Degradation mechanism of the Ru wares unearthed from the Qingliangsi site in Henan,China

The Ru kiln is a famous kiln that originated in the Northern Song Dynasty (960–1127 CE) in China. After nearly a thousand years of degradation, many ‘white spots’ have appeared on the Ru glazes, which have seriously damaged the visual aesthetic. Energy-dispersive X-ray fluorescence spectroscopy (EDXRF), X-ray diffraction analysis (XRD), optical microscopy (OM), scanning electron microscopy-energy dispersive spectrometry (SEM–EDS), Raman spectroscopy, and angle-resolved spectrum system were used to systematically investigate the composition, microstructure, and degradation morphology of the Ru ware. The degradation mechanism of the Ru glaze was investigated, showing that the heterogeneity of the glaze microstructure resulted in different degradation morphologies. The weakest part determined the overall corrosion resistance. Fine crackles of the glaze provided a fast path for corrosion. The special soil environment at the Qingliangsi site was a key influencing factor leading to the ubiquitous and severe degradation of the Ru wares. The microstructure degradation caused by chemical corrosion provided complex light-reflecting interfaces, leading to the formation of ‘white spots’ on the surface. Combined with the influence of exotic contaminants, the color and texture of the Ru glaze significantly changed, and the appearance quality seriously declined.