Multi-micro analytical studies of blue-and-white porcelain (Ming dynasty) excavated from Shuangchuan island

Shangchuan Island lies in the southern part of the Guangdong Province in China. Historically it is considered as an important berthing wharf of the South China Sea for the Maritime Silk Roads, witnessing the early Sino-Portuguese trades. Related research on the cultural relics in the region has attracted significant attention from archaeologists. In this study, blue-and-white porcelains excavated from Shangchuan Island were analyzed by multi-micro analytical techniques. In-glaze decoration and under-glaze decoration processes were suggested for the glaze painting process, as revealed by digital microscopy. Silica-aluminum system with flux agents of calcium, potassium and sodium, as well as the main elements of blue pigment with iron, manganese, cobalt and nickel, were found by analysis of micro X-ray fluorescence spectrometry. By calculating the discriminate functions (F) for the chemical compositions of porcelains body, as well as the S-i value for porcelain glaze, the origin of these blue-and-white porcelains were identified with the origin of the Jingdezhen kiln in the Ming dynasty. Anorthite (CaAl2Si2O8) crystals were observed in glaze layer of porcelain by micro-Raman spectroscopy, as well as a-quartz (SiO2) and calcite. These archeological evidences not only helped to understand the history of the early Sino-Portuguese relations, but also proved the important historical status of Shangchuan Island and contributed to the study of the history of Chinese ancient Maritime Ceramic Road.