988 ISSN 1063-7745, Crystallography Reports, 2024, Vol. 69, No. 6, pp. 988–997. © Pleiades Publishing, Inc., 2024. On the Technology of Production of Antique Red-Glazed Pottery (Bosporan, Pontic, and Eastern Sigillata) A. V. Mandrykina a , D. V. Zhuravlev a,b , P. V. Guryeva a , E. S. Kovalenko a , O. A. Kondratyev a , D. N. Khmelenin a , E. Yu. Tereschenko a, *, and E. B. Yatsishina a a National Research Centre “Kurchatov Institute,” Moscow, 123182 Russia b State Historical Museum, Moscow, Russia *e-mail: elenatereschenko@yandex.ru Received September 17, 2024; revised October 1, 2024; accepted October 7, 2024 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 suspen- sion 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). DOI: 10.1134/S1063774524602466 INTRODUCTION Red-glazed ceramics (or terra sigillata) is high- quality Roman pottery, which appeared in the Eastern Mediterranean approximately in the middle of the 2nd century BC. Having arrived at Italy in late Repub- lican times, this pottery becomes popular and wide- spread throughout all Mediterranean, turning to the dominant type of tableware for several centuries. Its manufacture process was worked out to perfection, and the production was mass and strictly standardized. Nevertheless, the data from written sources con- taining information about the manufacturing technol- ogies of red-glazed ceramics are extremely scarce. King [1] draws attention to the term samiandum, which appears in the painting of the archaeological site from La Graufesenque when describing the slaves involved in the ceramic production. Having analyzed the evidence of ancient authors, King reliably deci- phers samiandum as the technological process of pre- paring of liquid coating or “slip” before depositing it on a vessel. However, a more detailed description of the recipe and production stages of red-glazed ceram- ics has not been found. The high degree of preservation of ceramic material under different natural conditions makes red-glazed ceramics an important chronological and economic marker. In this context, thorough studies of the spe- cific features of manufacturing technologies of red- glazed ceramics, providing additional information about production features, composition, and structure of the material of objects, as well as similarities and differences of technological processes in different regions, are highly important. Previously, studies of the sigillata manufacturing technology were carried out by modeling the tempera- ture and type of firing; the questions concerning the use of different types of clays to obtain necessary char- acteristics of the varnish layer were also investigated [2–9]. However, none of the researchers could reliably and completely reproduce the slip layer parameters (features of the varnish composition relative to the ceramic base, thickness, morphology, etc.), i.e., obtain the same parameters as in ancient samples. In view of this, the reconstruction of the manufacturing technology of red-glazed ceramics remains an urgent problem. In this paper, we report the results of studying the objects of Late Hellenistic and early Roman times, originating from the territory of the Bosporan King- dom, specifically, objects of red-glazed ceramics of three groups: Pontic, Bosporan, and Eastern sigillata, produced in different centers. CRYSTALLOGRAPHIC METHODS IN HUMANITARIAN SCIENCES