Technological Analysis of Glazed Tiles Unearthed from Bao’ensi in Nanjing

To understand the firing technology and the level of production of glazed tiles in the Ming Dynasty, an ultraviolet-visible-near-infrared (UV-vis-NIR) spectrophotometer and an energy-dispersive X-ray fluorescence (XRF) spectrometer were used to systematically analyze the glaze color and chemical composition of glazed tiles unearthed from the southern area of the Bao’ensi site. The results revealed that little difference exists in the main wavelengths of the same glazed tile samples, but that the colored elements of glaze with different colors are different. Iron (Fe) is the main element that affects the color of yellow glaze; copper (Cu) is the main element that affects the color of green glaze; and the main colorants that affect the color of black glaze are Fe, Cu, and manganese (Mn). The yellow and black glaze unearthed from the southern area of the Bao’ensi site were relatively mature in terms of raw material composition and technological formula, whereas the raw material and technological formula of green glaze were not stable enough. To meet temple construction needs, workers were skilled in firing glazed tiles with different glaze color requirements, indicating that the glaze color of the glazed tiles was relatively mature at that time.