The method to soften the concretions of ceramics in the “Nanhai I” Shipwreck of China Southern Song Dynasty (1127–1279AD)

The “Nanhai I” shipwreck of the Southern Song dynasty is the existent oldest and the most integrally preserved shipwreck in the world. Inside the shipwreck most of the ancient ceramics were covered with different types of concretions. In our work, different types of concretions were analyzed using stereomicroscopy, X-ray fluorescence (XRF) and X-ray diffraction (XRD). Based on those analyses, we applied a new physical method of heating and boiling to soften the concretions and remove them from the ceramics. It turned out that this method was efficient to remove the white shellfish concretions, gray concretions and red iron concretions, which not only provided a good basis for the preservation of ancient ceramics of the shipwreck, but also benefited the archaeological research on ancient ceramics.