Original title: Surface chromium on Terracotta Army bronze weapons is neither an ancient anti-rust treatment nor the reason for their good preservation
Researchers tested bronze weapons, lacquer, and soil from the Terracotta Army site. They found that chromium on the weapons tracked the kinds of objects nearby, not how well the bronze had survived. Tests showed that lacquer contains chromium, which spread onto the metal after burial. The weapons' good condition probably came from their bronze and from soil that was mildly alkalineA chemical condition on the opposite side of the scale from acidic. and made of very small particles.
Imagine storing metal tools beside a painted wooden box. If traces of paint later appear on the tools, that does not mean the tools were painted to protect them. In this paper, the lacquer is the box: chromium from it moved onto nearby bronze after burial, while the soil and bronze likely explain why the weapons stayed in good condition.
The finding changes how archaeologists explain why these bronze weapons survived so well. It points instead to the burial soil and the bronze itself, helping researchers distinguish ancient technology from materials that moved after burial.
The abstract says the weapons' good preservation probably results from soil conditions and bronze composition, but it does not establish the precise contribution of each factor. It also does not describe the number or range of objects tested, or how well the results apply beyond the studied site.
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Surface chromium on Terracotta Army bronze weapons is neither an ancient anti-rust treatment nor the reason for their good preservation — Marcos Martinón‐Torres, Xiuzhen Janice Li, Yin Xia et al. — Scientific Reports — doi:10.1038/s41598-019-40613-7
Abstract licence: CC BY
Explanation generated by Synthesis from the abstract — it is not the original paper.