By Caroline Roberts, Conservator
Suzanne and I are excited to announce a new addition to our lab: a handheld X-ray fluorescence (XRF) spectrometer. We were able to acquire this instrument with the help of the NEH-sponsored Research and Development grant we received this year. This nifty-looking handheld device—which, to me, resembles something out of an original Star Trek episode—is engineered to generate a powerful X-ray beam. The X-rays are directed onto an object, where they are absorbed by atoms that make up the pigment particles in an ancient paint layer. This initiates a phenomenon called the “photoelectric effect” which results in a release of photons from the atom. These photons have quantifiable energy levels that are unique to specific chemical elements, such as iron, copper, lead, mercury, or arsenic. The XRF device can detect these photons as they leave the object, and convert this information into a graph that we can read. All of this can be done without removing a paint sample from the artifact.
We’ll use the XRF unit, along with our lab’s multispectral imaging kit and polarized light microscope, to identify pigments that were used on artifacts at the Kelsey, providing us with materials-based evidence of what artists were using to decorate objects and structures in the ancient world. For the NEH grant, we’ll be focusing our investigative efforts on the collections we have from Karanis and Terenouthis. We’re especially interested in learning which pigments people were using to paint artifacts in Roman Egypt, since there isn’t as much data from this later period as there is from earlier parts of Egypt’s history.
