New data on the weaponry of the terracotta army (technological aspect)

This article presents the results of studying protection methods against corrosion in bronze weapons which were found in the Mausoleum of Qin Shihuangdi. Even during the first season of excavations, well-preserved weapons with traces of chromium on the surface were discovered. Based on these findings, it was suggested that the Qin artisans knew the chromium plating process, when protective film was applied by immersing a bronze item in a container with solution of chromic acid salts. However, this technology is very complicated; it was fully mastered only in the early 20th century. Moreover, less than a dozen weapons were presented as examples of such a technology already in the Qin period (late 2nd century BC), which is not enough for such large-scale conclusions. Therefore, nowadays, an international team of scholars led by M. Martinon-Torres attempted to find a solution to this problem. As a result of their multidisciplinary studies, it has been established that traces of chromium on the surface of weapons are not directly associated with its good preservation. Particles of this metal were contained in lacquered fittings (scabbard, overlays on the handle, etc.), from where they penetrated into the composition of bronze. In the composition of lacquer, chromium ions appeared from treatment with chrome alum, well known to the Qin leatherworkers who could also use it for accelerating polymerization of lacquer tree sap. As far as really good preservation of bronze weapons found in the excavations is concerned, it was explained primarily by specific features of soil in the Mausoleum area (low acidity, fine dispersion, small amount of organic matter, etc.).