The role of Raman microspectroscopy in the study of black gloss coatings on Roman pottery

Raman microspectroscopy was adopted for the study of black gloss coatings on Roman pottery, found in Rimini (northern Italy) and in Suasa, near Ancona (central Italy), dated second century B.C. This non‐destructive technique allowed a very accurate analysis of the crystalline and amorphous components of thin surface layers. The investigated coating is black, homogeneous and glazed, without any crystals, becoming red on approaching to the ceramic body. Magnetite and carbon are the main phases of the black zones, whereas hercynite, quartz, silicates and haematite are the secondary components. In the red zones, approaching the ceramic body, the amount of haematite increases and the amount of magnetite decreases. The presence of carbon, on the surface only, confirms the hypothesis of a firing cycle in a partial reducing atmosphere.