Ceramic Casting Molds from the Kruglaya Dolina Site in the Primorye Region: A Case of an Interdisciplinary Study

The article presents an interdisciplinary study of casting molds as one of the kinds of old technical (“metalworking”) ceramics. The material of the study is ceramic molds (47 whole and fragmented samples) unearthed at the Kruglaya Dolina settlement in the central Primorye region. The molds and other objects of technical ceramics (crucibles, nozzle) were found in destroyed, non-stratified cultural deposits and connected with the remains of bronze-casting workshops complex which was dated supposedly to the Bohai state period, 698-926. The study aimed (1) to examine the morphological and technological characteristics of the molds, and (2) to detect traces of alloys at the working surfaces of the molds. The study employed methods of binocular microscopy and laboratory refiring testing for (1), and scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), portable X-Ray fluorescence spectroscopy (pXRF) for (2). The analyzed ceramic molds were intended for the casting of semi-spherical buttons, several kinds of pendants, rosette-shaped openwork ornaments. Original bronze items which could be cast in these molds were not found at Kruglaya Dolina. According to the data on the morphological variability of the molds together with the results of the examination of the ceramic pastes technology, one can suppose that the casting molds were produced by different craftsmen or different workshops. SEM-EDS and pXRF analyses detected the traces of bronze alloys at 15 mold samples with carbonized working surfaces. Chemical elements - metals - lead (Pb), tin (Sn), and copper (Cu) are traced in various combinations at various samples. In some cases together with metals arsenic (As) is detected. The interpretation of these results follows methodological recommendations based on the published data of experimental research. The presence of certain elements can be stated, and their relative concentrations in the spectrum composition can be evaluated. However, it is necessary to take into account that the amounts of certain elements in the spectrum do not correspond to their amounts in the original alloy composition. Therefore, qualitative characteristics of the alloys can be determined, but not quantitative ones. According to the results, the three-component alloys containing copper, tin, and lead are recognized certainly. The tin-copper non-lead alloy and the “pure copper” alloy are supposed in some cases. Previous investigations on the old bronzes chemical compositions in southern Russian Far East revealed that three-component alloys (lead-tin-copper) containing arsenic had been used widely during the Bohai state period. Tin-copper and “pure copper” alloys were known at that time as well. It seems to be likely that the casting molds from the Kruglaya Dolina site are dated to the Bohai state period. Further researches of this site's bronze-casting workshops complex remains will focus on other categories of technical ceramics.

Keywords

Authors

References