Bronze alloying recipes at Anyang during the Shang Dynasty

Abstract

We present a detailed analysis of the chemical alloying data (Cu, Sn, Pb) on the bronzes recovered from the Late Shang capital at Yinxu, revealing a complex pattern which varies by social status and object typology, and which also changes over time. The preference for higher tin in the bronze vessels and weapons for the elites during Yinxu Phase II gives way to a more binary pattern (with weapons being preferentially alloyed with lead) for the lower elites of phase II, which becomes prevalent in subsequent phases. These changes are interpreted in terms of different ‘alloying practices’, which attempts to reconstruct the way in which the alloys are created at the point of casting. The alloy type described here as A1/A2 (11–24% tin, 0 to 3–5% lead) seems most likely to have been created by mixing together three components, corresponding to mixing relatively pure copper, tin and lead. This contrasts with the suggestion in the Kaogong Ji, several hundred years later, that binary pre-prepared alloys were used. It is now important to determine when such a change might have occurred. The suggestion that alloy type B (low tin, variably high lead) could have been made by combining pure copper with a slightly impure lead (95%Pb/5%Sn) hints that such practices might have started during the Shang, but requires more work, especially on the intervening Western and Eastern Zhou periods.