reneewolcott – AIC Blog Archives: Conservators Converse

AIC’s 40th Annual Meeting – Angels Project, May 8: Practical Conservation at the Sandoval County Historical Society

I love Angels Projects. There is nothing precious about them. They are practical, down-to-earth conservation projects in which the rubber meets the road, and they give AIC members a chance to reach out to ordinary people who care passionately about their unique collections. On May 8, 2012, several new Angels earned their wings at the Sandoval County Historical Society, working side by side with volunteers to preserve archives, rolled maps, photographs, and oil paintings.

Sandoval County Historical Society is located in Bernalillo, New Mexico, in the home of artist Edmond DeLavy. DeLavy studied illustration at the Pratt Institute in New York, and following World War II, he moved from Maine to homestead the Bernalillo property: two and a half acres of what had been Santa Ana Pueblo lands. (The tribe is now buying back the surrounding land; they own the successful casino next door.) Before DeLavy’s death in 1989, he bequeathed his adobe home and studio to the local historical society.

Photo displays at the Sandoval County Historical Society

Its collection includes dozens of DeLavy’s original paintings and hundreds of photographs documenting the local Spanish villages and Indian pueblos, many of which have been mounted on posterboard. The historical society also collects archival documents, genealogies and family histories, bound volumes for its library, and maps. Its all-volunteer staff includes Martha Liebert, who acts as the archivist, and Dirk van Hart, who has been single-handedly digitizing the society’s photographs. Many of these photos are themselves copies of family pictures belonging to the local people, who often burn the originals after the deaths of those depicted. Often, the Sandoval County Historical Society retains the only images witnessing to the Spanish or Indian heritage of the surrounding families. The posters that illustrate this heritage travel to local schools and service organizations to educate and instill pride in today’s Sandoval County residents.

Last Tuesday, about fifteen volunteers with AIC’s Angels Project joined the society’s volunteers to begin the task of organizing and re-housing its maps, oil paintings, and archives. One team hauled the paintings from their storage closet, where they had been stored in groups in large plastic bags, and rewrapped them individually where necessary. Another team gathered the rolled maps for flattening and rehousing in a map case. A third team, which included me, gathered the society’s most-used archival documents and transferred them from acidic bankers’ boxes to new folders and polyethylene sleeves in alkaline boxes.

As is often the case with Angels Projects, we worked with few tools and a narrow assortment of supplies. We were forced to be creative, and to make efficient use of the short time we were given. The team rehousing the paintings lined them up against the walls and selected the most vulnerable images–for example, those without frames–to wrap in paper. They then returned the paintings to their storage closet, ensuring that no canvases were in danger of denting or stretching. Without a humidity chamber, the map team resorted to mechanical flattening, using stones in polyethylene sandwich bags as weights. Over the course of the morning and afternoon, they gradually unrolled and rehoused all of the society’s rolled maps, which are now stored flat in a dedicated case.

In the archives team, faced with mountains of paper, photos, and newspaper clippings, we debated about how we could be of most use. Should we start an Excel database of each folder? Each item? Should we attempt to reunite loose materials with the folders where they belonged? Where should we start? And how could we include the society’s volunteers, who were desperate to help? Eventually, we decided to begin with the most used materials, and to spend our time removing staples, paper clips, and sticky notes. We rehoused items that had been fastened together in polyethylene sleeves, and we moved sticky notes to sheets of acid-free interleaving folded around the originals. When folders were overstuffed, we subdivided them into new archival folders, and we kept records of the types of materials found in each folder.

More importantly, we sat down with the volunteers and gave them a basic overview of archival maintenance. We explained how fasteners and sticky notes can damage paper and photos in the long term, and offered suggestions for their removal and replacement. We also discussed possible options for cataloging the collection and for storing and backing up its digital images. All afternoon–after a delicious home-cooked lunch of deviled eggs, enchiladas, salads, cakes, and pies provided by the volunteers–we worked side by side to improve the housing and organization of the society’s archives.

Volunteers rehouse the Sandoval County Historical Society archives.

The day was a tremendous success, and we all left feeling that we had made a big difference. The work was a reminder that sometimes we need to set aside our conservation ideals–the clean benches, the lab coats, the high-tech gear and the high-brow jargon–for simple conversations. We need to explain what we do and why, in plain language, without condescension. We need to empower other cultural caretakers to do whatever they can for their collections. In short, we need to make colleagues and friends.

Like all Angels Projects, the work with the Sandoval County Historical Society opened a short window in which to build long-lasting connections. We helped its volunteers preserve their own cultural heritage, whether they are rehousing their collections themselves or calling a conservator for advice, guidance, or to undertake a complex treatment. Next year, be an Angel! It might be the best outreach project you’ll ever undertake.

AIC’s 40th Annual Meeting, Book and Paper Session, May 11: “New Book and Paper Conservation Products and Processes from the Heritage Science for Conservation Laboratory” by John Baty

According to John Baty, he’s got a dream job: working side by side with conservators in a book and paper lab that bridges the gap between scientific analysis and bench work. You might call it practical science, or treatment-driven analysis. In either case, Baty argues that the Heritage Science for Conservation Laboratory–part of the Department of Conservation and Preservation in the Sheridan Libraries at Johns Hopkins University–is a model the rest of us should follow. Plus, the Andrew W. Mellon Foundation-funded lab has developed some cool toys we can use in our own paper-based research.

For Baty, the collaboration between chemists and conservators is key. (How’s that for alliteration?) This meeting of the minds has led the HSC Lab from fundamental research into the degradation mechanisms for cellulose to the production of tools that can help other conservators and conservation scientists in their work–particularly if they are engaged in studies that make use of accelerated aging. During his talk, Baty introduced three of these tools and the data that support their usefulness.

The first technology he discussed was the range of common-ion effect buffers that can be used to maintain a given pH in paper. These buffers, which take advantage of the equilibrium between a weak acid and its conjugate base, establish a narrow pH range that resists change, even after accelerated aging. Research at the HSC suggests that phosphate buffers added to paper remain effective after 42 days of accelerated aging, even at higher temperatures. In aging studies, these buffers can be used to minimize the number of variables acting on the test papers as they age. In theory, such buffers could also be used to maintain a pH range that would slow the deterioration of ir0n-gall ink or prevent color shifts in pH-sensitive dyes and pigments.

The HSC has also developed a new vessel for accelerated aging, after noticing hairline cracks and other failures in the vessels currently in use. The new closed tube, which features a glass-on-glass seal, was developed in collaboration with conservator Bill Minter. It can withstand high pressures without losing moisture, and because it has no gaskets, its contents cannot be contaminated by residual polymer chemistry or offgassing from faulty seals.

Finally, Baty introduced a calibration kit that will allow scientists and conservators to calibrate their X-Ray Fluorescence (XRF) or Near Infrared (NIR) spectrometers for nondestructive paper analysis. The kit contains paper targets uniformly coated with specific salt concentrations.

AIC’s 40th Annual Meeting, Book and Paper Session, May 11: “Preservation of Cultural Heritage: The Restoration of the Globe in Relief” by Maria Gabriela Mayoni

In the last BPG session of this year’s AIC meeting, “global conservation” took on a whole new meaning. Maria Gabriela Mayoni, a conservator of cultural heritage from the Colegio Nacional de Buenos Aires, Argentina, delivered a lavishly illustrated lecture concerning the conservation of a papier-mache globe and its support. This globe, manufactured in Germany in 1850 and bearing site labels in French, belongs to the Department of Geography of the Colegio Nacional and illustrates the European influence on Argentina during the nineteenth century–a period of nation-building and economic development. At some point in the past, the rare globe was seriously damaged in an accident: a large section was crushed, a portion of the papier-mache sphere was lost, and the support rings were deformed. The varnish coating the globe had also darkened and discolored, making the labels and land masses hard to read. The area representing Argentina had been overpainted, perhaps to keep up with changing geopolitical boundaries.

Mayoni described the complex structure of the globe, which included a papier-mache sphere with outer layers of cast composite, paper labels, paint, and varnish. This globe was mounted on a wooden axis, fitted with metallic rings, and placed on a stand made of iron and wood. All of these elements were addressed during the comprehensive conservation treatment of the globe.

Prior to beginning treatment, Mayoni and her colleagues analyzed the materials present on the globe with FTIR, and the results were consistent with an oil and natural resin varnish. This was cleaned with a mixture of water and ethanol, which was applied carefully to avoid disturbing the water-sensitive inks on the printed labels. After the varnish had been reduced, the conservators split the globe into its two original halves. Inside, they discovered labels containing information about the globe’s manufacture, including a date decades earlier than they had anticipated. The crushed portions of the globe were humidified and reshaped, and the losses were filled with a vinyl acetate adhesive and long-fibered paper. After the sphere had been mended from the inside, the two halves were reassembled, and the join was reinforced with cotton fibers. A combination of animal glue and calcium carbonate was used to fill the losses in the topographical relief. The deformed metal rings were reshaped, polished, and given a protective coating. The wooden elements of the stand were also reshaped as necessary to return the globe to usefulness.

Mayoni noted that the varnish selected during treatment will have to be replaced in a second conservation campaign. The reassembled sphere was varnished with a soft synthetic resin soluble in white spirits. Harder, solvent-soluble resins were rejected because the solvents used to reverse them would have affected the inks on the labels. However, the soft resin has become yellow and grimy since it was applied. After further testing, it will be replaced with something more durable and colorfast.

The globe is once more in use in the Geography Department of the Colegio Nacional de Buenos Aires, where the students and faculty learn the importance of preserving their cultural heritage as well as their place on the map.

AIC’s 40th Annual Meeting, Book and Paper Session, May 11: “Case Study: Examination and Analysis of a Mesoamerican Deerskin Map” by Ted Stanley

Ted Stanley wrapped up the Book and Paper Group sessions on Friday, May 11, with his presentation about the authentication and analysis of a 16th-century Mesoamerican map belonging to Princeton University Library. The map was believed to have a c. 1550 creation date, and depicts a portion of the central valley of Mexico at the time of the European conquest. Stanley attempted to determine the authenticity of the deerskin map through noninvasive analysis techniques, including light microscopy, UV-induced visible fluorescence, UV-VIS spectroscopy, and FTIR.

The map, which features black, blue, green, red, and yellow colorants on a leather support, depicts the upheaval in Mexico at the time of European conquest. Hernan Cortes famously invaded Mexico in 1519. The priests who followed in his train destroyed Maya and Aztec maps and codices, and Spanish conquistadors killed many indigenous people, especially those who resisted conversion to Christianity. In one of the map’s illustrations, priests preach to native noblemen, perhaps with limited success: one priest is shaking an Aztec listener so violently that blood flies from his nose. The map also illustrates roads, waterways, villages, agave plantations, and irrigation systems, accompanied by Aztec glyphs or pictograms and their Spanish translations, or glosses. It captures the meeting of the Old and New Worlds, with depictions of Aztec warriors, Spanish priests, Aztec shrine altars, and colonial Spanish villages. But is it authentic?

According to Stanley, the hide support was roughly scraped as part of the tanning process; he is still investigating how the Aztecs may have treated the skin to preserve it. Large, circular voids in the leather appear to be the natural result of abscesses in the animal’s skin rather than later damage. The map was previously folded and has prominent creases as a result. Its pigments are stable, with minor abrasion, and the map displays some liquid staining and minor losses along the edges.

Since no follicle pattern could be determined using light microscopy, Stanley compared the collagen fibers present in the map’s support with those of a known deerskin, and found they had comparable length and width. He also examined the map’s colorants and found evidence for both yellow and orange dyes, which were absorbed into the collagen fibers, and for blue, green, and black pigments, which were deposited on the leather surface.

Stanley then used UV fluorescence for general pigment identification, comparing the fluorescence of the map’s colorants to the fluorescence of Kremer pigment samples. Based on his observations, he tentatively identified the red colorant as cochineal, the yellow-orange as gamboge, and the blue as Maya blue, a combination of indigo and palygorskite clay. While cochineal and Maya blue are both associated with traditional Aztec culture, the gamboge was a surprise, since it is normally associated with Southeast Asia. In addition, the fluorescence of the green pigment did not match that of any Kremer samples. UV-VIS spectroscopy of the map’s colorants reinforced Stanley’s original pigment identifications, but the green remained a mystery.

Finally, Stanley turned to Fourier-Transform Infrared Spectroscopy using Attenuated Total Reflectance (FTIR-ATR) for more definitive pigment identification. Once the bands for the hide support had been subtracted, the spectrum for the red dye displayed the characteristic absorption band for carminic acid, confirming the presence of cochineal. The yellow-orange dye produced an absorption band for gambogic acid. Stanley theorizes that the gamboge present in the map is actually American gamboge, a resin that is chemically identical to Asian gamboge but originates in a Mexican plant. Both the blue and green pigments produced spectra containing absorption bands for indigo and palygorskite clays, suggesting that they are Maya blue and Maya green: the same pigment/dye complex at lower and higher pH levels, respectively. The black pigment produced absorption bands for calcium and phosphate, indicating the use of bone black.

Because all of this evidence points to the use of pigments and dyes known to have been used during the early colonial period, Stanley has determined that the map is likely to be contemporary with the European conquest of Mexico. However, the colorants, the skin, and the tanning process all provide tantalizing opportunities for further research. Could the green colorant be Maya blue in combination with a yellow dye? Is the leather in fact deerskin? How was it tanned? Finding the answers to these questions could shed more light on the map’s authenticity, and illuminate a period of dramatic historical change with even more accuracy.