COMPOSITION AND DISTRIBUTION OF CRUSTS IN WEATHERED STAINED GLASS WINDOWS THROUGH MAPPING AND CONFOCAL MICRO-RAMAN SPECTROSCOPY

摘要

Micro-Raman spectroscopy is a non-destructive and non-contact technique successfully used as analytical method for the study of historical objects and pieces of art. Therefore, it is becoming an appreciated tool for following the processes taking place at the surface of weathering substrates, as well as for aiding to accurate restoration and to study the effects of their conservation techniques. In the present work, confocal Micro-Raman and mapping techniques have been used for characterizing small unprepared pieces of glass from stained glass windows (XV-XVI centuries) of a renowned monument belonging to the Spanish Cultural Heritage: Avila Cathedral. The Raman results have assisted the conservators in the cleaning and restoring of the corresponding windows. Using a Renishaw Raman Microscope RM2000 and a portable EDXRF spectrometer, we have identified the corrosion, grisaille and glass compounds of the stained glasses and followed their distribution and intensity (mapping) at the surface. Confocal configuration, with the corresponding increase in the spatial resolution of the Raman measurements, has allowed to determine the thickness of the different layers.