Micro-XRF analysis of a Brazilian polychrome sculpture

Abstract

Abstract In this work, microsamples extracted from a Saint John the Evangelist polychrome sculpture, dating from the beginning of the eighteenth century and found in Rio de Janeiro, Brazil, were analyzed with micro-XRF and complimentary X-ray Fluorescence (XRF) techniques, Raman Spectroscopy, and Optic Microscopy (OM). As a result of the study, the pigments azurite [2CuCO3·Cu(OH)2], massicot [PbO], vermilion [HgS], calcite [CaCO3] and gypsum [CaSO4.2H2O] were characterized. Through the images obtained by the microelemental mapping, it was verified that some tonalities were produced by pigment mixing, i.e., the green polychrome on the sculpture resulted from a mix of azurite and massicot. In addition to the characterization of the materials used in the sculpture, numerical iterations were implemented using Python programming language to perform correlations between the elemental maps, the values of which were validated by the results of the study.