AIC's 47th Annual Meeting

Silver stain luster and enameling of glass from the Syro-Palestine area is known to be critical for understanding the development of silver staining techniques. However, given the material complexity of objects possessing these features, they can be challenging to characterize. Key features must be understood at the nanometer (silver nanoparticles), micrometer (nanoparticle distribution and luster/enamel thickness), and bulk (base glass composition) scales. Consequently, there are relatively few studies of such breadth. This paper details a technical study that combines nano, micro, and macro material imaging techniques, as well as bulk quantitative analysis to elucidate the nature of a glass carchesium with hand-painted enamel decoration that was suspected to be a 1st c. Roman vessel at the time of acquisition. A variety of imaging techniques were combined with bulk analysis to characterize the object, including transmission electron microscopy (TEM), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), imaging and bulk XRF measurements, strontium isotope analysis by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The carchesium was purchased in 1922 from New York dealer Fahim Kouchakji by Mrs. William H. Moore, who donated it to the Yale University Art Gallery in 1955. At the time of purchase the object was suspected to be 1st century Roman based on form, blue glass body, olive branch decorative elements, and splash glass decorative elements. The object, which recently underwent conservation treatment and was studied during that time, is significantly corroded in a manner consistent with a burial environment. Microscopic examination revealed that the decorative material was inset in the glass, with a layered structure consisting of alternating orange-brown and blue-green bands. Initial XRF point- and imaging-based measurements showed that the decorative enameling contained silver, and no other element that could easily explain the coloring. SEM/EDS and TEM measurements revealed the presence of silver nanoparticles and characterized their depth-dependent size and shape. Strontium isotope analysis suggested the lime was derived from a calcareous sand deposit rather than limestone. Quantitative XRF and ICP-OES measurements reveal a soda-lime base glass and an overall composition more consistent with Roman glass made in the Syro-Palestine area during the fourth to eight centuries. Work is ongoing to characterize the glass in the enamel layers quantitatively and model light-matter interactions with the nanoparticles to confirm they are responsible for the observed coloring. Additional future efforts will focus on the location of potentially similar objects in other collections.