The corrosion mechanism of lead-glazed pottery in Han dynasty

Ancient pottery, having endured prolonged burial in soil, invariably underwent the process of glaze corrosion. The micromorphology and structural composition of four lead-glazed pottery fragments dating back to the Han Dynasty, excavated in the Qinhan New Town within Xixian New area of Xi’an are elucidated by comprehensive analysis method. The results reveal that the corrosion products predominantly comprised PbCO3, Pb3(PO4)2, CaCO3, and Ca3(PO4)2. Concurrently, the presence of organic substances exhibiting characteristic self-excitation fluorescence in the cracks of the sample is identified through fluorescence microscopy and Fourier infrared spectroscopy. Through a comparative analysis of well-preserved and severely corroded samples, taking into account compositional analysis, observations of corrosion morphology, and the characteristics of corrosion products, it is deduced that the primary corrosion mechanisms involve chemical corrosion, microbial corrosion, and crack corrosion. This study provides a comprehensive depiction of glaze corrosion process inherent to lead-glazed pottery and establishes corresponding corrosion models.