On the soldering techniques of gold objects from the Boma site, Xinjiang, China

The soldering techniques used in ancient goldwork are of great interesting for scholars from various disciplines. In this paper, the soldering techniques of the 3rd to 5th century CE gold artefacts from the Boma site in Xinijang are investigated based on micro-analysis of cross-section samples. The results show that Au-Ag-Cu ternary alloy with high silver and copper content was used as solder material for connecting gold wire onto the arm armor, while copper salt bonding was used for the granulation of the finger ring and scabbard. The unusually slight compositional differences in the joining areas of the Boma granulation samples remind us of their complicated heat treatment, a crucial aspect for the understanding of ancient goldsmithing to which more attention needs to be paid.