A new fifteenth-to-sixteenth-century pottery kiln on the Tagus basin, Portugal

Abstract

A detailed archaeometric study of pottery was made of a fifteenth-to-sixteenth-century kiln located inside the walls of the Castle of Alenquer. The locally collected sherds are lead glazed, and mostly exhibit a green or dark yellow decoration. Only in one case, a fragment of a bowl, tin oxide was detected in the white glaze. Pastes from the ceramics of the Alenquer kiln were spectroscopically characterized in terms of their mineralogical and elemental composition. This pottery was fired twice, the first time at high temperatures to produce the biscotto, and the second time at lower temperatures to glaze the ceramics. Although only one type of raw material collected locally was used, two types of ceramic pastes were detected and organized into two groups: one produced at about 850 °C and another at about 950 °C. Pastes from Group 1 were converted into Group 2 pastes whenever the temperature of the kiln was raised from 850 to 950 °C, as confirmed by firing Group 1 pastes in an oven. These results were compared with those obtained for coeval ceramics, namely at Santo Antonio da Charneca and Mata da Machada. Both kilns were located on the south shore of the river Tagus (Lisbon), as previously reported. The first archaeometric study of ceramics produced in the kiln of Alenquer, (Portugal, fifteenth to sixteenth centuries) is reported, with the use of surface spectroscopies techniques, namely micro-Raman. Significant differences were found from two coeval kilns also located at the Tagus basin, Santo Antonio da Charneca and Mata da Machada.