Application of analytical techniques to the unveiling of the glazing technology of medieval pottery from the Belgrade Fortress

Medieval glazed ceramics, dated to the early 15th century, excavated at the Belgrade Fortress, Serbia, were investigated by combining optical microscopy, X-ray powder diffraction (XRPD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), micro-Raman spectroscopy and multivariate statistical analysis. The decoration and style of the investigated ceramics were characteristic of workshops from different areas of the medieval Serbian State: Ras, Krusevac and Belgrade/Smederevo. Comparison was made with ceramic samples from the same period excavated at the Studenica Monastery, the hitherto earliest workshop discovered, which were used as reference material for the Ras area. Ceramics from the Belgrade Fortress were covered with a transparent, lead-based glaze. The majority of the glazes were produced by application of mixture of lead oxide and quartz to the clay body, whereas only two samples were glazed by application of lead oxide by itself. The brown colours of the glaze originated from Fe-based spinel, whereas copper and iron were responsible for the colouring of the green and yellow glazes. The obtained results revealed glazing technology taken from Byzantine tradition.