Analisi archeometriche e statistiche per la caratterizzazione di produzioni di bucchero

The aim of this paper is to provide an update to the debate concerning the production technology of bucchero pottery, as well as presenting new data on the use of raw material for its manufacture and the temperatures of firing. This interdisciplinary research focused on a period of technological changes in bucchero production during the sixth century BC, by applying a quantitative analytical approach using X-Ray powder Diffraction (XRD), X-Ray Fluorescence (XRF), Thermogravimetric Analysis and Differential Thermal Analysis (TG-DTG), and multivariate statistical analyses. A series of samples from northern Etruria (mainly the area of Volsinii) were compared with products from Veii, Ardea, Segni and Pompeii. XRF and XRD analyses provided quantitative results, statistically analysed, concerning the use of raw material, both calcareous and non-calcareous, and the technology of firing where temperatures reached 950°C or above. TG analysis proved that the black surface of bucchero was due to reduced iron oxides and the presence of carbonaceous material on the surface. However, XRD results demonstrated that firing occurred at a high temperature and the ratio between aluminium and iron in the samples led to the formation of hercynite, an iron-aluminate spinel. The results of the study show that during the sixth century BC the changes in technology to obtain a quality bucchero production were related to a sufficiently long soaking period at a high temperature in a reduced atmosphere, regardless of the presence of calcite in the source material