Abstract:The high moisture content of excavated ivories excavated from Sanxingdui sacrificial pits is due to their long-term burial in the wet underground environment. There are also such problems as body fracture, glaze cracking and peeling, resulting from poor preservation conditions. It is very easy for excavated ivories to lose water quickly and suffer irreversible damages such as cracking and pulverization. To clarify the preservation status of excavated ivories from Sanxingdui site, the composition, structure and water loss process of ivories at Pits No.3,4, 7 and 8 (K3, K4, K7 and K8) of Sanxingdui site excavated in 2021 were analyzed by means of spectrometry, electron microscopy and nano-indentation, etc. The results show that the main phase of the excavated ivories from the four sacrificial pits was hydroxyapatite [Ca₁₀(PO₄)₃(CO₃)₃(OH)₂]. The organic components had largely disappeared, forming a mainly mesoporous pore structure (pore size distribution in the range of 3-50 nm). These pore structures were occupied by a large amount of adsorbed water and bound water, showing high adsorbent water contents. The moisture contents of K3-excavated ivory (K3XY-54) and K4-excavated ivory (K4YW-289) were 43.8% and 43.4%, respectively. All the four sacrificial pits had flake and needle-like crystal structures, among which, K3XY-54 showed obvious orientation growth with needle-like crystal structures, while K4YW-289 showed crystal aggregation and significant increase in thickness. The internal stress of microstructure caused by the volatilization of adsorbed water on the surface and inside of excavated ivories, resulted in irreversible damages such as cracking and pulverization. The surface micro-hardness changes of excavated ivories in the rotten state were preliminarily explored by nano-indentation. The surface micro-hardness difference of K4YW-289 before and after water loss was the largest (0.090±0.049 GPa in the waterlogged state, 1.55±0.31 GPa after water loss), which may be related to the low adsorbed water content in the component structure and high argillation phenomenon. In combination with the studies of K3XY-54, K7XY-43 and K8XY-11-13, it was found that the micro-hardness and elasticity modulus of excavated ivories before and after water loss was largely affected by the relationship between the component structure and water loss rate. These research results provide a powerful scientific basis and reference data for the subsequent effective implementation of preservation and reinforcement of excavated ivories.

Abstract:Liujiawa site in Chengcheng County, Shaanxi Province was the capital site of Rui State in the Spring and Autumn Period. Its discovery and excavation provides a typical case of the development and evolution of the vassal states of the Eastern Zhou Dynasty, which is of great significance to fill in the blank of the late history of Rui State and promote the Zhou-Dynasty archaeological development of the eastern Guanzhong region. Wooden lacquerwares unearthed at Liujiawa site are mainly related to musical instruments. Most of their wooden bodies have been corroded and only lacquer films remain (most are broken and rotten). Current research has initially explored suitable conservation materials for the unearthed rotten lacquerwares from north China, but research on evaluation methods for the conservation effect is limited, and there are also some challenging puzzles, such as low instrument precision and large dispersion of test data. To evaluate the conservation effect of several commonly used acrylate emulsions which were difficult to distinguish in previous research, this work was carried out to select the optimal conservation material and concentration and study the process sequence. The commercial acrylate emulsions AC33, B60A, MC76 and SF016 are commonly used as consolidants for fragile archaeological lacquer films. However, due to the limitation of preservation conditions and sampling restriction, the reinforcement effects of these acrylate emulsions on lacquer films, especially the essential mechanical properties, have not been assessed (due to the lack of suitable test method). Here, the bending strengths of archaeological lacquer films before and after consolidation were tested by thermomechanical analysis (TMA) with its excellent characteristics of being nondestructive and accurate. According to the degree of improvement of the stress-strain of the treated lacquer films, the reinforcement effects of the four acrylate emulsions were quantitatively evaluated. In combination with the scanning electron microscopy to observe the changes of holes and fissures on the surface and the section of lacquer films before and after reinforcement, as well as the film-forming situation of the four acrylate emulsions, their conservation properties were demonstrated. The results show that the stress of the treated lacquer film increased by 56%-3 511%, and the strain increased by 103%-3 876%. Among the four acrylate emulsions, 20% AC33 had the best reinforcement effect and 20% B60A had the best toughening effect, but MC76 and SF016 performed relatively poorly. 20% is the best concentration for the four acrylate emulsions, in that at this concentration the holes and fissures of lacquer films were completely filled and the acrylate emulsions were able to form a continuous film without excessive accumulation. Compared with previous research, this study has made expansions in the following two aspects:1) a new instrument for the study of rotten lacquer film is proposed—thermomechanical analyzer was used for the first time to test the residual mechanical strength of extremely fragile archaeological lacquer film and evaluate the mechanical enhancement effect of reinforcement agents; 2) a new characterization method to study fragile archaeological lacquerware is initially established—the penetration and film formation of reinforcement agents, surface and profile morphology of the lacquer film and mechanical strengths before and after reinforcement, were systematically studied. This research successfully evaluated the conservation effect of four commonly used acrylate emulsions, which were previously difficult to distinguish, to select the optimal concentration for use, providing a new evaluation method and an important reference for the scientific selection of materials for the conservation and restoration of rotten archaeological lacquerwares.

Abstract:Indo-Pacific glass beads, also known as Indo-Pacific monochrome drawn glass beads, are the glass beads with the longest duration and widest geographic distribution in ancient times. These glass beads are one of the most important markers for the study of the Silk Road exchange and interaction, and have important research values and academic significance for the construction of trade and exchange networks under the global perspective. At present, there are few reports on the scientific research on Indo-Pacific glass beads excavated in China either at home or abroad. The spatial and temporal distribution of such glass beads in China is still unclear and lacks systematic research. Located in Pubei County, Qinzhou, Guangxi Zhuang Autonomous Region, the city of Yuezhou was originated in the Song Dynasty (420 AD-479 AD) of the Southern Dynasties and was abolished in the Sui Dynasty (581 AD-618 AD), lasting for about 140 years. During the Southern Qi period (479 AD-502 AD), Yuezhou governed twenty prefectures (Jun), and occupied an important position in the map of the Southern Dynasties. At the city site, a large number of samples, such as pottery, porcelain, ironware and glass beads, etc., have been unearthed. Among them, there are more than 2,000 glass beads in a variety of colors, including red, blue, yellow, green and brown. In our research, five typical types of glass beads excavated from the city site of Yuezhou were selected, including opacified brownish-red, opacified orange, opacified yellow, translucent light green, and translucent blue-green ones (five samples for each type and 25 samples in total). Energy dispersive X-ray fluorescence spectrometry, confocal laser Raman spectrometry, optical coherence chromatography, and optical microscopy were used to analyze the selected glass beads. The test results show that the glass beads analyzed were mainly made by the drawing process, and the coloring process adopted was mainly of three types:transition metal element (Fe, Cu) ion coloring, metal (Cu) particle coloring and compound (lead stannate) coloring. The major glass system was mineral alkali type sodium-aluminum-silicate glass (mNaAl), and a small number of samples were soda glass. We further compared the contents of the trace elements Sr and Zr with the research results of other scholars, and it is clear that the mNaAl glass beads unearthed from the city site of Yuezhou belong to Subclass 1 of mNaAl glass. Their primary glass provenance was South Asia, and they might have been exchanged to Southeast Asia in the form of primary or finished glass beads and also imported into Lingnan region of China through the Maritime Silk Road. This research clarifies the coloring mechanism, forming process, glass system and subclass characteristics of the glass beads excavated from the city site of Yuezhou, and also the possible origin sources and spread routes based on the Maritime Silk Road, thus providing new physical evidence for the study of the Silk Road-based exchanges between China and foreign countries in southern China from the Wei Dynasty to the Southern and Northern Dynasties, and a new “link point” for the construction of global trade and exchange networks of Indo-Pacific glass beads.

Abstract:Puzhao Temple is located in Hancheng, Shaanxi Province. There are five exquisite painted clay sculptures of the Yuan Dynasty in the temple. In order to understand the materials and techniques used for the sculptures, optical microscopy, X-ray diffraction, micro-infrared spectrometry, micro-Raman spectrometry, scanning electron microscopy-energy dispersive spectrometry and X-radiography were used for scientific analyses. The results show that 1) the sculptures were repainted; 2) the internal structure was a cross wooden skeleton; 3) the mineral compositions of the soil in the coarse and fine clay layers were basically the same, with the soil featuring high strength, strong weathering resistance and good plasticity; 4) the coarse clay-reinforcement materials were wheat straw and wheat husk, and the fine clay-reinforcement materials were cotton and hemp; 5) the coloration components of the pigment layer were common mineral pigments seen in ancient murals, except for the blue one. These research results may provide a scientific basis for the follow-up conservation and restoration of the painted clay sculptures at Puzhao Temple, and also scientific information for the study of the traditional techniques for Yuan Dynasty painted clay sculptures in Shaanxi.

Abstract:Aqueous-phase deacidification is a commonly used method for paper deacidification. However, it easily leads to the diffusion of handwriting (ink smearing/running), especially water-soluble handwriting, which has always been a difficulty in academic and industrial research. In our research, the wettability of papers and the diffusion properties of writing pigments were studied in detail, the anti-diffusing safety of papers and pigments in the process of deacidification was discussed, and the concept of diffusion critical moisture capacity was proposed. The results show that the diffusion critical moisture capacity is directly related to the solubility of writing pigments and the wettability of paper fibers:the better the water solubility of pigments and the wettability of paper fibers, the smaller the diffusion critical moisture capacity. The mist deacidification method has the characteristics of precisely adjustable amount of humidification and uniformly distributed small size of droplet particles. This method can accurately control the amount of deacidification agent according to the wettability of paper (k value) and the solubility of writing materials, in order to avoid the diffusion of handwriting. This work provides a feasible method for paper deacidification with good safety, and a scientific basis for the development and use of deacidification equipment.

Abstract:Guangyuan Thousand-Buddha Grottoes are of great value in researching the spread of Buddhism in China. To explore a scientific evaluation method for the degree of deterioration, we selected 20 grottoes of the middle Tang Dynasty in Guangyuan Thousand-Buddha Grottoes as survey objects. The traditional deterioration investigation was made and the analytic hierarchy process (AHP method) was applied to build a system to calculate the weights of 15 common types of deterioration and to evaluate the degree of deterioration of the grottoes. The result shows that each of the 15 types of deterioration has its own weight on affecting the preservation condition of the grottoes and that it could be classified into two categories—structural deterioration and the non-structural deterioration. By contrast with the realistic condition, the calculation result could reflect the preservation condition of the grottoes quantitatively. The result offers a quantitative basis to determine the priority order of grotto conservation, and verifies the feasibility of the AHP method in helping the conservators identify the major types of deterioration or judging the order of conservation. The research proposes a quantitative evaluation method for the degree of deterioration of grottoes, which could lay a foundation for further conservation of grottoes.

Abstract:The statues of Shuchengyan Rock in Dazu were carved on a whole sand stone and are sheltered and protected by pseudoclassic architecture, but the rock surface, which is covered with a thick layer of dust, has begun to pulverize and peel off. With the help of analytical methods, including X-ray diffraction (XRD), X-ray florescence (XRF) spectrometry, scanning electron microscopy (SEM) and X-ray photoelectron spectrometry (XPS), it was found that the acid substances from dust and the dry deposition of harmful gas could destroy the calcareous cement. This, along with salt crystallization, has caused serious weathering of the rock surface. These research results provide an important reference for the protection of grottoes in southwest China.

Abstract:The importance of traditional timber building components is of great significance to the assessment of the overall structural status of timber buildings. In order to clarify the importance of traditional timber building components, we developed a modified evaluation procedure based on load. The load distribution matrix was reconstructed based on load conditions and load redistribution, and the calculation method for component importance was improved based on load-bearing components. We took the main hall of Baoguo Temple, a typical traditional timber building, as an example, for carrying out the numerical simulation analysis, evaluating component importance based on the generalized stiffness, and analyzing the influence of each modification on component importance and the resultant change rate of the modifications to component importance. The results show that:the modified variation of the column class was -0.53% to 2.19%; that of the Liangfu class was -2.6% to 50.6%; that of the Puzuo class was -12.8% to 9.99%; that of the Tuan class was -7.6% to 6.9%. The component importance of the main hall of Baoguo Temple was:the column class>Tuan class>Liangfu class>Puzuo class. The modified importance of the column class and Liangfu class increased, but that of the Puzuo class and Tuan class decreased. This study could provide a reference for the structural state assessment and preventive conservation of traditional timber buildings.

Abstract:The atmospheric particulate matter is a kind atmospheric pollutant that threatens heritage sites and cultural relics. The deposition or adsorption of the particulate matter can cover the surface details of cultural relics, reducing the aesthetic value and causing further physical or chemical damages. With the goal of obtaining the chemical composition of the atmospheric particulate matter in a cultural heritage preservation environment, the mass concentration and chemical composition of TSP, PM₁₀ and PM2.5 in open caves (Cave 16 and Cave 257), a non-open cave (Cave 320) and outside were analyzed. In each observation season, the mass concentration of TSP ranged from 48.4 μg/m³ to 60.0 μg/m³, that of PM₁₀ ranged from 13.3 μg/m³ to 61.3 μg/m³, and that of PM2.5 ranged from 9.9 μg/m³ to 59.2 μg/m³. Whether or not the cave was open to the public had no significant effect on the concentration level and composition of the particulate matter in the cave, and the average I/O ratio of particulate mass concentration was mostly less than 1 in all caves, indicating that the particulate matter in caves mainly came from outdoor infiltration. Crust-derived mineral dust dominated the chemical composition of particles in all caves, accounting from 53.0% to 80.7% in spring and between 17.1% and 44.0% in winter. For other chemical components, the proportion of carbon and total water-soluble inorganic ions in fine particles was significantly higher than that in coarse ones. In winter, although the mass concentration of PM2.5 inside caves was relatively lower, the concentration and proportion of carbon and inorganic ions were higher than those in spring. The content percentage of carbon components and water-soluble inorganic ions was up to 60%. For the pollution control of the atmospheric particulate matter in Mogao Grottoes, attention should be paid to the hazards of fine particles and their chemical compositions.

Abstract:Bird excrement is one of the main factors causing the pollution of wall paintings and painted sculptures in grotto temples. Scientific analysis of the characteristics of damage of bird excrement to wall paintings is the premise of effective removal of such pollutants. In this study, Fourier transform infrared spectrometry (FTIR), gas chromatography-mass spectrometry (GC-MS) and X-ray diffraction (XRD) were used to analyze the composition of the Columba rupestris excrement on the surface of the wall paintings at Binglingsi Grottoes. Scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), electronic digital microscopy and polarized light microscopy (PLM) were used to characterize the microscopic damage characteristics of bird excrement on the simulated wall paintings. The results show that the excrement of Columba rupestris was mainly composed of uric acid, cellulose, polypeptide organic matter, and inorganic salts (mainly quartz). The excrement caused the cover pollution of wall paintings, erosion of the pigment layer and ground layer, and destruction of the original adhesion structure between pigment particles, resulting in the peeling and shedding of the pigment layer, soluble salt activity and other biological erosion. The research results have guiding significance for the scientific protection and restoration of ancient wall paintings.

Abstract:In recent years, it has been popularized in the market to use humidity-controlling building materials for building storehouses in order to regulate the storeroom humidity and reduce the energy consumption of air conditioning. To verify the application effect of humidity-controlling building materials—further reducing the fluctuation of temperature and humidity in the storeroom and save energy consumption—on the humidity control of museum storerooms, humidity-controlling building materials and ordinary building materials were used in our study to build storerooms. By setting different starting modes of the air conditioning system, the humidity of each type of storeroom at different stages was obtained and compared. The results show that the storeroom built with humidity-controlling building materials 1) had more uniform humidity inside, with the change being gentler and the correlation to the central position reaching 0.8 and 2) had a daily fluctuation lower than 2%. Therefore, the storeroom built with humidity-controlling building materials had a better control effect, and was able to save energy to a certain extent in combination with proper opening of air conditioning. This study provides some reference for the construction of cultural relic storerooms and the opening of air conditioning in storerooms.

Abstract:With the goal of solving the problem that the current environmental monitoring method cannot fully perceive the distribution of temperature and humidity in museum building spaces, this study introduces the computational fluid dynamics (CFD) simulation method, which can be combined with the data assimilation (EnKF) algorithm. Taking the exhibition hall space of a museum as an example, we obtained the visual simulation results of temperature and humidity fields and carried out the data analysis and related discussion according to the requirements of collection conservation. Compared with the real monitoring data, the CFD simulation based on data assimilation had good accuracy and the error was within an acceptable range. The technological method introduced in this study has realized the transformation from “point monitoring” to “field monitoring” for museum environmental monitoring. This could provide a more scientific and effective technological support for the preventive conservation of museum collections.

Abstract:The Statue of Eleven-faced Avalokitesvara in Guanyin Pavilion of Dule Temple has been preserved to the present day, but there are some diseases such as cracking, hollowing and falling off. The materials for the statue core were investigated using ultra depth-of-field 3D microscopy, X-ray diffraction and laser particle size distribution analysis. The contractility of clay samples was analyzed by controlling the contents of sand and fiber, and the effect of fiber content on the contractility of clay was explored. The results show that the raw materials for the statue core were taken from the local area, and the size of clay particles was mostly between 5 μm and 70 μm (accounting for about 79.5% of the total). The main mineral components were quartz and illite, with some albite and potassium feldspar and a small amount of kaolinite existing. For the coarse mud layer, the sand content was about 35%, the wheatgrass (a mixture of wheat straw and husk) content was about 6%-9%, and the length was mostly below 2 cm. For the fine mud layer, the sand content was about 30%, the hemp content was about 2.1%, and the length was mostly concentrated at 2 cm. The addition of wheat straw and hemp could inhibit the contraction of mud. With the increase of wheat grass content, the inhibitory effect increased first and then decreased, with the addition of 6% wheat grass boasting the best inhibitory effect. The final shrinkage rate of the sample could be significantly reduced by adding hemp, but the amount of hemp had little effect on the reduction rate. The fiber ratio of the statue core had a good effect of inhibiting contraction. In this study, material composition information of the core of the Eleven-faced Avalokitesvara statue was obtained, and as was the influence of fiber ratio on the contraction of the statue core. This work provides a reference for the restoration and conservation of the statue.

Abstract:This article provides a relatively comprehensive and detailed explanation of the conservation and restoration process of the main cultural relics, such as hemp pants and hemp coats, unearthed at Tomb M2009 of the cemetery of Guo State in Sanmenxia, Henan. Based on the preservation status and disease analysis, a physical method-based conservation and restoration plan was developed, and a series of reasonable restoration procedures and operating methods including clearing, disinfection and targeted cleaning, leveling and trimming, shape restoration, packaging and storage, were implemented to ensure good conservation of this batch of hemp fabrics and thus provide a guarantee for further research in the future. Additionally, we summarize some experience and options considered during this restoration process. These include controlling the cleaning intensity of hemp fabrics with loose structures, key points in leveling and shaping, and re-understanding the shape determination of cultural relics. This work provides first-hand information for further possible conservation and restoration, and also a valuable reference for the research, conservation and restoration of hemp cultural relics.

Abstract:The restoration of transparent jewelry relics is one of the difficulties encountered in the restoration and conservation of cultural relics. Because of the high transparency of such cultural relics, higher requirements are needed for restoration, transparency and permeability of restoration materials. Current research on the restoration of transparent jewelry relics is relatively not enough, and the restoration is often just simple splicing—because of a lack of practical high-precision restoration methods and corresponding restoration materials. To meet this need, a scientific simulation trial was carried out with a variety of restoration materials. After several tests and evaluation of the restoration materials from the perspectives of joint tightness, transparency and permeability, etc., it was found that the effect of Hxtal NYL-1 was the most reasonable. Then, by comparing and studying the current high-precision restoration methods for damaged cultural relics, in combination with the characteristics of transparent jewelry relics, a set of restoration methods for transparent jewelry relics using a vacuum process was designed. This method was able to strengthen the permeability of the restoration materials, solve the positioning problems in bonding and patching, and further eliminate the repair traces through the polishing with abrasive paste. Finally, this restoration method and corresponding restoration materials were successfully applied to the restoration of a crystal and beryl bead set unearthed from a Han Dynasty tomb in Hepu. The expected restoration effect was achieved, which further verified the feasibility and scientific soundness of the restoration method and materials for transparent jewelry relics.

Abstract:The selection of restoration papers is an important step in the restoration of ancient books, but their dimensional instability has not attracted enough attention. Restoration papers for ancient books are traditionally hand-made and have low strength after being soaked in water. The use of the current national standard testing method for dimensional instability of papers may cause the ripping and deformation of restoration papers. Therefore, a method to test the dimensional instability of restoration papers, namely the spraying method, was proposed. The relative moisture contents of restoration papers were measured using a moisture detector, in order to verify the feasibility of this spraying method from the perspectives of measurement time and operability. Moreover, the results of the spraying treatment and the soaking treatment achieved good consistency through analysis of the wetting-drying dimensional instability of more than ten kinds of commonly used restoration papers. We also discuss the applicability of dimensional instability testing to ancient books, and suggested the analysis of the dimensional instability matching degree between ancient book paper and restoration papers before restoration according to some specific cases. Since the spraying method effectively avoids the tensile deformation or fracture of restoration papers seen with the soaking method, the spraying method is suitable for the non-destructive testing of both restoration papers and ancient book paper. Thus, this method provides a scientific basis and a reference for the formulation of restoration strategies for ancient books.

Abstract:Chromatography and mass spectrometry are commonly used analytical methods for organic matters, and their applications in cultural relic conservation and archaeological residue research have been developed for decades. When chromatography and mass spectrometry are combined to analyze samples, it may be necessary to perform hydrolytic extraction, derivatization and other pre-treatments of the samples, which is cumbersome and time-consuming, and some samples may be lost during sample processing. Therefore, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) is now generally used to analyze organic materials. Py-GC/MS boasts the following advantages:1) no pre-treatments of samples—samples can be directly analyzed by thermal cracking, and the operation is relatively simple; 2) high sensitivity—identification of organic samples with multiple components can be realized; 3) small amounts of samples needed, which meets the detection requirements for the micro-destructive analysis of cultural relic samples. Therefore, Py-GC/MS plays an important role in the conservation and restoration of cultural relics and the identification of archaeological residues.

Abstract:i>Tangyang, paper models made to showcase the construction plan are precious cultural relics for the research on the Qing Dynasty imperial architecture. To contribute to the implementation of the digitalization of cultural relic information, the project team conducted an in-depth study of the collection and processing methods for the paper model data. After comprehensively considering the characteristics of various data acquisition methods and the difficulties of digital recording of paper models, the project team finally decided to use the combination way of a handheld 3D scanner and the multi-view 3D reconstruction technology to collect the basic data of the paper models, and then summarized a complete set of data acquisition and processing workflow through practice. In addition, the project team also made some attempts in terms of possible application methods of the results and formulated a construction scheme for the data management system to facilitate the later maintenance and further use of the data.