Analyses of the stained glasses of Certosa di Pavia

In the planned restoration of the stained glass windows of the 'Certosa di Pavia' presently in progress, systematic elemental energy-dispersive x-ray fluorescence (XRF) analysis of glasses has been undertaken on the request of 'Soprintendenza per i Beni Ambientali e Architettonici'. Analyses of fragments from the first two window-panes ('S. Girolamo' and 'Presepe') have been performed. For homogeneous glass samples, quantitative analyses have been obtained by using a secondary XRF set-up and applying the method of measuring Compton scattering intensity to evaluate self-absorption corrections. This procedure proved to be effective, as it was checked after comparisons with several standard glass analyses. Also, lateral cross-sections of each sample have been examined by a 100 μm capillary x-ray microprobe, so that elements characteristic of glass composition can be discriminated from those due to surface contamination (from lead bindings, for instance). X-ray microprobe was also a method suited for analyses of layered glasses, as well as spotted small areas or grisaille zones.