In-Situ Non-Invasive FTIR Analysis of Conservation Materials on the Surface of Mural Paintings in Prince Shi’s Palace of the Taiping Heavenly Kingdom
WANG Zhuo1, 2, SU Bo-min1, 2*, YU Zong-ren1, 2, SHUI Bi-wen1, 2, ZHAO Jin-li1, 2, CUI Qiang1, 2, SHAN Zhong-wei1, 2, LI Qian3
1. National Research Center for Conservation of Ancient Wall Paintings and Earthen Ruins, Dunhuang 736200, China
2. Key Laboratory of Gansu Province for Conservation of Ancient Wall Paintings and Earthen Ruins, Dunhuang 736200, China
3. Prince Shi’s Palace of the Taiping Heavenly Kingdom Memorial Museum, Jinhua 321000, China
Abstract：The murals in Prince Shi’s Palace of the Taiping Heavenly Kingdom are the typical examples of the murals in southern China, which have important historical, cultural and artistic values. In history, chemical conservation was carried out on many murals, and part of the murals formed a certain thickness of organic coating on the surface. It is of great theoretical and practical significance to analyze and study the compositions of mural conservation materials for the protection of cultural relics. Due to the rarity and non-renewability of cultural relics, the research and application of in-situ non-invasive analytical technique will be the trend in the future. Reflection infrared spectroscopy based on portable infrared spectrometer is an ideal method for non-invasive analysis of surface materials of cultural relics. In this paper, reflection Fourier transform infrared （FTIR） spectroscopy was used to analyze ground layer and conservation materials of murals in Prince Shi’s Palace, and it is the first time that this method was applied to the analysis of ancient Chinese murals and their conservation materials. In this study, the reflection FTIR spectrum of uncoated mural’s white background was measured at first, and the compositions of ground layer were identified as calcite and gypsum by comparison with standard inorganic minerals by reflection FTIR spectra. On this basis, the infrared reflection features of uncoated and coated mural surfaces and the influence of ground layer on surface coatings were analyzed. The feasibility and applied range of using Kramers-Kronig （K-K） transform as a data processing method were discussed. The differences between K-K-transformed reflection spectra and attenuated total reflection （ATR） spectra of mural coatings were analyzed. The reliability of in-situ reflection FTIR spectroscopy was verified by microscopic ATR FTIR spectroscopy and pyrolysis-gas chromatography/mass spectrometry（Py-GC/MS）. The thicknesses of coatings were measured by scanning electron microscopy（SEM）, demonstrating that high-quality reflection FTIR spectra can be obtained for different thicknesses. Finally, it was confirmed that the murals in Prince Shi’s Palace were strengthened with three kinds of polymers: polyvinyl acetate, polydimethylsiloxane and acrylic resin, and it was concluded that the current preservation situations of murals are closely related to conservation materials and coating thicknesses. The above research proves that the information of organic compounds and some inorganic substances on the surface of cultural relics can be effectively obtained by reflection FTIR spectroscopy. This method is particularly sensitive to organic coatings on the surface, making it an ideal non-invasive analytical method for cultural relics of mural paintings, and it has a very broad application prospect in the field of mural conservation research. Meanwhile, this study makes up for the deficiency of in-situ non-invasive analysis of organic compounds on the surface of Chinese murals, and provides a new idea for the research in this field.
王 卓，苏伯民，于宗仁，水碧纹，赵金丽，崔 强，善忠伟，李 倩. 太平天国侍王府壁画表面修复材料的原位无损FTIR分析[J]. 光谱学与光谱分析, 2020, 40(02): 356-361.
WANG Zhuo, SU Bo-min, YU Zong-ren, SHUI Bi-wen, ZHAO Jin-li, CUI Qiang, SHAN Zhong-wei, LI Qian. In-Situ Non-Invasive FTIR Analysis of Conservation Materials on the Surface of Mural Paintings in Prince Shi’s Palace of the Taiping Heavenly Kingdom. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2020, 40(02): 356-361.
