Chemistry of an Icon

Michelle Shulman, chair of the Chemistry Department, first became interested in the intersection of art and chemistry when she attended a one-week intensive National Science Foundation (NSF) workshop in the summer of 2006 in which Ph.D. scientists learned about the chemical composition of objects of art and how chemistry could be used to understand the nature of these objects. As a part of the many hands-on projects during the week, workshop participants created paintings from pigments and dyes. “But we weren’t given a problem to solve, an unknown,” Shulman said. “That would have thrilled me. I left that workshop wanting more.”  She deepened her knowledge while serving as a co-leader in an advanced art and chemistry workshop sponsored by the NSF in summer 2009 as well as during a 2010 sabbatical in which she analyzed a series of Indian paintings at the Victoria & Albert Museum in London. “A great experience. Really transforming.”

So, when there was a need for someone to teach chemical instrumentation in her department, Shulman decided to create challenges for her students that would include analysis of an artwork. She engaged a local artist who specializes in icons to create a fragment that she would represent to her students as a possible 12th century Russian icon.  And she built into the lab capstone project an unknown, a problem to solve: Do the components of the fragment support its likely origin?

“The interesting thing about pigments is that they represent a timeline,” Shulman explained. “For example, throughout this painting you’ll find titanium, from the titanium white pigment. If it really were a 12th century Russian icon, there would be a lot of lead, from lead white.” Titanium white wasn’t commonly used until the early 20th century.

“Of course, since I worked very closely with the artist, I know every last little bit of its composition,” she said. The students don’t. They first have to research the chemical anatomy of a Russian icon and then plan how to determine if the fragment could be what it is claimed to be.

“Keep in mind that we aren’t trying to precisely “age” the icon or prove its authenticity,” Shulman said. “We are looking for anachronisms, enough things out of place that you might question its authenticity.”

The students look for inorganic materials, like modern pigments, but also for the organic components. “Are they protein-based, like the rabbit’s glue in the base coat, or the egg-yolk used in the paint?”

Throughout the capstone project, the students know that, like art conservators, they need to learn as much as they can from the painting without damaging it or taking unnecessary samples for destructive analyses.

“Conservators have to weigh if the benefit of taking a sample is worth destroying a portion of the painting,” Shulman said. “Often, of course, they say it’s not.”

Shulman’s students use both destructive and non-destructive methods to acquire chemical information, carefully selecting samples for analysis that require destructive methods. Using a dissecting microscope and a scalpel, they take tiny samples from the damaged edge of the icon for chemical analysis.

The key non-destructive technique employs XRF—X-ray fluorescent instrumentation—that shoots X-rays at a sample, exciting the atoms in the material, which, in turn, emit X-rays in a spectrum of wavelengths characteristic of specific elements.

“There are numerous other instruments we could use to examine this and other samples,” Shulman said, like those she used at the Victoria and Albert Museum in London during her fall 2010 sabbatical. One such instrument is the Raman microscope, which allows for the non-destructive identification of pigments (i.e., Prussian blue) in the paint layer of an object. “But they’re costly and we don’t currently have the resources for them.” 

Art analysis isn’t the only approach Shulman uses to teach her students about chemical instrumentation and the nature of research. She begins the class with forensic analysis, taking her students on a field trip to meet the Alameda bomb squad. 

“The students actually collect bomb debris that contains organic explosives and extract material from it to analyze,” Shulman explained. “They do a lab on fiber and glass analysis employing a polarizing light microscope.” They also have the chance to analyze blood alcohol samples to determine if their sample donors were legally drunk. 

Shulman taught a January Term course in forensic science in which she set up very realistic crime scenes for the students to explore and analyze.  And she’s taught two other Jan Term course so far, a travel course to London on the chemistry of art restoration and conservation and a course on the chemistry of bread science.  “The first two weeks we go through a series of experiments and then they have to propose a project. For example, one group looked at how the amount of honey used in bread influences the activity of the yeast and how they could actually measure that,” she said. 

Shulman, who focused on atmospheric chemistry in her graduate study, clearly sees a broad spectrum of possibilities for teaching chemical analysis to students.  “I think of things as a merge of different disciplines,” she said.

Ultimately her aim is to design projects that help students gain confidence and competence in the collection and analysis of data.