Metalworking in Bronze Age China: The Lost-Wax Process By Peng Pe ...

also the most frequently seen Erlitou vessel type.⁶² The fact that the jue cup was cast in a single pour further increases the difficulty posed in the construction of its mold assembly.⁶³ Aside from many examples of minor repairs on bronzes, no evidence of joins is known in the fabrication of Erlitou bronzes;⁶⁴ all known Erlitou bronze vessels seem to have been cast in a single piece by the section-mold process. The earliest bronze decoration known in China, a raised pattern of simple lines and bosses on a jue cup from Erlitou (fig. 8), was apparently formed by carving into the interior of one mold section.⁶⁵ This mold-carving decorative strategy indicates that the Chinese bronze ornament originated as fundamentally subdivided, with compartmentalized patterns conforming to the divisions of the mold.⁶⁶ Even after craftsmen later began to chiefly decorate the model, this characteristic continued as an integral aspect of Chinese bronzes throughout the early Bronze Age.

The Erligang bronze industry (c.1500–1300 BCE?),⁶⁷ succeeding the Erlitou tradition, had its own technological breakthroughs, primarily in two respects. The first breakthrough came with interlock casting,⁶⁸ a stepped-fabrication process that allowed for the joining together of bronze pieces during successive pours of metal.⁶⁹ Significantly, it could sidestep the withdrawal of mold sections from an intricately shaped model and avoid trapping pockets of air, a problem from which even the lost-wax process is not free.⁷⁰ This method may have originally been devised to make repairs,⁷¹ as casting-on, a variation of this technique, was already being practiced during the Erlitou period to patch flaws.⁷² Interestingly, Erligang founders still had a strong preference for casting vessels in a single pour,⁷³ as evidenced by many vessels produced by that method (e.g., the round ding in fig. 9, with its casting process shown in fig. 7).

Another contribution of Erligang metalworkers was the use of metal spacers, which were scrap-like pieces of bronze fixed between core(s) and their mold, with the purpose of maintaining a consistent gap between mold and core that would result in vessel walls of uniform thickness.⁷⁴ Spacers, presumably recycled from casting fragments, would not have