The Bohemian historical glasses have been neglected and have not been in focus of Archaeometric studies so far. Potassium-calcium wood ash glasses, produced in Bohemia and Moravia, from the beginning of the 14th century to the first half of the 18th century, are chemically different from the glasses produced in the same period in Western Europe. There are no written sources for glass batch recipes for Gothic (14th–1st half of 16th c.) and Renaissance (16th–17th c.) glass, while there are only few for the Baroque (end of 17th–18th c.) glass recipes. Systematically investigating the chemical composition and typology of archaeological glasses, we have chosen to reconstruct the glass recipes of potassium-calcium glasses from the three periods. In this study, the glass recipes (the ratio of the raw materials) were calculated based on the chemical composition of the historical glasses studied by X-Ray Fluorescence (XRF) and Scanning Electron Microscopy/Energy Dispersive System (SEM/EDS). The composition of the authentic natural raw materials was studied by XRF and X-Ray Diffraction (XRD): sand or quartz pebbles, beech ash and potash, limestone, NaCl, and As2O3. Model glasses confirmed our presumption of gradual development in the Bohemian glass batch recipes, which used very simple raw materials ratios.

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.

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