Black gloss pottery: production sites and technology in northern Etruria. Part II: gloss technology

The present study aims to understand the reasons for the visual differences of black gloss pottery found in northern Etruria. The results obtained by conventional (scanning electron microscope, electron microprobe) and synchrotron (X-ray diffraction, X-ray absorption spectroscopy) techniques indicate that the thickness, porosity or chemical composition of the different types of gloss cannot be used as the principal distinguishing factor. The size of quartz or feldspar crystals may well be a critical factor responsible for the matt effect in some samples, while the range of mixtures of iron compounds indicated by XRD and XAS could be the reason for differences in colour and reflectivity. The Fe L-edge XAS results in particular show that a correlation does exist between the oxidation state characteristics and the visual appearance. The Si, Fe and Al contents seem to further discriminate the different types of gloss that have differing visual appearances.