Micro-Raman measurements were performed on two Etruscan polychromes on architectural terracotta panels now on display at the Villa Giulia Etruscan Museum in Rome. These painted panels, dated from 530 to 520 B.C., are of particular interest because of the unusual presence of green and blue layers. Etruscans in the Archaic Age indeed mainly used white, red, and black colours for painted terracotta panels. Raman spectra allowed the analytical identification of green (malachite) and blue (Egyptian blue) pigments employed by Etruscans for this kind of artistic production. This finding provides evidence for a larger use of malachite and Egyptian blue, previously well documented only in Etruscan wall paintings. The use of different pigments to obtain different colour tones has been also observed. Egyptian blue is indeed mixed with malachite to obtain different green tones, and a black pigment seems to have been applied over the Egyptian blue layer to obtain a dark blue tone.

Painted terracotta slabs, which are characteristic of Etruscan art, are much less known than the funerary frescoes of the Etruscan necropolis, and have never been studied by advanced diagnostic techniques. To get information on the manufacturing methodology of these important works of art, detailed micro-Raman and X-ray diffraction measurements were performed on a polychrome terracotta slab representing a warrior, found in the ancient Etruscan town of Ceri. We have found that the terracotta slab, which was made using a calcium-poor clay, was fired at a temperature in excess of 800 ° C. For the polychrome, we have identified red ochre, azurite, yellow ochre, burnt umber and carbon black pigments, and we propose the use of kaolin as a white pigment, thus providing a reliable, although not definitive, description of the colour palette. On the basis of the obtained results, which do not reveal the presence of organic binders, we propose that a second firing procedure was carried out on the work of art at between 250 ° C and 300 ° C, in order to fix the pigmented layers.

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