On the Technology of Production of Antique Red-Glazed Pottery (Bosporan, Pontic, and Eastern Sigillata)

Abstract

Based on comprehensive studies of fragments of antique red-glazed pottery (terra sigillata) of the Pontic, Bosporan, and Eastern groups, characteristic technological features of the slip layer and ceramic bulk have been identified. The Eastern-sigillata samples exhibited the best quality. The small size of the pores and inclusions suggests the use of finely dispersed clay. In addition, a mixture of two types of clay (ferrous and more refractory calcareous) was revealed. The special and, apparently, careful preparation of the clay suspension for the slip layer production included addition of a potassium-containing preparation, presumably, potassium potash (to glaze better the layer), as well as an iron-containing pigment, likely, ochre. The firing temperature for this group of samples was about 1000°C. Pontic sigillata products differed from the Eastern pottery by a lower content of potassium potash and the absence of specially added pigment in the varnish layer. The firing temperature was lower: 850–900°C. The Bosporan products are characterized by much less thorough preparation of both the clay raw material as a base and the varnish layer, as well as the lowest firing temperature in comparison with other groups (500–900°C).