Joan Walker, Ph.D

As a high school student, Joan Walker was drawn to two subjects that helped her understand the world. Chemistry revealed how materials behaved and interacted. Art history, meanwhile, offered insights into historical movements and culture.

When Walker majored in chemistry and art history at Washington University in St. Louis, she didn’t know how she would pull these passions into a career. She only knew that she wanted both chemistry and art in her life. After completing a PhD in Inorganic/Materials Chemistry at Indiana University, Bloomington, Walker landed a job that made that dream a reality.

Walker is a conservation scientist at the National Gallery of Art in Washington, DC. She uses techniques like X-ray fluorescence and vibrational spectroscopy to study many art forms, from paintings to chalices. Her analyses help the museum understand which materials the artists used and how best to repair or protect the pieces. It’s very satisfying to later see those works hanging on gallery walls, says Walker. 

What was your first job out of college?

I was a conservation technician at the Indiana Historical Society in Indianapolis. I worked in a paper conservation lab, so I would help protect and repair items like books, letters, and posters. If a letter was crumpled, for example, I could use water vapor to relax the folds so I could flatten the brittle paper without breaking it. I especially liked working with handwritten letters because they are such a personal connection to history.

Why did you leave this job to pursue a PhD in inorganic/materials chemistry?

I loved that job. But I realized that I wasn't going to grow in that position as much as I wanted to professionally. I asked the senior conservators on staff if they had any career advice. They connected me with other conservators as well as conservation scientists at different institutions. It was then that I learned that a conservation scientist uses chemistry to help a conservator make decisions about the best way to restore, display, or store a piece. My conservator colleagues wanted to know more about the chemical composition of the materials they worked with. I thought, ‘If I become a really good chemist, I could give them that information.’

How did you find your job at the National Gallery of Art?

As a PhD student, I worked with metallic nanoparticles, particularly gold and iron oxide, to understand their interactions with protein networks for nanomedicine applications. As I was wrapping up my PhD, I heard that a grant-funded position in photograph conservation had opened here at the National Gallery. For a lot of historic photographic processes, the image is actually formed by metallic nanoparticles in a protein matrix. So my PhD experience just happened to be directly applicable.

How do you support conservators?

I work with a team of conservators who have highly trained eyes. Even without my analyses, they often have a sense of what artistic materials were used to create a piece. I always say to conservators, ‘What can I tell you that your eyes aren't telling you?’

Pinpointing the media used in a piece helps conservators better understand the artist’s artistic choices, as well as when and where the artist may have been working. Conservators also need to know the material properties of a piece so they can properly store or restore it. For example, if they have trouble removing a yellowed varnish from a painting, I help by determining the varnish’s chemical composition and offer advice on which solvent would safely remove it.

What sorts of instruments do you use?

The challenge is always how to get the most information in the least invasive way. I often use external reflectance Fourier transform infrared (FTIR) spectroscopy, which allows me to keep my spectrometer about 1.5 cm from the surface. Using FTIR and other techniques, I identified a particular blue colored pencil that was used by photographer James Van Der Zee to color a silver gelatin print in the 1950s. That blue pigment hadn’t been noted before for that period.

I use many other instruments too. To identify the gemstones on an ancient chalice, for example, I used Raman spectroscopy, which is great for identifying crystal structures.

What advice do you have for others considering a career in conservation science?

Know that it’s a small field. I chose a traditional chemistry PhD program rather than one with a conservation focus so I could keep my options open in case I couldn’t find a job in conservation science.

But also know that there are many paths to conservation science. I have a lot of colleagues with degrees in physical chemistry who only learned about conservation science at the post-doc level or later. There are also ways to work with cultural heritage materials even outside of a museum role. We often collaborate with universities or national laboratories. So my advice is to not get too wedded to one path.

This profile has been edited for length and clarity. The opinions expressed in this interview are the author's own and do not necessarily reflect the view of their employer or the American Chemical Society.