Synthesizing lead antimonate in ancient and modern opaque glass

Abstract

Through the study of lead antimonate based opacifiers in three opaque glass productions—Egyptian glass of the 18th dynasty (1570–1292 BC), Roman mosaic tesserae and beads from Aquilea and Rome (2nd c. BC–5th c. AD) and Nevers lampworking glass figures 18th c. AD)—this paper shows the evolution of lead antimonate production during different periods of History. We also show the necessity of using systematic micro-chemical analyses, with both high spatial and high energy resolution techniques to investigate these types of materials. The synchrotron-based μ-XANES measurements combined with the microstructure observations (SEM and TEM), the chemical and structural analyses (EDX, WDS, μ-Raman), is the first step to getting information on the raw materials used and the technological processes employed to produce lead antimonate. The heterogeneity from one sample to another but also within the same sample, and even further within a single crystal aggregate clearly shows that a production cannot be unambiguously associated to a single chemical composition. However, differences between the three productions are clearly highlighted and hypotheses about glass manufacturing are proposed.