Studies on wall painting materials and techniques at two historic buildings in Gyantse, Tibet

Abstract

This paper presents a scientific examination of wall paintings at two nonmonastic sites in Gyantse, Tibet: Gazhi Lhakang, which is a family temple built in the mid-eighteenth century by local aristocrats, and the Lotso Residence, which was occupied by Nepalese merchants in the early twentieth century. Samples were analyzed with optical microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, Raman spectroscopy, and X-ray diffraction. Two phases of painting—an early phase and a late phase—were identified in Gazhi Lhakang, including three distinct types of mural stratigraphy. The earlier phase features an unusual technique known as “paperhanging”, wherein the pigments were applied on a layer of Tibetan paper glued to the wall. The later phase at Gazhi Lhakang and the painting of the Lotso Residence feature a relatively simple wall treatment with fewer coating layers and no ground layer. A typical mixture of clay and sand was used for the coating layers, while the structure slightly varied from what has been described in the literature. The techniques of powder embossing, gilding, and gold outlining were adopted in both buildings. The metallic material found at Gazhi Lhakang is a gold-silver alloy, while copper was used as imitation gold at the Lotso Residence. Mineral pigments, such as azurite, malachite, orpiment, cinnabar, and iron oxide, were used for both phases of Gazhi Lhakang. Modern synthetic pigments, such as chrome yellow, emerald green, and synthetic ultramarine, were used for the Lotso Residence, indicating that it was painted after the mid-nineteenth century.