Characterization of black filling in cast designs of Shang dynasty Chinese bronzes

This paper reports on the formation of intentional black fillings in design areas of ancient Chinese bronzes. The black filling in the design channels contrasts with the golden color of the freshly cast bronze. Silicate grains in the cast design channels that appear similar to processed loess used for casting molds formed a base for applying black filling materials . Using Py-GCMS, the major organic component found was composed of fatty acids including azelaic acid , suggesting that a drying oil was used. In addition, evidence of soot and possibly Anacardiaceae lacquer were found.