Image shows “Mirror 1”, with feather and hook pattern, Warring States period (475-221BC)
The hidden pasts of four, antique Chinese bronze mirrors have been revealed using the gentle and non-invasive technology of photon counting computed tomography.
The project, to conduct a forensic study of these valuable yet often little understood items, was undertaken by academics and researchers from the Architectural Conservation Laboratory, the Department of Physics, the Faculty of Medicine and also the Planetary Spectroscopy and Mineralogy Laboratory at the University of Hong Kong.
Chinese bronze mirrors date as far back as the Neolithic period but their design and the techniques used to create them evolved and were refined over centuries, with the finest examples produced in three significant historic periods: the Warring States (475-221BC), the Han (202 BC – 220 AD), and the Tang (618 – 907 AD).
However, although these mirrors are important and sought after works of Chinese craftsmanship, even those in reputable collections remain something of a mystery. Typically, little is known of their provenance, with documents relating to ownership limited to decades rather than centuries.
The team at the University of Hong Kong describe how they undertook their study in order to show that it was possible to “provide valuable diagnostic information, based solely on the physical evidence inherent in potential artefacts… retrieved via a careful, multi-faceted, forensic science appraisal with no preconceptions as to the artefacts origins”. From a broader perspective, their work demonstrates how museums and universities can explore the authenticity of objects even when archaeological context is absent.
Researchers had a range of leading technologies to work with, using a MARS tomographic 3D X-ray spectral scanner to produce sagittal X-ray scans of the mirrors. This was the first time the photon counting based technology, with high spatial resolution and low noise, had been applied to such a task but the results, particularly in relation to “Mirror 3”, proved fascinating.
X-ray image of “Mirror 1” obtained using MARS photon counting X-ray detector