X-ray fluorescence spectroscopy, scanning electron microscopy energy spectrum, excitation-emission matrix spectroscopy, and Fourier transform infrared spectroscopy was applied to the unearthed jade with multilayered corrosion, to reveal the microstructure, composition structure, and distribution of organic matters. Our results showed that the interior of the jade was mainly composed of layered serpentine with a regular structure, while the white layer structure on the surface is scattered and irregular, and the content of calcite formed by elements Ca and C increases significantly; between the green matrix and the white layer on the surface, there are brown corrosion zones with obvious fluorescence effect and mainly composed of humic acid, which continuously extends inward along the corrosion cracks for accelerating the internal corrosion. This article, for the first time, argued for the corrosive and fluorescent humic acid bands that appear inside serpentine jade and cautions its role in investigating the corrosion of jade.
Natural aging plays a key role in the degradation of proteinaceous binders which are important dispersers and stabilizers of painting layers. Knowledge about the natural aging influence on the stability of binders is important for exploring the deterioration mechanisms of painted artworks. Pig glue, whole egg, egg white, egg yolk, casein, and mixtures with ultramarine were aged for 10 years in natural conditions. GC-MS and FTIR were applied to explore the changes in the binders at a molecular level. Our experiment revealed that the less stable Met (Methionine), Lys (Lysine), Ile (Isoleucine), Ser (Serine), Asp (Aspartic acid), Glu (Glutamic acid), Hyp (Hydroxyproline), especially aromatic Phe (Phenylalanine), and Tyr (Tyrosine) were damaged, thus the contents of the stable Ala (Alanine), Gly (Glycine), Val (Valine), Leu (Leucine), and Pro (Proline) increased. The broadening of Amide A and the declining amount of α-helix, along with the increasing contents of β-sheet and random coils, all showed that the binders had transformed into disordered states. What is more, we found that pig glue had better natural aging resistance, ultramarine could speed up the aging process and lipids in egg were more easily degraded. The mechanisms of the changes of primary structures and secondary structures are also discussed in the paper.
Once excavated, cultural relics face immediate threats from oxidation, water loss, mold growth, etc., which are caused due to severe environmental changes. Covering with plastic films, spraying water, or applying biocides followed by mechanical polish are common conservation practices, which are effective to some extent, but with obvious side effects. Menthol, often used as volatile binding material (VBM) in heritage conservation, has been proved to be safe to conservators and cultural relics and can be removed easily via sublimation with no residue. In this study, the possibility of using menthol coatings as a reversible environmental barrier to protect cultural relics during excavation is examined. Laboratory results show that menthol coating has an excellent ability to prevent oxygen and water molecules from passing through it, to stop various fungal growths and cut off radiation below 300 nm. On-site antifungal applications on a mural tomb of the Tang Dynasty, located in the north of Xi’an Xianyang International Airport, provided satisfactory results. Laboratory and field results show that menthol coating has high potential of being used for the emergency protection of relics against sudden environmental changes during excavation.
As one of the common physical materials in Chinese archaeological excavations, ancient bronzes are important bases for studying the development of Chinese bronze culture, which is of great significance for exploring the development law of ancient human culture and reconstructing ancient human society. However, the ancient bronzes unearthed by archaeological excavations have been corroded to varying degrees under the dual influence of the soil burial environment and the sudden change of the above-ground environment, which has led to the different health status of the cultural relics. An adequate scientific evaluation of these bronzes is needed to inform how they should be extracted, moved and transported, as well as how subsequently they should be restored. Based on the analysis and research of relevant industry standards and the disease characteristics of bronzes to determine the risk factors affecting the health status of unearthed cultural relics, and then determines the main content of the health assessment of bronzes. By studying methods to effectively characterize the health status of bronzes and combining laboratory research to form a systematic method for in situ nondestructive analysis of bronzes. Through the systematic analysis of the detection results of the evaluation indicators to establish an analysis model for the health evaluation of bronzes. Finally, this paper achieves a scientific and effective evaluation of the health status of bronzes unearthed from archaeological sites. This enabled the feasibility of the extraction methods to be evaluated using the excavated Sanxingdui bronzes as samples.