Multi-technique characterisation of medieval mastic encrustation sculptures

Here we present the results of the examination of the mastic encrustations present on the medieval marble panels and precious cathedra in the San Nicola church of Bari (Italy). The matrix was analysed with Fourier transform infrared spectroscopy and pyrolysis gas chromatography-mass spectrometry. Organic binders were found and, in particular, the occurrence of heated Pinaceae resin, as well as of beeswax was assessed. The inclusions, including different types of rock, carbon black and opaque glass fragments, were characterised with optical microscopy, scanning electron microscopy, and powder X-ray diffraction. Micro-Raman spectroscopy was carried out on both inclusions and matrix.