Conservation at the BMA: XFR Scanner

/ Caring for Art

As stewards of one of the most diverse collections of art in the Southeast, the Birmingham Museum of Art has a duty to ensure each work of art is properly cared for. Representing 5,000 years of global civilization, the Museum’s collection of more than 26,000 objects serves as the cornerstone for hundreds of free lectures, programs, and workshops each year. A highly technical process blending both art and science, art conservation involves researching and assessing the needs of the works of art, implementing preventative treatments, repairing damaged or deteriorating objects, and ultimately ensuring the pieces in our collection remain intact and accessible for generations to come.

Technological advances have been integral in addressing one of the greatest challenges of art conservation: correctly and safely identifying the composite materials of a given work of art. In keeping with the latest technology, the Museum’s Conservation Department was recently awarded a grant from the Susan Mott Webb Charitable Trust to purchase a portable XRF (x-ray fluorescence) scanner. The XRF device uses non-destructive, elemental analysis to examine works of art, quickly providing data regarding its elemental composition so as to ascertain authenticity, fabrication technology, and provenance, as well as alerting the user to the presence of dangerous heavy metals, ensuring the personal protection and safety of Museum personnel who handle objects.

The Museum’s XRF scanner has already produced incredibly useful information. Some results are fairly benign—such as confirming the proprietary recipe for jasperware you’d expect to find in a piece of Wedgwood or determining the metal leaf on a 19th-century frame is made of copper, not gold, as previously thought—while other scans have alerted to the presence of toxic heavy metals, such as arsenic and lead. For example, one of our Native American headdresses tested positive for the presence of arsenic, while a Lonnie Holley sand sculpture suspected of containing hazardous materials was found to have none, only sulphur. Going forward, this technology will directly impact our ability to study, conserve, and further preserve our collection of paintings, Wedgwood ceramics, European porcelain, and Asian ceramics.

Deep Dive: How it Works

The Bruker Corporation XRF (X-ray fluorescence) analyzers have quickly become the industry standard for

investigatory art conservation. During the examination process, the XRF analyzer uses X-rays to displace electrons from their atomic orbital positions, releasing bursts of energy characteristic of a specific element. The sample is bombarded with X-rays, which excites the sample to generate X-ray fluorescence. The X-rays “shoot” individual electrons out of the atoms of the elements, primarily out of the inner atomic shells K and L. The resulting vacancies are filled up again by electrons from higher energy shells. The excess energy of these electrons is then emitted in the form of X-ray fluorescence radiation. This radiation is characteristic for each element like a fingerprint and independent of the atom’s chemical bond. The intensity of the radiation is proportional to the concentration of the element in the sample. This release of energy is then recorded by the XRF, which in turn categorizes the energies and provides an analytical reading. With training on use and analysis, the conservator is then able to make conclusions about the work of art, its origin, composition, and much more.