Abstract:China is the most ancient area of jade culture in the world. With the rise of jadeology, the phase composition of jade and its mechanism of etching have become a concern to the community. In our study, we used scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX), laser Raman microspectrometry (LRS) and Fourier transform infrared spectrometry (FTIR) to analyze four jade fragments from Tomb M88 from the Sujialong Site in Jingshan, Hubei Province as well as one modern Hotan jade sample. In addition to the fibrous mineral components, tremolite jade also contains higher fatty acid salts which exist in a glass phase. The fatty acid salts are distributed as a buffer in the grain boundary and gaps, so that the tremolite has high flexibility and does not break easily. During the etching, fatty acid salts were dissolved out and some were enriched at cracks and loose areas, adsorbing other substances to cause jade to be etched. After the loss of a large amount of fatty acid salts, the internal chains of tremolite are prone to breaking. In this process, the Ca-O and Fe-O bonds in the chain are broken before breakage of the Mg-O bond due to their lower strengths. The actinolite structure is reduced accordingly and the translucent jade turns opaque and is even whitened.

Abstract:Excavation of Tomb M12 at Zhaoxiang, Dangyang, Hubei Province, yielded 459 pieces of ornaments, some of which were covered with gold or tin foil carved with decorative patterns. The decorations were elaborate and fine, featuring smooth lines and the artistic style of Chu. Since excavation, those ornaments have not been subjected to any conservation or restoration, so the fine patterned gold foils were scattered, curled and dirty, and covered with dust and corrosion products. As a result, the function of those metal ornaments was not clear. In our study, we took Bi-shaped gold-wrapped bronze ornaments excavated from the tomb as objects of research. First, we analyzed the bronze body, gold foil and corrosion products of the objects by microscopic analysis, X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and ion chromatography (IC). Then we cleaned off the corrosion products and matched and posted the gold foil. In addition, we rearranged excavation situations of metal ornaments with the same shape as our samples of the pre-Qin period in China, and made a preliminary research on its use scenes.

Abstract:In this work, a mixture of acetone and dimethyl sulfoxide (volume ratio 1∶1) and a particular covering method using degreasing cotton and preservative film was applied to remove the oil paint from the surface of a Zhen’an Temple iron bull. The solvent mixture and the covering method quickly and efficiently removed the oil paint film. The optimum mixed reagent for dissolving the oil paint film was selected by referring dissolution experiment photographs and Fourier transform infrared spectra. Besides, scanning electron microscopy and energy dispersive spectrometry were employed to test the dissolution behavior of the mixed reagent. The mixed reagent could dissolve the oil paint film without harming the iron bull matrix. The concept of "three dimensional solubility parameters" was applied to explain the dissolution action of the mixed reagent. Additionally, the theoretically optimum solvent volume ratio of the mixed reagent could also be inferred using the concept. The covering method and a hair drier were adopted to purge the damp and warped oil paint film after the immersion in the mixed reagent. This thermal drying method could quickly blow off the paint film from the surface layer of the Zhen’an Temple iron bull with a good effect.

Abstract:The no.8 Grave at Chengyangcheng Site, located in Xinyang, Henan Province, is a noble tomb of Chu State during the late Warring States Period. More than 400 pieces of lacquer and wooden wares were excavated from the tomb, of which a lacquer-bamboo mat woven with black and red bamboo strips was the most exquisite. In order to understand the production process and to carry out the research on protection from dehydration of the painted bamboo mat, the composition and surface morphology of the bamboo mat lacquer film were analyzed using laser confocal microscopy, Raman spectrometry, Fourier infrared absorption spectrometry and scanning electron microscopy-energy dispersive spectrometry. The results show that the black color of bamboo mat lacquer film is the natural color of lacquer, and the red one is the color of lacquer mixed with vermilion. The surface of the black lacquer film is smooth and has a tight combination with the bamboo body, whereas the surface of red lacquer film is rough and its structure is loose. The lacquer film is between 0.02 and 0.03 mm thick, and is thought to have been formed by brushing with lacquer three to five times, based on simulated lacquer films.

Abstract:Painted clay figurines in the Thousands of Buddha Hall of Chongqing Temple in Zhangzi County, Shanxi Province, have been gilded to varying degrees. Coatings on the gilded surfaces had aged and turned brown, but it was feared that cleaning using existing technologies might damage the gold leaves. In order to solve the problem, samples taken from the back light positions of Sakyamuni were analyzed by cross-section microscopy, scanning electron microscopy and infrared spectrometry. The results show that the original coatings had curled and peeled off, and that the remaining component was raw lacquer. Based on these results, tests were conducted to find a suitable agent for cleaning the coating; NYC solution was screened. The solution dissolved the coatings and then rice paper was used to absorb liquid on the surface of the figurine. The whole process was gentle and did not damage the gold leaves.

Abstract:In this paper, the late Qing elm wood residential buildings at Yunshan Village, Zuoba Town, Dayu County of Ganzhou, Jiangxi Province were utilized as research objects for protection studies. The coating technology for the ancient elm wood buildings in this area was studied in terms of molecular design of new fluorosilicone acrylic resin materials, coating agent formula and coating process optimization. The results show that the fluorosilicone acrylic resin coating agents prepared by multi-component copolymerization of monomers such as dodecafluoroheptyl methacrylate, 3-methacryloxypropyltrimethoxysilane and other acrylates have good chemical corrosion and weather resistance, hydrophobic and oleophobic properties, bacteriostatic activity, ultra-thinness, high light transmittance (no reflection) and flame retardancy. Traditional coating processes can be adopted for the coating agents, and coating and film-forming processes do not emit toxic and harmful substances. These materials can effectively coat the surface of the wood material fiber microstructure, and also effectively protect the elm wood structures of ancient buildings without changing their appearance.

Abstract:Some studies have shown that compared with traditional drying technologies, supercritical CO₂ technology has some advantages, such as a shorter drying time, smaller deformation, etc. Compared with unearthed waterlogged bamboo and wood wares, undersea wooden cultural relics contain more insoluble salts. In the case of long-term preservation and exhibition of cultural relics, the chemical reactions of salts with water, air or the cultural relics themselves will accelerate the aging and corrosion of the cultural relics. In this research, some components from Nanhai Ⅰ shipwreck were taken as the research objects. The experimental results show that under the conditions of 40 ℃ and 20 MPa, the effect of supercritical CO₂ fluid drying on the undersea wooden cultural relics was obvious in that the three-dimensional shrinkage of the samples was lower than or close to those of the healthy wood. After drying, the water content met the requirements of cultural relic preservation and the salt content of the samples also decreased significantly.

Abstract:Among the relics related to the coin casting of the Han Dynasty, the quantity of the clay-gravel molds is the largest. These consist of a clay surface layer and a clay backing layer mixed with much gravel. The surface layer was made from clay and plant ash to improve the quality of coins. The backing layer was made of clay and gravel to improve its mechanical properties and decrease the deformation of mold after firing. The production process was as follows:first, a backing layer was made of clay and gravel; second, a thin fine clay layer was made on the back as a surface layer; then the back pattern cavities of coins were made on the fine clay layer using a model. After being used for casting metal coins, the surface layer would be damaged by molten metal. A new thin layer could be made directly on the underlying surface or after the removal of the previous surface layer. The backing layer could be used many times until it broke. As a result, the production efficiency for casting bronze coins was improved.

Abstract:In order to distinguish waxes used in cultural relics and used as conservation or restoration materials for cultural relics, online-methylation pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was applied to analyze beeswax, carnauba wax, candelilla wax, ozokerite and paraffin wax. It is found that 1) the main pyrolytic products of beeswax are straight-chain alkanes, straight-chain fatty acids, straight-chain alcohols and fatty acids with hydroxyl groups; 2) those of carnauba wax are straight-chain alcohols, straight-chain fatty acids and fatty acid derivatives; 3) those of candelilla wax are straight-chain alkanes, straight-chain fatty acids, straight-chain alcohols, lupeol and its derivatives, germanicol and its derivatives and fatty acid derivatives; 4) those of ozokerite and paraffin wax—mineral waxes—are both straight-chain alkanes. Different waxes could be distinguished since the kinds and relative contents of pyrolytic products in each wax are different. The established Py-GC/MS procedure and summarized data were successfully applied to the identification of beeswax and mineral wax used for the inlaying enamel in a Qing table screen with a rosewood frame, inlaid jade figures and a wengewood carved landscape collected in the Forbidden City. The method of our present work is easy for the spreading and applicable to the accurate and rapid identification of waxes used in cultural relics.

Abstract:The Tibetan Tripitaka is a collection of the Tibetan versions of Indian Buddhist classics and writings, and is of high historical, scientific and artistic value. In this work, optical microscopy (OM), scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX), Raman spectrometry, high performance liquid chromatography-mass spectrometry (HPLC-MS), microbial purification & cultivation technology, molecular biology identification technology and high-throughput sequencing method were applied to a sample (S1) Tibetan Tripitaka paper with gold writing and 2 samples (B1 and B2) coated with microorganisms of the Ming and Qing Dynasties. It was found that 1) the gold writing material is particles of a gold-silver-copper alloy containing Au (72.8%—75.6%), Ag (22.8%—26.0%) and Cu (1.2%—1.6%), indicating a relatively low purity of gold mud used; 2) paper was dyed with indigo, coated with graphite; 3) pH value is 7.0—7.5, suggesting that it has not been acidified and 4) a large number of fungal spores scattered among paper fibers. The microbial secretions are one of the main causes of paper adhesion during the preservation. The results of microbial purification and cultivation and molecular biology identification show that the green mold on the surface of Tripitaka Sample B2 is Aspergillus fumigatus. The high-throughput sequencing results show that the microbial species attached to the surface of Tripitaka Sample B1 included Chaetomium sp., Aspergillus sp., Mucor sp. and Beauveria sp., etc.

Abstract:The chromogenic copper and arsenic-containing green and blue-green pigments of rock carvings at Big Buddha Bay in Dazu, Chongqing, were investigated and analyzed using portable X-ray fluorescence spectrometry (XRF), portable microscopy and other non-destructive analysis methods in combination with X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX), X-ray photoelectron spectrometry (XPS) and micro Raman spectrometry (RM). The results show that the chromogenic component of the green pigment is emerald green , and that of blue-green pigment is lavendulan [NaCaCu₅(AsO₄)₄Cl·5H₂O]. Also, it is inferred that lavendulan is a discoloration product of emerald green, based on this research. This work provides new clues to and methods for research on the chromogenic changes in modern synthetic pigments.

Abstract:Fengguo Temple in Yixian County is part of the royal monastery of the Liao Dynasty. The Grand Hall, the main hall of the temple, is a Liao building, the walls of which are full of murals of a grand scale and unique drawing techniques. It is of great value for the study of murals of the Yuan Dynasty. However, due to the serious damages caused by war, earthquake and other disasters, the preservation status of murals is quite worrying. Because of the difficulty in protection and the unclear mechanism research, it is impossible to carry out physical protection and restoration at present. Therefore, we tried dealing with the diseases of mural lines, pigments and structures in a virtual way using Photoshop. The contents of the virtual restoration include cleaning the mural surface covering, completing the missing parts of lines and colors, and correcting the discolored and faded areas. The results show that the restoration of the image has achieved good effects. Photoshop virtual restoration is a feasible and effective method for mural protection. It can not only provide references and lessons for subsequent physical protection, but also extract the value of murals to the greatest extent and be conducive to the display.

Abstract:Here we describe the study of the seismic behavior of the bridgehead of Nanjing Yangtze River Bridge after the strengthening of its infilled walls. In this study, we proposed a double-strut model in consideration of the cracked higher infilled walls for rare earthquake analysis. In addition, an accurate approach to simulating the structure after the strengthening of the infilled walls was also developed. Using SAP2000, structural computing models used for the analysis of frequent earthquakes, fortification earthquakes and rare earthquakes were established. The seismic behaviors of the bridgehead structure before and after the strengthening of the infilled walls were compared. Furthermore, in order to study the seismic response of the bridgehead, a real earthquake happening in 1974 was introduced in the analysis and compared with the El-Centro wave. The study results showed that 1) the seismic behavior of the bridgehead after the strengthening of the infilled walls was improved remarkably. The peak value of displacement responses decreased by 8%~23% and the inter-story displacement angle responses decreased by 12%~22%; 2) the inter-story displacement angles in the X direction and the Y direction both met standard requirements under fortification earthquake action; 3) the cracking of the infilled walls in the rare earthquake reduced the torsional stiffness of the bridgehead structure, but it was improved after the infilled walls were strengthened, which, therefore, avoided the torsional vibration of the structure in the earthquake effectively. Furthermore, the difference of the results using two different earthquake waves was about 3%~21%, and the positions of the peak responses of the bridgehead were a little different. Thus, it is suggested that more than one earthquake waves should be selected to analyze the seismic behavior of a bridgehead structure. The study results could provide a reference for the seismic strengthening of similar historical reinforced concrete buildings.

Abstract:A non-destructive analysis method was established for the determination of volatile substances in folding cases using thermal desorption-gas chromatography/mass spectrometry. Tenax-TA tubes were used for the absorption and desorption of 10 target compounds. Under optimized chromatographic conditions, benzene, toluene, n-butyl acetate, ethylbenzene, m-xylene, p-xylene, styrene, o-xylene, n-undecane and furfural had good linear correlations. Samples in the laboratory were also obtained and analyzed. The results show that separation analysis of volatile hazardous substances can be achieved using this method.

Abstract:Different from corrosion products on freshly excavated bronzes, pale blue copper corrosion products have often been observed on metal objects in museum collections. These were identified by a combination of scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX), X-ray diffractometry (XRD) and Raman spectrometry as copper organic salts including simple (or basic) copper acetate and copper formate, as well as some complex compounds such as sodium copper carbonate acetate NaCu(CO₃)(CH₃CO₂) and sodium copper formate hydroxide oxide hydrate Cu₄Na₄O(HCOO)₈(OH)₂·4H₂O. The formation of this type of copper corrosion product was caused by poor environment of display or storage and/or residual chemicals used in previous conservation treatments. To prevent formation of these compounds, the objects need to be displayed or stored in an organic acid-free environment with controlled low relative humidity. Chemicals used for conservation treatment should completely be removed from the objects to prevent further deterioration. One needs to be especially cautious to treat and preserve objects with composite materials, as different environmental conditions are required for the safe preservation of different materials. For this reason, such objects should be treated and preserved on a case by case basis.

Abstract:Freeze drying is one of the main consolidation methods used to stabilize unearthed/salvaged waterlogged wooden archaeological artifacts. This method is based upon the sublimation of ice, thus no surface tension is produced and the damage to woods by drying stress is avoided. For decades, the freeze drying technology for unearthed/salvaged decayed woods containing salts has been improved through experiments and practice, and better stabilization and consolidation of archaeological artifacts have been obtained. Great improvements have been made both domestically and overseas in terms of desalting technology, impregnation materials and protocols, pre-cooling and sublimation drying. The development of relevant specialized equipment is now being undertaken with application of nondestructive monitoring.