The use of a portable energy dispersive x-ray fluorescence spectrometer for the characterization of patinas from the architectural heritage of the Iberian peninsula

This article focuses on the study of patinas by means of a non-destructive and fast energy dispersive x-ray fluorescence (EDXRF) technique using portable equipment. The term patina is referred here to thin films or coverings (5-500 μm thick) on the surface of stone building materials, characterized by a common yellowish colour and a common presence of calcium carbonate, calcium sulphate, calcium oxalate, calcium phosphate, silicate and iron oxide and/or hydroxide. Some of these patinas are the result of applied past treatments with protective and/or aesthetical purposes. The main aim of this article is to assess the potential of the technique, together with the determination of the elemental composition of the samples and the provision of analytical information leading to the discrimination between different types of patinas. This work proved that the EDXRF spectrometry is a useful technique for qualitative and even semi-quantitative analyses of patinas in situ. It is a reliable method for a first approach to the study of a patina of any building. The results obtained showed that the patina is characterized by the presence and enrichment of elements like Si, P, K, Fe, Ti and Mn. For this reason, they could be considered as characteristics of this kind of material.