In situ analysis of pigments on the murals of Yanshan Temple in Fanshi County, Shanxi Province, China by portable Raman and XRF spectrometers

The murals of the Yanshan Temple can reflect the social life in the Song and Jin Dynasties, which are of great significance to the study of the social history, religious culture, and architectural features of the Song and Jin Dynasties. These exquisite murals are one of the few existing murals of the Jin Dynasty (1115–1234 AD) in China, which have important historical, cultural and artistic values. In this research, a portable Raman spectrometer and a hand-held X-ray fluorescence (XRF) spectrometer were used to carry out the in-situ nondestructive measurement on the pigments of the murals in the Yanshan Temple. The pigments used in the murals were successfully identified, including cinnabar, red lead, calcium carbonate, gypsum, anhydrite, lead sulfate, carbon black, massicot, azurite, malachite, and chromium oxide. Among them, calcium carbonate and gypsum are considered as ground layer materials. Lead sulfate was detected in the grayish-purple and red areas, along with red lead. It is speculated that lead sulfate is the degradation product of red lead. Chromium oxide found in one dark green area is a modern pigment synthesized in the early 1800s. Therefore, it can be inferred that this dark green area has been restored in modern times. This study makes up for the deficiency of research on the murals in Yanshan Temple and provides scientific guidance for the protection and restoration of the murals in the future. Graphical abstract