although the tendency is toward this in new museum construction projects.
At the other extreme, the Sepulveda House with its completely unprotected ventilation strategy and 4 year time to the onset of soiling is so poorly controlled that it is unlikely to be used to house sensitive and extremely valuable art collections; indeed it is used as an historical house museum in which the building and its furnishings are on display.
If the premise is true that the Scott Gallery, Getty Museum, and Southwest Museum with their mechanical ventilation systems are representative of the majority of structures that house contemporary art, then the exposure times prior to the onset of perceptible soiling of vertically-oriented surfaces ranges from 24 to 86 years with an average time to perceptible soiling on a white surface (based on an edge-to-edge comparison) of approximately 50 years.
The significance of this new figure is that turning the clock back 50 years puts us near the start of Color Field paintings. Thus the paintings of artists such as Morris Louis, Ellsworth Kelly, Jackson Pollock, Kenneth Noland, Mark Rothko, Helen Frankenthaler, Clifford Still, Franz Kline and Willem de Kooning, and the thousands of square meters of vulnerable canvas they have created, are now entering a stage where soot deposition will become an ever increasing problem for future conservators. That this new estimate may be a clarion of impending events is witnessed by the Tate Gallery in London which has recently begun a program to clean their Mark Rothko paintings.
The Revolutionary Preservation System (RP System)tm is an oxygen absorbing system produced by the Mitsubishi Gas Chemical Corporation that is marketed for usage with museum artifacts, especially metal artifacts because of the product's purported ability to function in low humidity environments. This project was undertaken to evaluate the efficacy of the oxygen-scavenging RP System.
The potential applications for this product would be particularly useful at archaeological sites, especially with metals suffering from chloride corrosion. This study examined the performance of the oxygen absorbing system and analyzed the components for their appropriateness with museum artifacts. A discussion on the ease of use and the economic viability of this product is included with the conclusion.
Duane R. Chartier
Technology in the last three decades of the last millennium has produced a wide variety of composite materials many of which have been adapted for use in conservation. However, these materials have not always been selected wisely nor have they been adequately compared to their historic predecessors.
ConservArt Associates, Inc. has extensive experience in mural and contemporary art conservation. This has permitted the critical examination of older marouflage techniques as well as development of new ones. In particular, composites developed for aerospace applications have been adapted for large-scale contemporary mural installations as well as structurally and seismically competent supports for older works of art.
This paper presents a brief discussion of solid supports and particularly composite materials used in conservation.
Fading of some modern printing inks exposed either to north daylight through window glass with and without plastic glazings, or to tungsten lighting conditions qualitatively similar to gallery lighting, is being monitored by reflection spectrodensitometry.
The ink samples under study are Hewlett Packard cartridge inks for the 700 series DeskJet printers, several colored inks in 1990 Iris inkjet prints from Disney, and contemporary pigmented inks formulated for an Epson series 9000 printer. The HP inks are printed on multipurpose bond paper or Blue Jean rag paper, and the Iris prints are on a cream colored wove paper. The pigment inks have been printed on various paper and textile supports. Fading and discoloration are assessed by following both CIE L*a*b* tristimulus values and Density T values measured with an X-rite Model 938 spectrodensitometer. Each system of measurement provides useful information on the behavior of these modern three-color printing systems.
An informal progress report on this long-term study will be given. The following observations have been made so far. Trends of change are detected instrumentally before color changes are obvious to the eye, even for side-by-side comparisons of covered and exposed sections of a color patch.
The importance of removing all wavelengths of UV light when any of these materials is displayed cannot be overemphasized. When exposed to tungsten light with glazing that blocks all UV, the Iris inks appear to be more stable than their anecdotal reputation might suggest. Some of the pigment inks, which have been devised specifically to provide light stable colorants for contemporary digital print artists, fade slightly in these gallery lighting conditions.
Pesticides including herbicides, fungicides and various other substances have been used to prevent, destroy, repel, or mitigate pests in order to preserve museum collections. As a result of the Native American Graves Protection and Repatriation Act (NAGPRA), federally recognized American Indian tribes have begun to claim and receive certain cultural objects previously held with museums and Federal agencies.
This means that these materials, now contaminated with pesticide residues, are again being handled and used in traditional ways. It is the actual repatriation or the transfer of pesticide contaminated cultural objects from museums to tribes for culturally appropriate use, storage, or disposal, which has made this both a serious and urgent concern.
A range of specialists including American Indians, conservators, curators, industrial hygienists, chemists, and medical toxicologists, are needed to combine research methods with historical information and scientific techniques in order to determine the nature of these pesticide residues, their health hazard, and the potential to remove them. Various laws have made this a legal issue, voices from the American Indian tribes have made it a moral issue, and the involvement of professional conservators has identified various ethical issues.
This presentation will report on some of the activities currently underway regarding NAGPRA regulations, the concerns of tribal representatives, the recovery of an institutional history of pesticide use, the development of material characterization tests for the detection of pesticides, and aspects of working with a multi-discipline team of specialists.
To inpaint on a 3-dimensional object, a conservator must think below the surface, to replicate not just the skin of a sculpture but to the material that constitutes the substrate below. The thread that runs through this topic is loss compensation and the ethical decisions we make as a team for each object or sculpture.
There is a different approach for each individual work of art, not only the appearance and aesthetics must be considered but also, the structural stability, physical integrity, and the original and contemporary cultural significance. Each medium represents a different challenge. There is no single method in this process. In this presentation, I would like to illustrate a range of treatments covering metal, ceramics, wood, bronze, and composites. I will discuss the extensive collaboration and teamwork with curators, scientists, preparators, and colleagues in the field to derive the final solution for a successful treatment.
Tram M. Vo
This paper will address critical factors to consider in inpainting damaged and deteriorated photographic print materials. Factors include the extent of compensation appropriate, artist's intent, aesthetic consideration, and general condition. A brief review of inpainting materials and techniques (including advantages and disadvantages) commonly used by photograph conservators will also be provided.