Study on the discoloration and detachment of overglaze-decorated porcelain from the Yangtze Estuary Ⅱ shipwreck

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This study investigates discoloration and detachment of overglaze-decorated porcelain from the Yangtze Estuary Ⅱ shipwreck using a representative sample and SEM‑EDS, XRD, Py‑GC/MS, and 16S rRNA gene sequencing to systematically characterize micromorphology, phase composition, organic matter, and microbial communities in corroded areas. Results show that Pb and As in the glaze confirm famille rose, and the red overglaze was produced with a glass‑white ground layer. Discolored green and red areas contain sulfides (Cu 5 FeS 4 , CuFeS 2 , PbS, FeS) covered by organic films. Microbial analysis indicates that anaerobic sulfur‑cycling bacteria such as Sulfurovum in the burial environment likely contributed to sulfide formation. Unlike the stable single‑layer green enamel, the red composite enamel lost interfacial integrity after corrosion, leading to interlayer disintegration and detachment. These findings clarify the manufacturing technique and the corrosion mechanism driven by microbe‑glaze interactions, offering a reference for conserving underwater‑excavated overglaze-decorated porcelain.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.