Teresa Duff presented the conclusion of a twenty-year, three-phased conservation project by the University of Pennsylvania Graduate Program in Historic Preservation at the Trinity Burial Ground in Pittsburgh, PA. The first phase, begun in 1990, entailed a condition survey and pilot testing program for the conservation of grave markers in the cemetery. In 2000, students from the University of Pennsylvania performed the second phase of testing, and in 2007-2008, Duff and her colleagues began Phase 3, which was in conjunction with a landscape renewal by Andropogon.
Duff explained that the site was a Native American burial ground that was adopted by white settlers in 1779. In 1822 the first church was erected on the site, and the current Trinity Cathedral was constructed in 1872. The grounds contain 155 stones along with burial-marker fragments. Duff and her colleagues mapped the site and numbered each plot, and created color-coded layers for conditions, treatments and the history of markers. They built a site-specific treatment platform for the on-site conservation of markers, and completed the conservation treatments begun in 2000. Treatments included cleaning and removal of biological growth, epoxy repairs for blind delamination and cracks, pinning with fiberglass pins, carbon fiber strap reinforcement on the back of some markers, excavation and resetting of partially buried or at-risk markers, and the burial of markers who had lost their material integrity. Fragments were displayed on the exterior walls of the church.
The author provided detailed information about treatments and products, but I would have liked to have learned more about the history of the site, the types of stones and carving represented in the burial ground, and the rationale behind some of the treatments. There were many questions following the talk about the landscape renewal by Andropogon, particularly the native grass they selected which does not need to be mowed. It was a well-organized presentation with good visuals and detailed information.
Amelia Millar from the Clemson University/College of Charleston Program in Historic Preservation, and Stéphanie A. Cretté from the Clemson Conservation Center presented a two-part paper on a graduate-level project at Fort Moultrie National Monument near Charleston, SC. Millar presented the student portion of the work, while Cretté presented the analytical research.
The project entailed a survey of metals in a portion of the Fort Moultrie site, owned by the National Park Service. Students from the Clemson University/College of Charleston program performed a survey of all existing metals, both architectural metals and the metal objects on site, and assessed the condition of the metals. They took paint samples to determine the chemical composition of the paint so that NPS can develop a strategy to safely remove any lead-containing paint while preserving the metal substrates. The students did most of the field work and tested paint-removal methods, then collaborated with scientists from the Clemson Conservation Center on SEM-EDS and Raman analysis of the paints. Most of the scientific portion of the presentation was about the analytical techniques and why they were used for this application.
The paper was interesting, but I would have liked to have learned more about the researchers’ findings and the various treatment recommendations put forward by the students. It would have also been interesting to learn whether the NPS has implemented or plans to implement any of the student recommendations. Nevertheless, it was a good collaborative project that seems to have benefited the students and scientists alike.
Jason Church from NCPTT presented a useful paper on commercially available rust converters. He explained that rust converters are a chemical treatment that converts iron oxide into a more stable product, though this product varies depending on the chemical composition of the rust converter. Church and his colleagues started with the 1995 Canadian Conservation Institute study of rust converters, but found most of the products to have been discontinued or available in new formulations. This led the team to perform their own experiment.
Church et al., selected four commercial products of varying chemical composition: Ospho (phosphoric acid base), Rust-oleum Rust Reformer (tannic acid base), Corroseal (gallic acid base) and RCx427 (oxalic acid base). The four commercial products were selected on the grounds that these products were readily available, were top sellers, and could be purchased in sufficiently small quantities so as to be accessible to homeowners or for small conservation projects. Church and his colleagues also tested the CCI-recommended custom formulation of tannic and phosphoric acid, which several objects conservators they polled still claim to use. NCPTT staff tested the five rust converters on new A36 carbon steel that was naturally weathered. They subjected each of the test samples to artificial weathering and measured the samples for color changes and active corrosion every 250 hours for 1000 hours total. They found that the Rust-oleum product had the least color change and most stable surface of the five products tested, though the efficacy of each product tested was quite varied. Church mentioned that their testing is not complete. They continue to push the Rust-oleum product to metal failure through extended artificial weathering, and will also test the new aerosol version of that product. They also plan to perform outdoor accelerated weathering tests on the five products.
The presentation was interesting and informative, as is characteristic of studies done by NCPTT. I like that their experiments are developed for conservators, but the results are accessible to anyone. The information presented in this talk will surely broaden the body of knowledge for architecture and objects conservators and will be useful for homeowners and maintenance workers. Following the talk, moderator Patty Miller recommended that they eventually expand their testing scope to include conservation-grade products and less readily available materials. I concur, and I would encourage Church and his colleagues to publish their findings.
In the summer of 2009, Kirsten Travers and LeeAnn Barnes Gordon performed documentation and conservation treatments on the ceiling of the Turkish Room in Doris Duke’s Shangri La estate in Hawaii. The ceiling was originally commissioned in 1797 for the Quwwatli family reception room in their home in Damascus, Syria, and was made using a technique called adjami. The author provided a brief but thorough explanation of the traditional material, which, if I am correct, is made by nailing together thin slats of wood, filling gaps and holes with fiber, applying raised gesso ornament followed by layers of metal foil, tinted glazes and paint. The ceiling was removed from its original location in the 1920s and spent decades in storage. Doris Duke, a devotee of Islamic art and artifacts, purchased the ceiling in 1976 and installed it in her Hawaiian home in 1979, mislabeling it the Turkish Room. By 2009, the ceiling colors were dull and the adjami was deteriorated.
The author and her colleague performed conservation treatments during their summer workshop while students in the Winterthur/University of Delaware Program in Art Conservation. While Travers breezed through her discussion of the treatments, which included injection adhesives and brush-applied consolidants, the real subject of her talk was the analysis of 50 finish samples from the ceiling. She and her colleagues at Winterthur/University of Delaware tested the samples using eight different analytical techniques, including cross-section analysis, fluorochrome staining, PLM, XRF, SEM-EDS, FTIR, Raman and GC-MS. The author described in detail her findings, particularly the blue, pink and green layers, as well as the varnish and tinted glaze layers.
While the author’s presentation was packed with information, she presented it in a clear and well organized manner. She distilled a large amount of complex information into an easily understood whole. This was my favorite talk of the ASG session, which was strong on its own. (Though perhaps I am biased, as I also perform paint investigations.) I only wish that the author had had a full hour so that she could explain her subject in greater detail. I would encourage the author to publish her findings.
Laura Buchner and Chris Gembinski gave a fascinating presentation on the conservation of dalle de verre glass panels at the New York Hall of Science, a building erected for the 1964 World’s Fair. Unlike many buildings erected for world’s fairs, the New York Hall of Science was always meant to be a permanent structure. The Great Hall is a 90-feet high ribbon-like structure of dalle de verre glass panels. The exhibition during the 1964 World’s Fair, “Rendezvous in Space”, made use of the deep cobalt blue dalles, highlighted by bits of ruby, green and gold, which give the interior the appearance of stepping into the cosmos.
The authors presented a brief description of how dalle de verre panels were made, both for this building and for typical buildings of the era. According to the authors, 1964 was a transition period when Willet Studios, a manufacturer of dalle de verre panels, began switching from the poured concrete panels used at the Great Hall, to an epoxy matrix.
In 2005, BCA began restoring the Great Hall. The goals of the project were to preserve the “experience of the building” and to address most of the deterioration and moisture-infiltration issues related to the building, but it was acknowledged by all parties involved that it would be impossible to cure all of the moisture-related problems due to the nature of original construction materials. The authors explained how they treated the typical conditions–cracks, erosion of the matrix, spalls of the concrete matrix, cracked glass, biological growth, and exposed reinforcement mesh. They replaced several panels with new dalle de verre set in an epoxy matrix, and rearranged some existing panels to minimize differences in light transmission between new and old units. They repaired cracks by injection and surface-application methods, and used a consolidant and water-repellant to reduce further deterioration of the panels. They also used a migrating corrosion inhibitor to reduce corrosion of rebar in the concrete grid.
The presentation was clear, informative, and well organized, and the conservation work looks expertly performed. I enjoyed learning about dalle de verre, as I was not familiar with it prior to the talk. I especially appreciated the authors’ willingness to share their experience using specific products, and the steps they took to maximize the efficacy of these products.