Decorated pottery study: analysis of pigments by X-ray absorbance spectroscopy measurements

Characterization of pigments on decorated pottery fragments has been fully carried out by nondestructive x-ray absorbance spectroscopy (XAS). The samples were a series of pottery shards excavated from the archeological site of Caltagirone (Sicily, Italy), a well-known ceramic production center. Aesthetical criteria and morphological observations allowed us to attribute the samples to quite different historical periods, starting from the 18th century B.C. up to the 16th century A.D. An extensive time interval led us to suppose that different materials and techniques were used for the production of the ceramic paste and also for the preparation of pigments. XAS measurements were performed at the Cu and Fe K-edges. The analysis was carried out both in the near-edge (x-ray absorption near-edge spectroscopy, XANES) and in the extended (extended x-ray absorption fine structure, EXAFS) region. From the results, we observed Fe oxides as the main pigmenting agents in the most ancient fragment, while in the other ceramic shards, besides Fe oxides, copper oxides were also found. Oxidation states and local environments of the atoms present were characterized.