Термомагнитно изследване на средновековна битова керамика от Велики Преслав. Част I
Тhermomagnetic analysis of mediaeval household pottery from Veliki Preslav. Part I
The article presents the results of the thermomagnetic analysis of pottery from the excavations of the Royal Church in the Palace Center of Veliki Preslav. The selected samples were found in stratigraphic layers that cover a broad chronological range – first half of the 10th until the middle of the 13th century. Amongst them are fragments of cooking vessels, tableware and amphorae, made with a hand-driven or pedal-driven potter`s wheel. According to their different technology of manufacture and decoration, they are divided into 13 groups (Table 1).
The analysis of the results for each of the tested groups leads to the following conclusions. During the 10th century, the pottery production in Veliki Preslav had a wide assortment that adhered to high technological standards. The firing temperatures of kitchenware are between 730 – 930 °C with an average of 818 ± 72 °C, while these of the glazed tableware are tendentiously higher varying from 890 to 950 °C with an average of 922 ± 28 °C (fig. 17). These high requirements to the quality of the ceramics production were directly related to the promotion of the town as a leading economic center of the country and the consequent rapid development of trade and crafts there.
In the course of the 10th and 11th centuries, pottery made on a hand-driven potter`s wheel was baked at temperatures between 730 °C and 950 °C. At higher temperatures ranging from 790 °C up to over 1000 °C, were fired vessels made on a pedal-driven potter`s wheel (fig. 16).
A radical change in the pottery production of Veliki Preslav occurred at the beginning of the 13th century. The temperatures of 750 – 790 °C were sufficient for firing of kitchenware in the 12th and 13th centuries (fig. 18). Tableware had an extremely rich repertoire, but its technical implementation was not always at a high level. Higher temperatures were obtainable in the kilns at firing table unglazed and glazed vessels – respectively 790 – 910 °C and 830 – 970 °C (fig. 18). Pottery with slip decoration was fired at an average temperature of 897 °C. The production of sgraffito ceramics, which started at the beginning of the 13th century, still lacked sustainable standards and vessels had been fired at various temperatures from 830 to 970 °C. Similar firing temperatures were identified for the amphorae from the considered periods (10th – 11th and 12th – 13th c.) – between 790 °C and 850 °C (fig. 17, 18).
Some further observations can be made about the ceramic production of Pliska and Veliki Preslav at comparing the results from the thermomagnetic analysis of samples representing both metropolitan centers (fig. 19 – 22). There are no significant temperature differences in the kitchenware and amphorae (fig. 19, 22). However, a clear trend exists for the tableware – glazed and non-glazed. Definitely higher firing temperatures correspond to the Veliki Preslav vessels (fig. 20, 21). This is probably due to the rise of the city as a leading production center, which is catalyzed by the intense economic relations with Byzantium and access to the technical innovations of the epoch.