Assessment of impressed/moulded ceramic wares excavated during the 2018-2019 seasons at the Iznik Tile Kilns Excavation and analysis results with a pXRF instrument on selected samples

Abstract

Iznik reached the peak of its ceramic and tile production between the 14th- and 17th- centuries. Recent findings at the Iznik Tile Kilns Excavation carried out in the BHD coded excavation area in Iznik District center revealed that ceramics had been produced there using an impressed/moulded technique , which was widely used in non-Anatolian Islamic ceramic art. These types of ceramics, which are thought to have been intensively produced after Iznik passed into Ottoman administration in 1331, were classified into two main groups in terms of their forms and decorations. Moreover, during the 2019 excavation season, characterization studies were carried out using a portable XRF (pXRF) instrument on seven selected samples in order to determine the body, slip and glaze composition. The results showed that the sample without a slip contained calcium-rich clay (high calcium and high alumina). The analyses of the molding materials confirmed earlier studies which had determined that the paste used (the third type of paste) had been calcareous or calcium-rich clay. Moreover, the sample with slip contains a greater amount of quartz (55.4 wt%) than the sample without slip (44.2 wt%). Of interest is that the sherd which is covered with a turquoise glaze contains 24.6 wt% lead-oxide (PbO) and 6 wt% tin oxide (SnO2). This glaze composition may indicate that the artifact was produced in the earlier period of Iznik production, namely at the end of the 15th century. Another glazed mold from among the samples analysed does not contain any tin oxide and has a higher amount of PbO which indicates a later production date (17th- century). The pXRF measurement results suggest that the mold may have been produced in an earlier period, and then glazed later for decorative and/or technical purposes.