Corrosion mechanism of a Jingdezhen Qingbai Porcelain from the Nanhai I shipwreck: the ash-green glaze

This study investigates the observed corrosion features and possible degradation pathways of an ash-green glazed Qingbai (bluish-white) porcelain sherd recovered from the Nanhai I shipwreck, which was produced at the Hutian kiln in Jingdezhen. A multi-analytical approach was employed to characterize the chemical composition, microstructure, and phase constitution of the sample. The results reveal that the black-brown contaminants in the glaze cracks were identified as FeS 2 , while the SiO x spheres within the glaze bubbles, some of which possess a well-aligned submicron particle structure, were observed. White spots, arc-shaped cracks, and corrosion pits densely distribute on the glaze surface. We hypothesize that local Mg-bearing environments could have influenced silica alteration. To understand the intrinsic correlation between the corrosion behavior and the original microstructure of the glaze, we provide a fundamental analysis of the processing defects in this specific artifact, referring to traditional Jingdezhen manufacturing techniques.