(by Adam Ring, Chemistry Team)
This was a busy week for the SCIART program with two opportunities to gain on-site experience in the fields of art conservation and conservation science. On Tuesday, the chemistry group were invited to shadow Dr. Glenn Gates, a conservation scientist at the Walters Art Museum, and assisted him with the projects he was working on.
At the Walters, we were introduced to an Indian miniature painting recently acquired for the collection. The image depicted the goddess Parvati holding the infant Ganesha, seated on a platform, and elaborately adorned with jewelry. There appeared to be metallic inlays within their jewelry and along the edges of the platform. The work was dated to the 19th century. The overall goal was to narrow that range by determining the various pigments and metals used in its construction. Since two members of the biology group would be shadowing Dr. Gates the following day, our group decided to focus on the metals embedded in the paper.
Assisted by Elisabetta Polidori, a book and paper conservator at the Walters, the first step involved a thorough analysis by light microscopy to see what we could determine visually. The tiny metal tokens embedded in Parvati’s jewelry and along the edges of the platform alternated in light and dark color.
Using X-Ray Fluorescence (XRF), we were able to gather some intriguing information about the metals. The lightly colored tokens showed a large proportion of copper with some silver. We could infer that copper tokens were electroplated with a very thin layer of silver in this case. The darker tokens had a high proportion of silver to copper, and lead appeared to be within a matrix. This was unexpected because an inner layer of lead would interfere with silver electroplating.
Taking a closer look at the metals under the microscope, we could see minimal amounts of red and green colorants at the edges of the metal inlays. We learned that depictions of rubies, emeralds, and diamonds were common in Indian miniatures, so we could infer that these metals were likely covered in red and green glazes to mimic these gems. This case study was a fascinating break from our daily research and demonstrated that in practice, answering one question about a work may introduce many more questions.
On Thursday, the chemistry, biology, and engineering groups visited the Winterthur Conservation Institute and Museum. The visit began with a session lead by Debbie Norris, chair and professor of art conservation, who specializes in photography, who taught us about different types of photographs from the original tintypes to present-day digital photos. She also discussed various aspects of Winterthur’s conservation graduate program including admissions, the steps one takes within the program, and choosing a conservation focus.
Afterwards, we met with the conservation scientists at Winterthur who discussed some of the projects going on including analysis of silver in the collection and analyzing southeast Asian lacquers using different chromatographic techniques. The director of conservation, Joy Gardiner, then gave us a tour of the various conservation labs including paper, objects, wood, textiles, books, and paintings. Ending the day, we had the time to explore the Treasures on Trial exhibition of forgeries at the Winterthur Museum. In the exhibition, it was particularly interesting to see how different techniques we’ve been using, including Raman and FTIR spectroscopy, could be used to authenticate or convict a work of art.