Study on the Chemical Composition and Lead Isotope Ratios of Lead Glaze Used on Blue Tiles from Gyeoungbokgung Palace

Composition analysis and lead isotope ratio analysis were conducted to determine the coloring machanism on lead glaze used in Gyeongbokgung Palace and the provenance of the lead used as a flux.31 blue tiles were classified into green, blue, and yellow.The chemical analysis of lead glazes on the blue tiles revealed that Pb, Si, and Cu were the main components, and trace amounts of Fe, Ca, Mg, and Al were detected.The Cu content was high in blue lead glaze, while Cu was not detected in yellow or brown lead glaze which instead had high Fe content.Therefore, it was found that lead was used as a flux and copper oxide as a coloring agent in the production of lead glaze.In addition, the lead isotope ratios of the lead glaze used in the blue tiles of Gyeongbokgung palace were plotted in zone 3 on the distribution map of lead isotope ratios on the Korean Peninsula, which includes Chungcheong-do and Jeolla-do.It is presumed that the flux for the lead glaze was sourced from galena found in these regions.The lead isotope ratios of the green glaze from the Three Kingdoms and Unified Silla period were mostly located outside the Korean Peninsula, showing that the provenance of lead had changed.In particular, the lead isotope ratios of the green glaze from the Three Kingdoms and Unified Silla period suggest exchange with neighboring countries.Also the lead isotope ratios of the green glazes from the same temple are different, so it is believed that they were made at different times or in different workshops.