Melting Process and Viscosity of Bohemian Historical Glasses Studied on Model Glasses

Abstract

Analyzing the chemical composition of archaeological glasses can provide an insight into their provenance and raw materials used in their making. However, to the authors’ knowledge, the historical production process itself and melting characteristics of the glasses have not yet been extensively investigated. The main focus of this paper is to describe the melting process of three main types of Bohemian historical glasses: Gothic (14th–1st half of 16th c.); Renaissance (16th–17th c.); and Baroque (end of 17th–18th c.). The model glasses were prepared from natural raw materials and processes that take place during melting were investigated using optical microscopy, SEM-EDS, XRD, and DTA-TG methods. Furthermore, the viscosity of model glasses and thermal dilatation was measured and used to calculate the reference viscosity points. The results illustrate the complexity of historical glass melting, as well as the technological progress between different periods.