Archaeometric investigations of medieval stained glass panels from Grodziec in Poland

Abstract

Two stained glass panels of Austrian origin from the 15th century were formerly placed in Grodziec castle in Poland and nowadays they belong to the collection of the National Museum in Wrocław. The main aim of this work was to evaluate the chemical composition of glass from medieval and modern parts of the panels. Elemental composition of bulk glass and external layers of glass samples was determined with the use of SEM-EDX and LA-ICP-MS methods. Morphology of the deteriorated glass was investigated through SEM-BSE images of the cross-sections. Moreover, the longitudinal concentration profiles were determined by LA-ICP-MS measurements. Results show that stained glass panels reveal characteristic elemental composition of wood ash glass produced from 1000 to 1400 AD. Almost equal proportions of potassium and calcium oxides indicate that high quality of beech wood was applied by manufacturers. Main and minor elements content was common for almost all investigated glass samples, which suggests that manufacturers follow strictly the assumed recipe during panels production. Differences in elemental composition detected for minor or trace elements were connected to colour additives. Stained glass samples from glazing exhibit composition of typical modern glass. Considerable differences between the composition of healthy bulk glass and the deteriorated surface of glass were detected though SEM-BSE images and LA-ICP-MS longitudinal concentration profiles. High concentrations of lead, copper and iron were noticed in external layers of glass samples, which can be explained by the presence of decorative paint layers and drawings.

Dating Nathan: The Oldest Stained Glass Window in England?

“…Most colors are found in b ures, excluding light blue (Methuselah's shoes) and pink (Ezekias' footstool). The trace element concentrations of the glass as analyzed by handheld pXRF are in general terms consistent with previously published trace element data for medieval stained glass (e.g., [7,25,37,73,74]). However, the glasses used to glaze the two figures have distinct chemical characteristics (Figure 6).…”