Vincent Beltran from the Getty Conservation Institute presented this talk in the Research and Technical Studies session. The study presented examined the effects of anoxia and hypoxia on light-induced color change in a sample set containing a variety of materials. The goal was to examine the use of these environments in storage and exhibits as part of an effort to improve the experience for visitors viewing light-sensitive items.
The talk was organized into four parts: “Introduction,” “Experimental Method,” “Microfader Results,” and “Comparison to Lightbox Study.”
In the introduction, Beltran reviewed traditional practices to mitigate the damaging qualities of light. For example: reduce light levels, limit exposure time, rotate exhibit items, and store items in the dark. He then provided an overview of the photo-oxidation process, and the theories behind the use of anoxic and hypoxic environments for storage.
A 2012 study of 125 colorants exposed in a halogen lightbox for 17.5 MLux hours at 22° C, 40% RH with oxygen levels at <10 ppm indicated that 90% of these items studied showed reduced color change as compared to the same items stored in air. To the authors, the logical extension of this study was to transfer the test to the microfading tester and compare the results.
The design of the lightbox for the microfading tester study involved a xenon light projecting through ¼” starfire glass to items on a sample stand. Light was reflected to a spectrometer located above the glass. A ½ cm gap existed between the samples and the glass. The microfader was located above the case while the colorants were inside the case. The colorants consisted of 3 blue wool, 4 organic dyes, 2 leaves, 1 grass, 5 gouaches, 1 watercolor with prussian blue, 1 Kremer Prussian Blue, and 1 Crystal Violet. The colorants were exposed for 5 MLux hours in air, anoxia (<200 ppm oxygen), and hypoxia (1% and 5% oxygen). Reflectance spectra were obtained and combined for a color change plot.
The results of the microfading tester study showed that for the most part color change in air is higher than that in anoxia. Anoxic environments seemed to be generally equivalent to the 1% oxygen environments. A few colorants exhibited a slightly decreased change in the 1% environment but Beltran indicated that these results were inconclusive. A few exhibited increased change in the 1%. Environments with 5% oxygen tended to exhibit more change than anoxic or 1% but generally not as much change as found in air. The exception to this is Prussian blue, which shows the opposite behavior – an air environment showed the least change, 5% followed, and 1% and anoxic showed the most change. Overall, the results showed that 12 of the 18 colorants exhibited greater change in air while only one (Prussian blue) exhibited the greatest change in anoxia. Generally, hypoxic environments exhibited less change than air.
Beltran then presented a comparison between the 2012 study and the more recent microfader study. The main differences in the studies were as follows:
In general, the color change with the lightbox test was higher than that seen with the microfader, though some samples showed changes which were roughly equivalent. Most items showed similar behavior between the two techniques but the lightbox displayed increased change. The differences in the studies were typically within one blue wool step, and the study was able to consistently classify relative color change between the two techniques. However, Beltran stated that there is reciprocity failure between the two studies.
Future goals of this project are to repeat the analysis with more samples, examine the effect on reciprocity for the microfading tester at reduced light intensity, and study the color change in various RH and temperature levels.
Questions were as follows:
Q: In cases where the microfading tester and lightbox didn’t agree, is the lightbox the more reliable?
A: In general, lower light exposure tends to be closer to what you’d get with the microfading tester but that doesn’t mean reciprocity is holding.
Q: Has the microfading tester been tried with a halogen bulb?
A: No, they tried to modify a halogen source but it didn’t do much.
Q: Were control samples used?
A: No, they were not..
Those who have beheld the Hall of Northwest Coast Indians at the American Museum of Natural History and its extraordinary “totem poles” will instantly recognize the potential scope of any study or treatment of such massive artifacts. The Hall of Northwest Coast Indians, which opened in 1900, highlights the traditional cultures of the native peoples of North America’s northwest shores from Washington State to southern Alaska, including the Kwakwaka’wakw, Haida, Tlingit, and others. (Source: AMNH.org)
These objects are housed in the earliest wing of the museum, curated at its inception by Franz Boas, “the father of American Anthropology”, who organized the early acquisitions of the museum according to a revolutionary argument: that of “cultural relativism” in opposition to a chauvinistic, social-Darwinist organization that put “primitive” peoples at the bottom of an evolutionary tree, the pinnacle of which was white America. Today, this hall holds a landmarked status and remains relatively unchanged, as the poles are very hard to move.
Ten years ago, a renovation of the hall was proposed. Although the recession thwarted plans, the objects were still in need of stabilization and aesthetic improvements. Because this project—from its inception, through the research, testing, and execution stage, was so expansive—Samantha Alderson reminded her audience that her talk could only represent an overview of a four-year process. Those interested in a specific aspect of the project can look forward to in-depth, forthcoming publications.
One of the more important aspects of the research phase, and a professional obligation that is indispensable to the curation and conservation of native materials, was the consideration of ethical issues and provenance information. Most of these pieces entered the collection between the 1880s and the 1920s, and the majority has been on continual, open display since their arrival. Their presence in AMNH’s collection is widely acknowledged to be ethically complicated in itself, representing an era of unscrupulous dealing in Northwest Coast artifacts. (To read more about “Indians and about their procurable culture,” consult Douglas Cole’s, “Captured Heritage: The Scramble for Northwest Coast Artifacts,” about the coincidence of a taste for these native artifacts and the establishment of many of the country’s foremost natural history collections. (p.xi)]
The carvings, including the carved columns most commonly described as ”totem poles,” would have had numerous functions within their originating cultures: house frontal poles holding entry portals to buildings, interior house posts, welcome figures, memorial poles, and mortuary posts [For a technical study on these types of carvings, please consult “Melissa H. Carr. “A Conservation Perspective on Wooden Carvings of the Pacific Northwest Coast.” Wooden Artifacts Group Postprints. 1993.].
To further hone their understanding of provenance, the 2009 CCI “Caring for Totem Poles” workshop in Alert, Canada, allowed the authors to travel through British Columbia with curatorial consultants, native carvers, and native caretakers, in order to study the techniques of manufacture. It was also important to keep abreast of the expectations of the native communities that might be borne out over the course of any treatment intervention or re-installation campaign.
The original aim of this project was to provide structural stability to those carvings which exhibited highly deteriorated surfaces caused by the weathering and biodeterioration in their original environment. These instabilities were often exacerbated by inappropriate environmental conditions and restoration interventions in the museum. The most significant issue requiring treatment was the presence of wood rot, insects, and biological growth, present in the original environment and continuing to run their course.
Although climate control was installed in 1995, soot from the age of coal heaters and lamps still blanketed the inaccessible areas of the objects. Dust from visitor traffic also dulled them, as the hall is adjacent to the entrance to the IMAX theatre. Routine and well-intentioned cleaning was ineffective against a century of accumulated grime and dust and was causing surface loss. The location of the Hall of Northwest Coast Indians in relation to the IMAX theatre
As there is no barrier between the objects and the visitor, touching has caused burnishing and scratching. The unfinished wood readily absorbs skin oils; and graffiti and adhered chewing gum had also become a most-unfortunate problem.
Early interventions after acquisition had caused condition problems of their own, as old fills had a hardness or density that is inappropriate for soft, weathered wood. These fill materials were only becoming more ugly, unstable, crumbly, and cracked with age.
All of these factors, taken together, provided a huge impetus for treatment.
To begin the treatment-planning stage, the conservators at AMNH performed examinations under visible and UV radiation and mapped the observed conditions and materials using a streamlined iPad-based documentation protocol. In some cases the restoration materials observed provided evidence of institutional and condition history. Although there were almost no previous treatment records of these objects, comparison with archival photographs of many of the objects showed the rate of deterioration since acquisition and provided clues as to dates of interventions and installation history.
In summary of the object-treatment stage, vacuums and sponges were first used in an attempt to reduce some of the dinginess of the surface and to increase the legibility of the painted designs. The many resinous and waxy coatings had trapped so much dust, however, that this treatment did not always have a satisfactory result.
The question of solvent toxicity held sway in all aspects of treatment, as operations were completed in makeshift spaces outside of the lab, due to the size of the objects; these areas had no fume-extraction infrastructure. Luckily, plaster fills could be softened with a warm-water-and-ethanol mixture and carved out. Temporary conservation lab set-up in the gallery (See treatment photo gallery here).
Butvar B-98 and Paraloid B-72 were selected as potential consolidants and adhesives. A 5-10% Butvar B-98 solution in ethanol (i.e. without the toluene component for safety concerns) was used for surface stabilization, and Paraloid B-72 in acetone was used for adhesion of splinters and detached fragments. Karl Knauer filling splinter edges.
Fills were designed using different materials depending on the location on the object. These were intended to reduce damage during installation, display, and regular maintenance. If the fill was not visible, shapes were cut from Volara, beveled, and adhered in place with Paraloid B-72 along the edges. These were often necessary on the tops of the poles to cover the deep voids of deteriorated wood. Some losses were back-filled with tinted glass micro-balloon mixtures of different grades and different resin-to-balloon ratios where appropriate. As some paints were solvent-sensitive, certain fills required the use of Paraloid B-67. The final fill type was a removable epoxy-bulked fill to compensate for deep losses in visible areas. These areas were first filled with polyethylene foam to prevent the fill from locking in. The edges of the fill area to be cast were protected by tamping down teflon (plumber’s) tape which conforms nicely to the wooden surface. West System 105 Epoxy Resin—with “fast” 205, “slow” 206, or “extra-slow” 209 hardeners—was used in different proportions to 3M glass microspheres and pigments to give fill material with various hardness, curing-times, textures, and colors (See Knauer’s upcoming publication in ICOM-CC Warsaw 2013 for more details). This method is notable for its invisibility, its reversibility, and its rejection of phenolic micro-balloons, which are an unstable and unsuitable and were historically used for such a wood fill merely for their brown color. Once cured, the bulked-epoxy (and the plumber’s tape) were removed and the fills were then tacked into place with B-72 to produce an aesthetically pleasing and protective cap.
Many losses which were previously filled were left unfilled, as would have been the case it they had been collected and treated today. Crack fills were incised so as to retain the appearance of a (smaller) crack.
Once the surface and structure was stabilized with the consolidation and filling operations, the team turned their attention to the various paint films to be cleaned. Many of these were proteinaceous but some were more similar to house paints. This data was consistent with the ethnographic findings and with current native practice. No preparatory layers were used, and the pigment layers were often very lean.
PLM, XRF, and SEM-EDS, as well as UV-FL imaging, thin sections, and analysis with FTIR was undertaken. Some binder analysis was also possible, but this was complicated by historical treatments. Interpretation of epi-fluorescence microscopy results was also thwarted by the presence of multiple coatings, the inter-penetration, -dissolution, and bleed-through of layers. As many as four different types of coatings were identified, and understanding and addressing the condition issues caused by these coatings became a primary concern. Cellulose Nitrate was often applied to carvings in the early 20th century. Whether this was to refurbish or protect, it has developed into a dark-brown layer which is alternately hazy and glossy and which obscured the original surface appearance. Lower regions evidenced PVA or PVAc on top of the Cellulose Nitrate. Shellac and dammar are present in isolated locations, as is an orange resin which eluded identification (even when analyzed with GCMS).
Although identification of these coatings was attempted, removal was not originally planned due to the difficulties designing a solvent system for its reduction, considering the variation in sensitivities, the interpenetration of the layers, and the unknown condition of the original paint films beneath. This plan changed when the poles were deinstalled for construction.
The treatment design was largely aided by the isolation of four house posts in the collection made by Kwakwaka’wakw artist Arthur Shaughnessy. Arthur Shaughnessy carving one of these poles (Photograph by George Hunt, copyright AMNH).
Commissioned by AMNH in 1923, these had never been installed outdoors but which had been coated in the same manner and exhibited in the same space. This allowed for the development of controlled methods for coating reduction.
A Teas table (or Teas chart) was used to identify potential solvents or solvent mixtures, which were tested over every color and monitored for any leaching or swelling. These initial tests were deemed unsuccessful.
In areas without paint, film reformation with acetone reduced haziness or glossiness. Where the coating was completely removed, the wood was often left with an over-cleaned appearance which necessitated some coating redistribution with MBK, MEK, and propylene glycol. Wherever possible, gels were used to reduce the exposure to toxic solvents. In painted areas, the large variation in solvent sensitivity, the inconsistency of media binders, the varying porosity of the wood, and the changing direction of the wood grain required that the conservators work inch-by-inch. DMSO, a component of “safe” stripper, and NMP were controllable over certain colors but caused considerable swelling.
February 2012, the museum saw the reinstallation of the Shaughnessy poles, marking the effective conclusion of the testing period and the successful management of a challenging triage situation by conservation staff.
It was Kwakwaka‘wakw artists like Arthur Shaughnessy who kept carving traditions active when the Canadian government prohibited the potlatch ceremony in 1885. The ban was lifted in 1951, after AMNH’s acquisition of the house posts.
The completion of treatment represents an important opportunity to educate the public: Although these monumental carvings are exhibited in a historic wing of the museum, we need to dust them off and remember that these carvings represent very, active traditional practices and communities.
There is still the need to develop more systematic solvent strategies, as well as to consult with a paintings conservator. But it is clear that these objects stand to look much improved after the grime and coatings are removed or reduced and the objects are thoughtfully reintegrated with a well-designed fill system. Thanks to the remarkable talents of the AMNH team, these stately creations are finally commanding the respect they deserve.
In this talk, Lieve Watteeuw showed images produced by the Reflectance Imaging for Cultural Heritage (RICH) project and demonstrated the functionality of the Mini-Dome module. I was excited to see this presentation after reading advertisements for the “New Bownde” Conference at the Folger Shakespeare Library last year, in which the RICH project and Mini-Dome were featured. Fortunately, for those unable to attend the presentation, extensive documentation about the project is available online through the project’s webpage and blog. The Mini-Dome module
The Mini-Dome module is a small, hemispherical-shaped imaging device that is tethered to a laptop. The module creates dynamic digital images through polynomial texture mapping, a technique commonly referred to as Reflectance Transformation Imaging (RTI). This technique involves taking a series of images from a fixed camera position, while changing the angle of lighting, in order to reveal the surface of an object. The original dome was created in 2005 at Katholieke Universiteit Leuven for reading cuneiform tablets, but has since been used to image bindings, illumination, wax seals, cuir bouilli, and other cultural objects. The current module is equipped with a single 28 MP digital camera and 260 white LED lights to capture a total of 260 images in approximately four minutes. Watteeuw showed a video of the Mini-dome in action during her presentation, but readers can view a similar video here. Example of images and filters. KU Leuven, Maurits Sabbe Library, 16th century SPES Binding, panel stamp on brown calf leather.
After capture, Watteeuw described how the images are processed by software and interpreted by seven dynamic filters. She demonstrated some of these filters, including sharpen, shading, generate models, line drawings, and sketch. Using the mouse or interface buttons, the user can zoom in, drag the image, or change the direction of lighting in real-time. For those that would like to experience the software interface, a web viewer is available here. Watteeuw reports that the software suite can also export to 3D shaded or rendered modes.
Watteeuw’s presentation included a demonstration of a measurement tool built into the image processing software. The tool can be used to measure the distance between two points or generate a height map for a portion of the object. This blog post includes an image of a height map created on the blind-tooled surface of a leather binding. Watteeuw explained that by scaling the image, the measurements can be accurate to 10 microns.
Watteeuw’s presentation included several examples of how the Mini-Dome could be used to learn more about the production of a binding. Images of a late 15th century book of hours were manipulated with filters to show tool marks on the uncovered wooden boards, providing evidence of how the boards were shaped and the lacing of the sewing supports. A second example showed a 16th century book (pictured above and described here), in which the binder scored a vertical line in the leather to align a large, central impression. Watteeuw described instances in which previously unknown marks or designs were revealed by manipulating the filters or direction of the lighting, such as three leaves emerging from an emblem design, or shallow impressions from a decorative roll being more clearly defined. This tool could be quite useful for identifying individual finishing tools and documenting how they changed or became damaged over years of use.
In addition to leather bindings, Watteeuw shared images of Belgian damask silk, remains of a ribbon, and embroidered bindings from the Folger Shakespeare Library. Once again, the dynamic filters in the software suite were applied in order to enhance details of the objects. The “sketch” tool provides clear images of weaving and embroidery patterns and could be very useful to textile historians and conservators. The measurement tool could also be used to gather data on the thickness of threads or cord used to construct the object. The Micro-Dome module fitted to a copy stand.
The RICH project will continue until 2015 and additional investigations are already underway. Watteeuw reports that the topographic data from an object is exportable into spreadsheet form. Engineers on the team are currently exporting high points of objects scanned to create a large data set for further analysis. Additional projects include the development of optical character recognition (OCR) for specific tool shapes or patterns on bindings. Testing is proceeding on a smaller “micro-dome” (pictured above) that is constructed in two pieces so that it can be placed inside the opening of a book to capture images of the gutter or surface of a page. Watteeuw described a student research project currently in progress to measure sewing in manuscript textblocks.
Two questions were asked by audience members following the presentation. The first individual asked if a database of the existing images is available. Watteeuw answered that an open access database of all images captured would be ideal; however, since this is a research project using prototypes, the team is collaborating with institutions to link with existing databases. A second audience member asked if any attempts had been made to identify tools of various workshops. Watteeuw replied that a corpus was needed before any comparisons could be made.
Advanced imaging technologies, such as RTI, offer tremendous opportunities for the study of cultural objects and for digital libraries in general. The RICH project has produced a suite of tools that could be used by scholars and practicing conservators to gain a better understanding of an object’s composition and production. Wider use of devices such as the Mini-Dome in imaging collections of note and greater access to the software suite is required in order to exploit the full potential of the technology.
Faddan More Psalter
John shared with us his particular torment, a project that has occupied him daily for over six years, a highly deteriorated psalter uncovered from a peat bog in 2006. He still has his sense of humor, even though he freely admitted the project was pretty nightmarish at times. The psalter was uncovered from a commercial peat bog in July of 2006. Research suggests that the sphagnum moss in these bogs is what helps organic material survive so much better there than in regular soil, as the moss has a tanning effect on the organic material.
Once the psalter was uncovered, work stopped in order to rescue the fragile book. The psalter was covered in a wet layer of peat, then silicone Mylar and finally cellocast resin bandages were wrapped over the psalter to keep it wet until help arrived. This was exactly the right thing for the bog excavators to do. These men were not archaeologists or conservators themselves, but they knew what to do to keep it stable until conservators could arrive due to extensive museum outreach in the area. Local museums have provided a lot of training in order to help protect the wealth of archaeological materials located in Ireland’s bogs – most of which are commercially owned. Back at the lab in Dublin, the manuscript was kept wet and cold – at 40°C in a walk-in fridge. The media hyperbolically reported the discovery of the Psalter as being an apocalyptic omen due to a misidentification of one of the psalms. Really, psalters like this were used by monastic novices to learn their bible.
John’s first goal was to establish a collation map of the psalter. This usually easy task took two years due to the extensive trauma to the book. The psalter has five quires, 60 folios, no flyleaves, and it does not follow the insular nor the continental tradition of orienting the hair and flesh sides of the parchment folios. As John said, it seems to be “in the best Irish tradition, of completely ad hoc”.
Using a grid system, John mapped out each chunk of parchment before putting it through the drying process. He used a database to compile the veritable mountains of information the treatment of the Psalter generated. They cleaned the manuscript with water, removing thousands and thousands of seed pods with tweezers. One of the most challenging parts of the project was the “letter fishing” the group had to go through, to snag words and letters and letter-bits out of the bog. The tanning agents in the iron gall ink tanned the vellum so that frequently words or letters… or letter-parts would survive when the rest of the inner manuscript did not. In general, the inner portion of the manuscript was more likely to dissolve than the outer edges, which were exposed the tanning elements of the bog, would be preserved.
After cleaning, the Psalter page fragments underwent hyper spectral scanning, which John and his team undertook in an effort to read some of the illegible areas of the manuscript. After scanning, the fragments were ready to be dried.
The process that creates vellum creates a lot of tension in the material, and that tension shows itself most dramatically when drying wet vellum…. in intense shrinking and warp. John’s talk mostly focused on the de-watering of the vellum. Using some old historical vellum flyleaves the he had laying around the lab, John recreated putrefied vellum on which to test various drying methods. He and his crew kept track of changes in color, size and flexibility. After months of testing, they decided to proceed with a solvent bath of alcohol. They needed to restrain the vellum while it dried to minimize dimensional changes. The solvent exchange took place in a vacuum sealed bag that exerted even pressure against the entire fragment. This neatly solved the problem of restraining fragile vellum.
The National Museum of Ireland has a page devoted to the Faddan More Psalter project, with the full report on the psalter freely available.
NYC’s Museum of Modern Art owns sixteen Piet Mondrian oil paintings, the most comprehensive collection in North America. From this starting point, conservator Cynthia Albertson and research scientist Ana Martins embarked on an impressive project, both in breadth and in consequence—an in-depth technical examination across all sixteen Mondrians. All examined paintings are fully documented, and the primary preservation goal is returning the artwork to the artist’s intended state. Paint instability in the artist’s later paintings will also be treated with insight from the technical examination.
The initial scope of the project focused on nondestructive analysis of MoMA’s sixteen oil paintings. As more questions arose, other collections and museum conservators were called upon to provide information on their Mondrians. Over 200 other paintings were consulted over the course of the project. Of special importance to the conservators were untreated Mondrians, as they could help answer questions about the artist’s original varnish choices and artist-modified frames. Mondrian’s technique of reworking areas of his own paintings was also under scrutiny, as it called into question whether newer paint on a canvas was his, or a restorer’s overpaint. Fortunately, the MoMA research team had a variety of technology at their disposal: X-Radiography, Reflectance Transformation Imaging, and X-ray Fluorescence (XRF) spectroscopy and XRF mapping were all tools referenced in the presentation.
The lecture discussed three paintings to provide an example of how preservation issues were addressed and how the research process revealed information on unstable paint layers in later Mondrian paintings. The paintings were Tableau no. 2 / Composition no. V (1914), Composition with Color Planes 5 (1917), and Composition C (1920), but for demonstration’s sake only the analysis of the earliest painting will be used as an example here. Tableau no. 2 / Composition no. V (1914) was on a stretcher that was too thick, wax-lined, covered in a thick, glossy varnish, and had corrosion products along the tacking edges. Research identified the corrosion as accretions from a gold frame that the artist added for an exhibition. The painting has some obviously reworked areas, distinguished by dramatic variations in texture, and a painted-over signature; these changes are visible in the technical analysis. The same research that identified the source of the corrosion also explained that Mondrian reworked and resigned the painting for the exhibition. XRF mapping of the pigments, fillers, and additives provided an early baseline of materials to compare later works to, as the paint here did not exhibit the cracking of later examples. Ultimately, the restorer’s varnish was removed to return the paint surface to its intended matte appearance, and the wax lining was mechanically separated from the canvas with a specially produced Teflon spatula. Composition no. V (1914) was then strip-lined, and re-stretched to a more appropriate-width stretcher.
It is possible to create a timeline of Mondrian’s working methods with information gleaned from the technical examination of all three paintings. His technique had evolved from an overall matte surface, to variations in varnish glossiness between painted areas. XRF analysis demonstrated a shift in his palette, with the addition of vermillion, cobalt, and cadmium red in his later works. XRF also revealed that the artist used registration lines of zinc and lead whites mixed together and used on their own. Knowing the chemical composition of Mondrian’s paint is vital to understanding the nature of the cracking media and identifying techniques to preserve it.
The underpinning of all this research is documentation. This means both accounting for un-documented or poorly documented past restorations, as well as elaborating upon existing references. Many of the MoMA paintings had minimal photographic documentation, which hinders the ability of conservators to identify changes to the work over time. The wealth of information gathered by the conservation and research team remains within the museum’s internal database, but there are plans to expand access to the project’s data. Having already worked in collaboration with many Dutch museums for access to their Mondrian collections, it’s clear to the MoMA team how a compiled database of all their research and documentation would be groundbreaking for the conservation and art history fields.
In the spring of 2013, San Franciscans were outraged to discover that a cherished Maxfield Parrish wall painting had been removed from its home in the Palace Hotel and sent to New York to be sold. Prior to auction, it was to be cleaned of the hundred-plus years of accumulated grime and accretions it had been subjected to while hanging in The Pied Piper Bar. Thus, even after the Palace Hotel had acquiesced to public sentiment and agreed to return it to San Francisco, the painting remained in New York to be treated.
Harriet Irgang Alden, of Rustin Levenson Art Conservation Associates, had experience with other Parrish wall paintings, and knew the treatment concerns that were inherent to his working methods. The artist alternated thin transparent glazes of brilliant, unmixed pigments with saturating layers of varnish. This made the removal of a restorer’s varnish on a Parrish painting a fraught process that is typically not undertaken, because of the likelihood of disrupting the original layers. The planned treatment outcome only focused on grime removal. The immediate uniqueness of this Parrish wall painting was in the details of its construction. Despite its substantial size at 5 feet by 16 feet, the Pied Piper was not painted in sections, as Parrish’s other wall paintings were. The painting appeared to have been shipped rolled from the artist’s studio to San Francisco, where a stretcher was constructed for it—possibly of redwood due to the incredible length of the members. Additionally, the back of the original canvas remained visible, and displayed a ticking pattern similar to the canvas used for an 1895 Old King Cole painting. The unlined canvas, as well as the unique stretcher, provides new material evidence of Parrish’s working methods.
Unlike previous Parrish treatments, grime removal on the Pied Piper had revealed a broken varnish layer. Apart from thick brush drips and a pockmarked appearance, there were passages of flaking, which curiously did not reveal dull, unvarnished paint beneath. Instead, beneath the discolored upper varnish there appeared to be a clear, glossy layer of a different varnish, and beneath that were the brilliant blues typical to Parrish’s paintings. FTIR analysis at the Museum of Modern Art in New York verified that there were two distinct varnishes: the crumbling upper layer was an alkyd, and the lower a decolorized shellac. Alkyds like this alcohol-acid polymer were not produced prior to the 1920’s, so they could not have been original to Parrish’s 1909 Pied Piper. The decolorized shellac was stable and was still firmly adhered to the paint beneath. Both original layers had actually been protected from UV and bar patron damage by the alkyd addition.
After an aqueous cleaning removed the grime layer, the conservators were faced with an exciting prospect: could they remove the restorer’s varnish, and in doing so, reveal a pristine Maxfield Parrish painting? Solvents would penetrate through both layers and affect the pigment. A more complex process was tested: methyl cellulose in water was applied, and removed after five to ten minutes, to soften the alkyd layer. Though in initial attempts a scalpel was used, the conservators found that the softened alkyd varnish would lift easily and safely by being pulled up with tape using the ‘Texas Strappo’ method. This technique was successful, and revealed a brilliant and unharmed original varnish layer, but it was also incredibly time consuming.
The Palace Hotel declined to extend the treatment of the Pied Piper to include a months-long varnish removal. The alkyd removal test area was toned to blend back in, the painting was varnished with Regalrez, and the Pied Piper returned home. The non-original alkyd varnish remains, still degrading, but it continues to protect the pristine painting and original varnish beneath. In the future, it will be possible to remove the new Regalrez varnish with naphtha, which does not affect the original shellac varnish. It will also be possible to remove the alkyd layer with the solvent and mechanical methods outlined in the test, and revarnish with Regalrez, and possibly a UV stabilizer. Maxfield Parrish’s vibrant original may not be fully unveiled, but until then, the beloved painting is safely on display.
Alex Carlisle presented a fascinating and detailed treatment of the pulpit in Fort Herkimer Church, German Flatts, New York (http://fortherkimerchurch.org/7.html). The church has a long history; the current structure dates to 1767, with many additions and expansion in war and peacetime. The pulpit was added in the early 19th century, and seems to be completely unique; it is made from white pine, but nothing is known about the workshop. Pulpit image: http://www.mohawkvalleymuseums.com/fortherkimerchurch.html
During a recent, major renovation of the church, white paint coating the pulpit was partially sanded off and discovered to be covering polychrome decoration. At this point, Carlisle was asked to work on the project, to remove the remaining white overpaint and preserve the original polychrome layer. At least one coat of white paint was lead-based, and very intractable; the majority of this was mechanically removed. Fortunately an older resin coating layer was present, and the lead white paint tended to cleave off at the interface.
Once the white overpaint was removed, the remaining original surfaces were consolidated and coated with a barrier layer. Losses in the polychrome ornament were inpainted to re-create the original decorative effect. So far the base and main section of the pulpit have successfully been treated; the canopy awaits funding to complete the project (keep an eye out for part 3!)
Nolley and Gillis treated a 17th century Pennsylvania German shrank which is a rare example with surviving original painted finish including faux burl wood graining and colorful decorative ornaments.
Shrank is a German word for wardrobe; many such cabinets were made in America by immigrants, using locally available woods. As with other types of furniture, these would sometimes have been faux painted to imitate a fancier wood with more elaborate carving or decoration; grain painting was a common decorative technique. Due to their utilitarian nature, original finishes on early examples seldom survive.
Cross-section analysis showed that the Chipstone shrank did have original paint, but with large areas compromised by fire damage and wear from use. This led to the initial overpainting in the early 19th century, followed by several consecutive paint treatments over the years, including an opaque, gray-blue colored casein based paint. This gray-blue layer proved to be very intractable, particularly over areas that were burned or highly worn. Cleaning solutions with chelators were able to remove the majority; agar gel was used for local cleaning around sensitive areas. Older oil-based coating layers actually acted as a resist to prevent the cleaning from going too far.
Completed with varnishing, waxing, and selective inpainting, the treatment was able to successfully expose original decoration and give a sense of the shrank’s intended appearance.
Catherine Coueignoux presented an exciting treatment of the Augustus Rex (c.1750) writing cabinet in the collection of the Victoria & Albert Museum (W.63-1977 http://collections.vam.ac.uk/item/O74665/writing-cabinet-kimmel-michael/# )
The elaborate ormolu mounts had been previously re-gilded. Before treatment were coated with a thick layer of dirt and dust over a shoe polish-like wax treatment, which was possibly added to dull the appearance of the bright new gilding. All other metal components were corroded, and the wood and marquetry had all been stripped and refinished. Curators wished the treatment to result in a bright, nearly-new appearance as it may have looked when newly restored (the previous refinishing and regilding probably occurred while owned by the Rothschild family). The Augustus Rex writing cabinet was made c.1750 for Augustus III, Elector of Saxony, possibly by Michael Kümmel, based in Dresden. The Victoria & Albert Museum acquired the cabinet in 1977.
Spotty corrosion on metal components that could not be removed was treated locally where possible. EDTA gel and BCA gels were tested but unsatisfactory- cleaning not enough, or too well. Coueignoux was able to use rottenstone to spot clean dark areas, leaving a layer of light corrosion sympathetic to surrounding areas. In some places, the corrosion spots were left untreated.
The removable ormolu mounts were cleaned using dry ice pellets, a new method for the lab. Their system uses a block of CO2 dry ice which is shaved into pellets and sprayed onto the surface of the object using an air compressor with a custom nozzle. The CO2 pellets expand on contact, providing a gentle mechanical cleaning. By moving quickly along the surface, they were able to avoid excessive cooling that would result in condensation. Acetone and a hairdryer were on hand to remove any condensation that did form. Other labs using CO2 cleaning include the Getty and the Smithsonian.
In the case of the ormolu mounts, CO2 cleaning was fast, safe and effective and removing the unwanted wax and dirt- 150 mounts were cleaned in only seven hours! Obviously this method is not appropriate for many objects and materials, but may be a convenient choice for more conservators in the future.
A problem encountered in the study of paintings is distinguishing the medium in which they were created, and delineating layers which may include different media of mixtures of media. This was the subject of a paper presented at the Research and Technical Studies session.
It is not easily possible to distinguish between oil paintings and tempera (egg-based) paintings by eye, or using many analytical methods. The authors discussed the benefits and drawbacks to three main types of analysis that are used within paintings conservation: cross-sectioning, Fourier-Transform Infrared (FTIR) spectroscopy, and thin layer chromatography (TLC). FTIR, for example, cannot distinguish between egg proteins and glue, and the results can be masked by pigments or colorants. None of these methods, as discussed, can be definitive when it comes to mixtures of media such as tempera grassa.
The author also considered the effectiveness of other common methods, such as GC/MS (Gas Chromatography – Mass Spectrometry). The main drawback to this is that results cannot be compared across different experiments if the methodology varies even slightly.
The combination of these drawbacks in common methodologies led the authors to pursue Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), a high-resolution technique that is better at separating and identifying fragments which are different but have similar masses. It also allows for the presence of specific compounds to be ‘mapped’, giving a helpful visual of layers and levels. Using this method, they were able to map for amino acids, identifying the presence of animal glue in a mixture. Practically, this was shown to differentiate between a gesso-size ground and the glue layer which was determined to have been purposefully added.
The talk concluded with a reminder that this technology, as with most, works best in conjunction with other methodologies. While this is an important point to remember, the potentials of this technique are exciting. I’m very interested to see the potential that this technique has for three-dimensional objects with multiple painted or gilded layers. I hope that someone pursues this, and that the technique is able to be harnessed across conservation disciplines.
