Reconstructing the firing process of pottery from dangxiong cemetery, Tibet, China: Estimating soaking time through XRD and thermal expansion analyses

Abstract

A comprehensive analytical study was conducted, encompassing refiring experiments, X-Ray Diffraction (XRD) and thermal expansion analyses, to investigate the firing temperature and soaking time of pottery sherds found in Dangxiong Cemetery, China. The results established that the thermal expansion technique could precisely determine the lower limit of the pottery's equivalent firing temperature. Furthermore, a linear relationship between the mineral content of refired samples and the soaking times during refiring experiments was established, enabling accurate estimation of the soaking time of the pottery's original firing. The maximum firing temperature of some pottery sherds excavated from the Dangxiong cemetery exceeded 900 °C, and they maintained this temperature for a period of time not exceeding 20 min, indicating that these pottery sherds were probably fired in a structure without heavier insulating materials. This study, for the first time, illustrates the significant potential of combining XRD with the thermal expansion method in assessing the soaking time during the firing process of ancient pottery.