M. Járó - L. Költő szerk.: Archaeometrical research in Hungary (Budapest, 1988)
Selected Bibliography - Summaries
Firing is a crucial factor in the pre-depositional history of pottery. During firing the phase and elemental composition change considerably as a consequence of exothermic and endothermic reactions. Solid state reactions rearrange the crystal structure, ferrous oxide transforms into ferric oxide, and water vapour, carbon dioxide t sulphur dioxide and volatile elements evaporate, as functions of firing temperature and atmoshphere. Some of the trace elements (cadmium arrd copper) can be mobilized easily at high temperature because of vitnfication of the ceramic material. Direct current arc excitation of clay samples heated at different temperatures (3501000°C) pfoved that the usually non-volatile trace elements (chromium, manganese, titanium, vanadium) evaporated to a greater extent, modifying the analytical results, if the ceramic matrix is in vitrified form. Samples to be analysed must be treated by heating at 800°C for 2 hours to get a quasi-uniform condition diminishing the effect of the firing process. Kardos J. — Kriston L.: A Sopron-Krautacker lelőhelyen feltárt kelta fazekas kemence anyagának vizsgálata röntgen diffrakció s elemzéssel (investigation of the material of a Celtic pottery kiln from Sopron-Krautacker dülő by X-ray) = Iparrégészet H, Veszprém 1984, pp. 107-110.(In Hungarian) Using X-ray diffraction analysis, crystalline phases were determined from samples taken from nine locations of the pottery kiln. It was found that the walls of the kiln were built from carbonate-free brown forest soil, while the grate and the flue tunnel are composed of the carbonate-rich level of the same type of soil in situ. Soil samples taken from the vicinity of the kilns were heated to different temperatures and the crystalline phases after cooling were analysed by X-ray diffraction. Through information on the crystalline phase of the pottery material, the firing temperature could be found. Analysis of pottery found in the kun indicates that the firing was a reduction type and the potsherds were heated to about 600-700°C. Kardos J. — Zimmer K. — Kriston L. — Morozova O. — Träger T. — Jerem E. : Scientific investigations of Sopron-Krautacker Iron Age workshop = Archaeometry 27/1. 1985, pp. 83-93. The operation of a pottery workshop can be characterized only incompletely by archaeological data, however a knowledge of the raw material and of the manufacmring processes are integral parts of -the overall picture. By using appropriate methods (X-ray diffraction, X-ray fluorescence spectroscopy and thermal analysis) and by taking advantage of the special features of the Sopron-Krautacker archaeological site (pottery kilns together with waste dumps and clay pits) some generalizations can be made. Clay with no or low cácium carbonate contents respectively, were used as a source of raw material by the Celtic potters although the utilization of clay with high carbonate content was also made possible by characteristics of the sou. The nearly carbonate-free upper layer of the local sou was formed by a leaching process. The vessels were fired at 600—700°C. This temperature was confirmed by investigation of the kilns. The Celtic potters must have chosen the non-calcareous layer intentionally, because calcium oxide as a decomposition product can destroy vessels. Calcium oxide can combine with water vapour in the air to form calcium hydroxide. Since the volume of calcium hydroxide is greater than calcium oxide or calcium carbonate, this expansion can exert enough pressure to rupture the walls. The recarbonization process
