Multi-technique investigation of archaeological pottery from Parma (Italy)

A ceramic factory with at least three kilns, active from the 14th century until the 17th century, was recently found close to the city walls of Parma (Italy). A series of measurements by different techniques was performed on pottery fragments belonging to the first and last production period. Micro-Raman spectroscopy and scanning electron microscopy–energy dispersive spectroscopy were used to study the glazes and the painting materials, while time-of-flight neutron diffraction and X-ray diffraction were used to characterize the ceramic bodies. The bodies are mainly composed by quartz, diopside, Na- and K-rich alkali feldspars, gehlenite, calcite, and silica-alumina glass; the red coloration is due to hematite. The glazes were obtained using a lead-silica glass, with a fictive temperature of about 600 ◦C. The main pigments were identified. The ceramics were produced from illitic calcareous clays and annealed in an oxidizing atmosphere at an estimated temperature of 900–1000 ◦C. Different amounts of magnesium in ceramics of the 14th and 17th century suggest the use of different quarries. The white pigment in the 17th century ceramics, showing the Raman spectrum of nearly pure anatase, is due to a titanium-bearing clay.