Kun Zhao’s scientific contributions

For forty years, there has been a widely held belief that over 2,000 years ago the Chinese Qin developed an advanced chromate conversion coating technology (CCC) to prevent metal corrosion. This belief was based on the detection of chromium traces on the surface of bronze weapons buried with the Chinese Terracotta Army, and the same weapons’ very good preservation. We analysed weapons, lacquer and soils from the site, and conducted experimental replications of CCC and accelerated ageing. Our results show that surface chromium presence is correlated with artefact typology and uncorrelated with bronze preservation. Furthermore we show that the lacquer used to cover warriors and certain parts of weapons is rich in chromium, and we demonstrate that chromium on the metals is contamination from nearby lacquer after burial. The chromium anti-rust treatment theory should therefore be abandoned. The good metal preservation probably results from the moderately alkaline pH and very small particle size of the burial soil, in addition to bronze composition.

This paper explores the integration of chemical data with metric studies and spatial analyses of archaeological artifacts to investigate questions of specialization, standardization, and production organization behind large-scale technological enterprises. The main analytical focus is placed on the 40,000 bronze arrowheads recovered with the Terracotta Army in the First Emperor’s Mausoleum, Xi’an, China. Based on the identification by portable X-ray fluorescence spectrometry of chemical clusters that correspond to individual metal batches, and combined with a study of their context in the tomb complex, we argue that the manufacture of arrows was organized via a cellular production model with various multi-skilled units rather than as a single production line. This system favored more adaptable and efficient logistical organization that facilitated dynamic cross-craft interaction while maintaining remarkable degrees of standardization. We discuss the use of “the batch” as an analytical category and how our method might be applied to other studies of craft organization in complex societies and imperial systems.

Structure-from-motion and multiview-stereo together offer a computer vision technique for reconstructing detailed 3D models from overlapping images of anything from large landscapes to microscopic features. Because such models can be generated from ordinary photographs taken with standard cameras in ordinary lighting conditions, these techniques are revolutionising digital recording and analysis in archaeology and related subjects such as palaeontology, museum studies and art history. However, most published treatments so far have focused merely on this technique's ability to produce low-cost, high quality representations, with one or two also suggesting new opportunities for citizen science. However, perhaps the major artefact scale advantage comes from significantly enhanced possibilities for 3D morphometric analysis and comparative taxonomy. We wish to stimulate further discussion of this new research domain by considering a case study using a famous and contentious set of archaeological objects: the terracotta warriors of China's first emperor.

The Terracotta Army that protected the tomb of the Chinese emperor Qin Shihuang offers an evocative image of the power and organisation of the Qin armies who unified China through conquest in the third century BC. It also provides evidence for the craft production and administrative control that underpinned the Qin state. Bronze trigger mechanisms are all that remain of crossbows that once equipped certain kinds of warrior in the Terracotta Army. A metrical and spatial analysis of these triggers reveals that they were produced in batches and that these separate batches were thereafter possibly stored in an arsenal, but eventually were transported to the mausoleum to equip groups of terracotta crossbowmen in individual sectors of Pit 1. The trigger evidence for large-scale and highly organised production parallels that also documented for the manufacture of the bronze-tipped arrows and proposed for the terracotta figures themselves.

This paper is concerned with the inscriptions and finishing marks present on the surfaces of the thousands of bronze weapons recovered together with the Terracotta Army at the mausoleum complex of Qin Shihuang, the First Emperor of China (259–210BC). After utilising the textual information from the inscriptions to reconstruct aspects of labour organisation and political control during the production of the weapons, the work concentrates on documenting and explaining the techniques employed to produce the inscriptions, to file casting imperfections, and to obtain the smooth, shiny and sharp finish still noticeable on many of the weapons. Silicone rubber impressions of surface features of swords, lances, crossbow triggers and arrows were examined under the scanning electron microscope (SEM), and these observations were supplemented with examination of the artefacts under the stereomicroscope and the SEM. The evidence indicates the use of a variety of chisels for making the inscriptions, and of files for removing excess metal from surfaces. In addition, the grinding and polishing marks demonstrate the large-scale, systematic use of rotary wheels to achieve an ideal final polish. These findings are contextualised in the broader history of Chinese metallurgy, with special attention to the emergence of iron tools and of rotary mechanical devices.