How were Chinese bronze vessels made during the Shang period?

During the Shang period (c. 1600–1046 BCE), Chinese bronze vessels were created using a sophisticated technique known as piece-mold or sectional-mold casting. Contrary to earlier theories, this process did not utilize the lost-wax method.12

The production process involved several precise steps:

• Model and Core Creation: Artisans first crafted a clay model of the desired vessel. For vessels, this model was trimmed to serve as a core, representing the interior cavity.12
• Mold Preparation: The model was encased in clay, which was then sliced into three or four sections to create the mold. These sections were removed, and the original model was eliminated.12
• Assembly: The mold sections were reassembled around the core, using metal spacers to maintain the necessary gap between the mold and the core.12
• Casting: Molten bronze—an alloy of copper, tin, and sometimes lead—was poured into the hollow space.1
• Finishing: Once the metal cooled, the mold was broken away. Final steps included polishing away flaws and excess bronze. Appendages like legs or handles were often cast separately and integrated using a "lock-on pour".12

Decorative patterns were either incised into the mold to create raised designs on the finished vessel or applied to the model surface.12