X-ray computed tomography reveals special casting techniques used with unusual bronze objects unearthed from the Sanxingdui site

Scholars in a wide range of disciplines are interested in the casting techniques used to create the extraordinary bronze objects unearthed from the two pits of the Sanxingdui site. Although researchers have carried out a number of studies on this topic, many technical details remain unclear. This paper offers the first examination of bronze objects from the Sanxingdui site using industrial computed tomography (CT) and provides direct evidence for interpretation of the complicated casting process involved. We show that multiple pouring and various joining techniques were widely used during the casting of bronze objects from the Sanxingdui pits. The precast parts were mechanically connected with one another by the later pouring, which was the crucial technique for the casting of complicated objects. Representative features include the cast-on cramp device of the sun-shaped objects and the tenon connection with dowel found inside many branches of the bronze trees. This paper also describes evidence of core rods made of different materials, which is the earliest example of this technique in ancient China.