In 2020, chemistry graduate student Erin Birdsall received a unique opportunity—to live the life of a conservation chemist as an intern at the Indianapolis Museum of Art (IMA). Birdsall spent the summer of 2020 working on an icon of High Renaissance art: The Miraculous Draught of Fishes, a reproduction (ca. 1630) of one of ten tapestries in Raphael’s Acts of the Apostles series.
The museum acquired the 400-year-old tapestry in 2016 and received funding from a Bank of America art conservation grant to study and restore the work of art, which had suffered exposure to light and gravity during years of exhibition. Birdsall learned about the internship opportunity when Gregory Smith, a senior scientist at the IMA, visited the UW–Madison chemistry department and mentioned that the museum was on the lookout for interns.
“I’ve always been interested in art history, and when I was an undergrad at Middlebury College, I learned that you could work as a scientist in an art museum, so that career path was in the back of my mind,” Birdsall says.
The Miraculous Draught of Fishes depicts a story regarded as a founding moment in Christianity: Jesus tells Peter to cast his net into the water, after which Peter and his fellow apostles make a miraculous catch of fish. The original Acts of the Apostles tapestries were hung in the Sistine Chapel.
Birdsall helped perform state-of-the-art dye analyses on the work. As an initial step of the restoration process, dye analyses explore different tapestry samples to understand what dyes and mordants (inorganic salts that help dyes bind to fibers) were used to make a tapestry and to identify colors and fibers that might be used for contemporary repairs.
“The data will tell you if there’s iron in the dye, or aluminum, or nickel, and then you’ll get these mass spectra that are essentially fingerprints. Because dye molecules are relatively well-characterized, you could say that a blue color was created with an indigo dye, for example,” says Birdsall. “That allows you to learn what common dyes and mordants were being used at the time the tapestry was woven.”
Birdsall used three techniques: gas chromatography mass spectrometry (GCMS), x-ray fluorescence and liquid chromatography mass spectrometry (LCMS). Each technique generates spectra that provide information about components in the dyes at specific locations on a tapestry.
Birdsall’s data helped identify dyes from several samples that were not natural to the early 1600s, suggesting previous repairs. And her comparative analyses demonstrated that equivalent results can be obtained using both GCMS and LCMS, hopefully making similar studies available to museums that might only have a GCMS system. After Birdsall finished her internship, the tapestry underwent restoration in Europe and is now actively installed in the IMA’s galleries.
After defending her PhD this spring, Birdsall accepted a postdoctoral fellowship at the Smithsonian Institution. There, she is working on a preventive conservation project with the Museum Conservation Institute and the National Museum of the American Indian.
“This postdoc will help me finish my training in the field of heritage science [also known as conservation science],” Birdsall says. “The internship at IMA really cemented what I want to do in my career.”
Funding for Birdsall’s internship was made possible through the Biotechnology Training Program (BTP), a National Institutes of Health program based in the College of Agricultural and Life Sciences (CALS).
