When looking at a historic work of art, does the word chemistry come to mind? That’s right: chemistry even plays a role in art. Art historians rely on science for accurate historical information regarding works of art.
According to J. Davy in The Collected Works of Sir Humphrey Davy, the marriage of science and art dates back to 1818, when Sir Humphrey Davy chemically analyzed paints from the ancient ruins of Pompeii.
Our department conducted a study on pigment analysis in our own backyard, a sculpture housed in the David Owsley Museum of Art. A spectroscopic study of paints from a 15th century sculpture depicting Saint Wolfgang was performed by faculty member Patricia Lang and her students.
Infrared spectra on minute paint samples were obtained, and the spectra were compared to reference spectra of known art pigments and materials. In addition, energy dispersive x-ray spectra were obtained using a scanning electron microscope. The x-ray spectra were used to support the infrared results and, in some cases, allowed for the identification of materials which have infrared absorptions below the detector range or which are infrared inactive.
The combined spectral data on the paints, which were layered in several places on the sculpture, allowed us to obtain a detailed description of Saint Wolfgang's different appearances throughout the past 300 years. Although many of the pigments found are relatively modern, the first application of paint is composed of materials consistent with the sculpture's medieval date.
One of the most interesting findings is the presence of an organic red pigment derived from the lac insect, the use of which dates back to medieval times in Europe.