Historical lead glass in museum collections: determination of the composition by a portable X-ray fluorescence analyzer

Abstract

A method for the determination of the glass composition in the systems PbO – SiO2 and K2O – PbO – SiO2 with different additives present both in historical and modern art glass is considered. Development of a non-destructive method for determining the glass composition in conditions of museum storage is an important goal for museum practice. We propose a method for determining the composition of those glasses using a portable X-ray fluorescence analyzer (XRF). To select the optimal software suitable for measurements, we have synthesized a number of standard glass samples with the composition determined by ICP-AES. A glass sample of was dissolved in an autoclave in a mixture of nitric, hydrofluoric, and perchloric acids. The lead content in standard samples was simultaneously determined gravimetrically after fusion of the sample with sodium carbonate. Using XRF measurements of standard samples we development of a method for determination of the glass composition with an accuracy sufficient to assign the glass to one of the groups of historical glasses. The results obtained can be used for attribution of lead glass products. The content of potassium oxide in historical samples was estimated by XRF method using two independent programs with subsequent averaging of the data obtained. When using our method, the error of potassium, silicon and lead determination does not exceed 10%, which is sufficient for a museum description and attribution of an item. The developed procedure was tested in analysis of the items from the collection of the State Museum of Ceramics («Kuskovo Estate of the 18th century»).