Non-destructive characterisation of glasses and grisailles from Segovia Cathedral stained glass windows

摘要

The characterisation of stained glass windows belonging to the Segovia Cathedral was performed by non-destructive analyses. The work aimed at finding the composition of the glasses and decorations, and relating them with the corresponding production periods. The chemical composition of the glasses was obtained by portable X-Ray Fluorescence Analysis (XRF). The structural characterisation of the glasses, corrosion products and grisailles were also performed by optical microscopy and μ-Raman. Another important aim of this work was to get information about the composition of ancient and modern grisailles. This aspect is of fundamental importance for the experts that are working in the restoration, since it is necessary to make the reinstatement of many pieces of the windows that were broken or very degraded. Most of the grisailles currently available are not really suitable for glass painting. In this work, we analysed good quality grisailles that have been out of production since 1960, to get useful information to reproduce these materials. The presence and distribution of iron, lead and copper on 1960s grisailles were studied by voltammetric techniques and by Scanning Electron Microscopy (SEM).