Microanálisis de capas pictóricas en esculturas policromadas

abstract cross section samples from polychrome wood sculpture are analyzed by optical microscopy, the nuclear techniques: micro-x ray fluorescence, micro- proton induced x-ray emission coupled with rutherford backscattering and the traditional method by scanning electronic microscopy with energy dispersive x-ray fluorescence detection (sem-edx) micro-analytical methods. special emphasis is dedicated to μxrf, a novel advanced technique developed thanks to the last achievements of the x-ray optics that can be available by modifying conventional laboratory xrf spectrometer, representing an alternative to the traditional and expensive sem-edx stratigraphic analysis of pictorial works. the results are compared with respect to spatial resolution to differentiate pictorial layer structure and elemental sensitivity. number of layer, relative position of layer, layer thickness and chemical composition of pigments are determined in the characterization of valuable polychromies of once church san juan de letrán in order to obtain information about their "material history" that should contribute to its provenance and attribution research. the pigments used in this artistic works were identified by their characteristic elements. the elemental distribution maps obtained by the used nuclear techniques precisely reproduced microphotographies obtained by means of light microscopy.