Revealing the surface treatment techniques and degradation characteristics of textiles from a set of thangkas of the mid-Qing Dynasty (1776–1839 CE).

In this paper, X-ray microtomography, scanning electron microscopy - energy dispersive spectroscopy, second harmonic generation imaging microscopy, Fourier transform infrared spectroscopy, and X-ray diffractometry were combined for the scientific examination of the surface treatment techniques and degradation characteristics of hemp textiles from six mid-Qing thangkas. The results showed that kaolinite was added as a filler in the production of the canvas, and the fiber morphology and molecular structure of the six hemp thangka textiles were disparate from those of fresh hemp. Specifically, the canvas fiber surfaces were rough, with twisting, deformation, fracture, and decreased cellulose crystallinity indexes. Those results indicated that all six thangkas had undergone significant degradation, which was relatively severe in samples TK16 and TK18. By complimentary evidence derived from the above analyses, the information on the production techniques and degradation degrees of this group of precious thangkas were obtained, thus enabling the accurate assessment of the preservation status of the thangkas and providing a scientific basis for its conservation and restoration. [ABSTRACT FROM AUTHOR]