Corrosion Mechanism of a Jingdezhen Bluish-White Porcelain from the Nanhai I Shipwreck: The Ash-Green Glaze of the Early Song Dynasty

This study investigates the long-term degradation processes and underlying mechanisms of a complexly corroded bluish-white porcelain sherd produced at the Hutian kiln in Jingdezhen, dating to the early Northern Song Dynasty, which was recovered from the Nanhai One shipwreck. A multi-analytical approach was employed to characterize the chemical composition, microstructure, and phase constitution of the sample. The results reveal the presence of SiO _x spheres within the glaze bubbles, some of which possess a well-aligned submicron particle structure. The dissolution-reprecipitation and secondary crystallization of these metastable amorphous phases, accelerating the corrosion process and leading to the dense distribution of white spots, arc-shaped cracks, and corrosion pits on the glaze surface. Moreover, the high porosity of the ceramic body and glaze could provide an ideal anoxic microenvironment for anaerobic microorganisms, facilitating the formation of FeS ₂ . To understand the intrinsic correlation between the corrosion behavior and the original microstructure of the glaze, this study also provides a fundamental analysis of the processing defects in this specific artifact, with reference to early Jingdezhen ceramic manufacturing techniques.