Pigment identification on Campana reliefs from the Palatine Hill and Colosseum Valley in Rome

This article shows the first pigment identification of the Campana reliefs, Roman architectural earthenware plaques. The Campana reliefs polychromy were investigated by applying a multidisciplinary approach involving non-invasive and micro-destructive techniques to some fragments with traces of colour found on the north-eastern slopes of the Palatine Hill in Rome. X-ray fluorescence analysis and reflectance measurements provided preliminary identification of pigments, which was subsequently confirmed by X-ray diffraction and elemental mapping by scanning electron microscopy-energy dispersive spectrometry carried out on micro-samples and cross sections, respectively. Yellow ochre, red ochre, lead white, calcium-based white pigment, Egyptian blue and minium were identified. In addition, PIL (Photo Induced Luminescence) imaging was performed, identifying the macro-distribution of Egyptian blue, even on plaques without visible traces of colour.