Multi-analytical investigation into the materials and techniques of paintings on Northern Wei Dynasty (398–494 CE) coffin planks excavated from Shanxi, China

This study combined various non-invasive and micro-invasive analytical techniques to investigate the production process of coffin plank paintings excavated from a Northern Wei tomb in Zhijiabao Village, Datong City, Shanxi Province. Fiber-optic reflectance spectroscopy, portable Raman spectroscopy, and portable X-ray fluorescence spectroscopy were employed for in-situ non-invasive detection of coffin panel paintings. On that basis, micro-samples in smaller amounts than that of previous studies of the same type were collected and analyzed through optical microscopy, confocal micro-Raman spectroscopy, and scanning electron microscopy-energy dispersive spectroscopy. The results showed that the studied coffin plank decoration was painted after applying a layer of yellow primer to the plank surface. Specifically, cinnabar was used as the red material, pararealgar was used as the yellow color, an indigo and orpiment mixture was used as the green substance, the blue pigment was most likely an indigo and lead white mixture, gypsum was used the white material, and carbon black was used as the black pigment. Notably, the studied coffin plank was painted with a mixture of inorganic and organic materials to present the green and blue colors. This study provided not only a scientific basis for the conservation and restoration of this artifact but also new information for the research on Northern Wei art history.