Abstract:The study and conservation of painted cultural relics are a focus of archaeology. However, it is difficult to preserve polychromic materials because of their fragility, so the restoration and reinforcement of painted cultural relics are necessary. Since most existing reinforcement materials are different from the cultural relics themselves, new “interfaces” will be formed after reinforcement. This will lead to cracking or even stripping of conservation materials from the body. This manifests itself at the macro level as “protective destruction”. In this work, we turned our attention to the use of animal gelatin, a traditional cementing material used for painted cultural relics. However, due to the sol-gel property of gelatin, it is difficult to use it directly on cultural relics. Therefore, a new idea—the use of micron-and nanometer-sized gelatins—was proposed for the first time. These species can effectively avoid the sol-gel property of gelatin, and effectively realize the conservation and restoration of raw materials by means of “penetration first, then cross-linking”. Gelatin microspheres (GM) with the sizes of 2~4 μm were prepared by emulsification-coacervation under mild conditions and were then evaluated using SEM and FTIR. Comparison with the raw gelatin showed that it was micron-sized gelatin. The gelatin microspheres were applied to painted sample blocks simulating cultural relics for permeability and breathability experiments. Preliminary experiments showed that the depth of penetration of the GM could meet the requirements for reinforcement of painted cultural relics. The experimental sample blocks reinforced with GM have good breathability and meet standards required of conservation materials. In the future, after more experimental testing, gelatin microspheres are expected to be put into use.

Abstract:This study discusses the multi-cycle method for reinforcing ancient bone materials by soaking in sources of calcium ions and phosphate ions and collagen mineralizing solution-gas diffusion, and investigated the conservation effect using ultra-depth of field microscopy, Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD),scanning electron microscopy (SEM), color analysis and compressive strength testing. The results show that, for the biological apatite bone treated by this method, the reinforcement material has the same composition as that of the bone itself and features in-situ synthesis and deep penetration into the bone, overcoming some disadvantages of simple physical filling with organic polymers and other mineral materials. The method boasts a simple treatment process, high efficiency and small changes in appearance, thus meeting the requirements for the reinforcement of fragile bone cultural relics as well as human and animal bones.

Abstract:Pores are not only a part of the fiber skeleton, but also an important channel for external substances to enter and exit. At present, there are few studies of the nanoporous structure of ancient silk fabrics, and the pore size is the only evaluation index, showing the lack of various evaluation indexes. In this study, the degradation characteristics of ancient silk fabrics were studied using infrared spectrometry and electron paramagnetic resonance (EPR) spectrometry. The low-temperature nitrogen adsorption method was used for the characterization of the pore structure within silk fibers, and the microscopic pore structure was studied with regard to pore shape, pore size distribution, specific surface area, pore volume, average pore size and fractal dimension. The results show that compared with modern silk fabrics, deterioration of the Huangshan sample (Qing Dynasty), the Nanling sample (Northern Song Dynasty) and the Chenzhou sample (Warring States Period) is more and more serious in sequence. Analysis of the pore structure shows that there are both cylindrical pores and slit pores in all the samples with a wide range of pore size distribution, indicating that the pore distribution is continuous and there are complex multistage structures in the silk fiber. Among these, the adsorption capacities of the Northern Song and Warring States samples are much higher than those of the modern and Qing Dynasty samples, suggesting that there are more macropores or open pores in them. The results of the Barrett-Joyner-Halenda (BJH) and nonlocal density functional theory (NLDFT) methods show that pores of the samples are mainly mesoporous, with the pore size mainly distributed below 20 nm and the inherent aperture inside the silk fiber being about 2.8 nm. The data of specific surface area and pore volume show that the Huangshan sample with less deterioration has a higher specific surface area and the increase of its pore volume mainly comes from small pores, while the increases of pore volume of the Nanling and Chenzhou samples mainly come from large pores. In addition, the data of fractal dimension show that there are at least three kinds of self-similar pore structures in the samples and the order of pore complexity from high to low is the Huangshan, modern, Chenzhou and Nanling samples. According to the nitrogen adsorption method-based research, nanoporosity evaluation indexes of silk have preliminarily been established, which provides a new perspective for the theoretical research on the pore structure of ancient silk fabrics and the formulation of conservation strategies.

Abstract:The salt damage is a common problem at earthen sites. There are serious phenomena of the salt damage on the surface of Jinsha earthen site. Research on the distribution and evolution of the salt damage is the first step toward a science-based strategy to protect Jinsha earthen site, and also a prerequisite for further exploring the pathogenic mechanisms of the salt damage. In this study, we collected the existing investigation data of Jinsha earthen site from 2010 to 2020 and conducted qualitative and quantitative analyses of the type, distribution characteristics and evolution process of the salt damage at the site using the on-site investigation and image processing technology. The results show that the main types of the salt damage at Jinsha earthen site include salt efflorescence, crisp powdering, hollowing, peeling and erosion. The main distribution areas are near the northwest corridor and ancient river channels, and the sidewalls of machine-dug pits present the most serious damages. From top to bottom, the salt damage transition from salt efflorescence to single crisp powdering, then hollowing and peeling and finally erosion at the bottom layer. In later stages of all types of the salt damage, distribution ranges become larger, development rates become faster and damage degrees of earthen sites become greater. Distributions of soluble salt contents along the height are not only related to the capillary rise, but also related to the development process of the salt damage.

Abstract:The physical, hydraulic and mechanical properties of site soil, as well as the environmental differences found there, have impacts on the conservation of earthen construction sites as a whole. The stability of remixed soil properties of remolded samples is the basis and prerequisite for scientific evaluation and comparative analysis of experimental studies, since using remolded samples instead of earthen sites are an important means for testing various properties. In this study, based on different methods of soil mixing, we comprehensively evaluated the influencing conditions of different soil mixing methods by observing, photographing, measuring the sizes of soil aggregates and testing the unconfined compressive strengths of samples prepared under the same conditions. According to the results, the most stable soil samples were those which had been smothered for 24 hours, and the strengths of the soil samples gradually decreased with the increase of the smothering time again. This study provides theoretical and technological support for the indoor experimental research on soil mixing of earthen construction sites.

Abstract:Lead-barium glass is a unique kind of glass from ancient China, dating from the Warring States Period to the Han Dynasties. As more and more intact lead-barium glass objects have been found, study of glass corrosion and conservation issues has been carried out. Chemical compositions and microstructures of two Qin Dynasty lead-barium glass samples excavated from Shaanxi and Henan Provinces were determined using scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX), optical microscopy (OM) and laser Raman spectrometry (LRS). Based on the results, the main corrosion product of lead-barium glass is PbCO₃ and most of barium salts have been lost to the environment or the surface of the corrosion layer. Formation of the corrosion layer structure is related to periodic changes of environmental water levels and pH values. This study could provide some valuable information both for lead-barium glass conservation and its preventive conservation work.

Abstract:Copper coins produced by the Sichuan-Shaanxi Soviet government are important revolutionary relics, which deliver the glorious history of the Sichuan-Shaanxi Soviet Area during the Second Revolutionary Civil War. In order to preserve them for their part in history, the components of these copper coins (two face values, three patterns and nine versions) were determined using energy dispersive X-ray spectrometry (EDS) and their places of production and sequence were then investigated. It was found that the content of copper in these coins was much higher than that in brass coins produced in the late Qing Dynasty and the Republic of China. With the development of history, their content of copper gradually increased to 95% or so, and their contents of zinc, lead and tin correspondingly decreased. Big 200-wen copper coins produced in the early period and some small 200-wen copper coins with a smooth margin produced in the middle and late periods were manufactured through the fusion of red copper coins and other copperwares. Small 200-wen copper coins with a dentate margin and 500-wen copper coins with a simplified Chinese character of “Lian” produced during the golden age can be classified as red copper coins. This dynamic evolution of copper coins suggests that the coin-producing institution of the Soviet government screened raw materials more and more strictly, reflecting the rational management and utilization of copper resources by the Soviet government.

Abstract:In our study, in order to understand the alloy compositions and microstructural characteristics of different types of bronze drums, scanning electron microscopy and metallographic microscopy were used to inspect and analyze fifteen bronze drums in the collection of the Anthropology Museum of Guangxi. Our results and previous research results of the alloy proportions and casting process characteristics of various types of bronze drums are further discussed here. The alloy composition results show that 1) the Shizhaishan-type bronze drum was made from Cu-Sn alloy, with a high tin and lead-free alloy ratio; 2) the Beiliu-type, Lengshuichong-type and Lingshan-type bronze drums were made from Cu-Sn-Pb alloys with relatively higher contents of lead and tin, and they have the characteristics of stable alloy ratios, use of stamping patterns, and small fluctuations of the height-diameter ratio; 3) the Majiang-type bronze drum has a high tin content and a large fluctuation in lead content. The microstructural observation shows that one Shizhaishan-type drum has slip bands and recrystallized structures, two Majiang-type drums have local slip bands, and the other drums are all as-cast structures, with the intergranular distribution of the (α+δ) eutectoid in the α solid solution, all having sulfide inclusions, and most of them have dispersed or aggregated distributions of lead particles of varying amounts, and high-iron phases, cuprous oxide and copper particles can be seen in some samples. Seven Majiang-type drums present more microscopic shrinkage holes located in the middle of the sections. The alloy ratios, inclusions and casting defects of different types of bronze drums reflected in the analysis results of this study could provide basic information for the research on bronze drum casting techniques.

Abstract:The Spring and Autumn bronze Ding with intertwined hydra patterns from the tomb of Prince Zheng in Shenzhen Museum had been restored before entering the museum, but the record of restoration is missing. The aging of the original protective and repair materials due to the long time and the influence of the preservation environment has caused the left and right legs to break and drop off from the original welding places. There are also many cracks and other diseases. Therefore, the Ding needs urgent conservation and repair again in order to restore its integrity and stability and to enhance the display effect. In this study, the material compositions, manufacturing techniques, early repair materials, treatment methods and diseases of the Ding were analyzed using X-ray detection, XRF, FTIR and XRD, etc. The results show that the Ding is made of a ternary alloy of copper, tin and lead, the body is covered with repair, welding and distressing marks, and there are many cracks. Brass sheets were used for patching (the white patching material is a powdered mixture of gypsum and potassium alum). A lead-tin material was used for welding. No chlorine element was found. The study results provide a sufficient basis for further understanding the value of the Ding, scientifically assessing its preservation status and degree of disease, and carrying out scientific and effective re-conservation and restoration.

Abstract:Silver, as a kind of important decorative material, has widely been used in various silver-decorated lacquerwares, but the color of its decoration parts has often become blue-gray. This study focused on the analyses of a Ming Dynasty black lacquer cabinet with colored and gold-painted design and two other cultural relics collected in the Palace Museum, using scanning electron microscopy-energy dispersive spectrometry, X-ray diffraction and other methods. Meanwhile, the mechanism of generation of the blue-gray part was explored. The experimental results show that the main elements of the blue-gray layer on the surfaces are silver, sulfur and chlorine and the main phase is acanthite (Ag₂S) or a mixture of acanthite and chlorargyrite (AgCl). The structure of the blue-gray silver strip on the black lacquer cabinet is complicated due to natural corrosion as well as artificial coatings, the making technique of which may be similar to the “niello” technique in Western countries. This study provides an important theoretical basis for the conservation and restoration of silver-decorated lacquerwares.

Abstract:Restoration of mortar is an important part of the restoration of lacquerware relics. In order to disclose the materials of three typical mortars used for lacquerwares collected in the Palace Museum, X-ray fluorescence spectrometry, micro-X-ray diffraction, Fourier transform infrared spectrometry, fiber microscopy and pyrolysis-gas chromatography/mass spectrometry were applied to identify the inorganic and organic components contained in the lacquerware mortars. The research results suggest that 1) mortar of the plum blossom and banana leaf-styled Guqin of the Ming Dynasty is composed of animal horn or bone ashes, Chinese lacquer and a small amount of vegetable oil; 2) mortar of the black lacquer throne with gold decoration of the Qing Dynasty is composed of clay containing calcite, boiled tung oil and porcine blood; in addition, the sample also contains hemp fiber, which should be the linen mounted between the wooden body and the mortar layer of the throne (mortar of the throne not only provides a flat surface for lacquering, but also solidifies the linen); 3) mortar of the black lacquer couplets with filled gold characters written by Zhang Tingyu of the Qing Dynasty is composed of clay, boiled tung oil and porcine blood. The analytical methods applied in the present study permits rapid and accurate identification of the materials of mortars used for lacquerwares, especially the organic binding materials. Material selection of the three typical mortars is consistent with the traditional manufacturing methods for lacquerwares, especially furniture and objects of the Ming and Qing Dynasties. These research results could be directly applied to the restoration of lacquerwares.

Abstract:The green lotus-shaped lacquer bowl unearthed from a Song Dynasty tomb at Bashi Town of Wuxi is a very rare “dark-green lacquer” object. The green lacquer specimen was analyzed and studied using 3D video microscopy, laser micro-Raman spectrometry (LRS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The results show that 1) the green lotus-shaped lacquer bowl was made through the processes of body making, plastering and priming, and red and green finish lacquering; 2) the material for the body is Chinese fir (Cunninghamia lanceolata); 3) vegetable oil and Chinese lacquer were used as the binding materials for the plaster while cooked tung oil was added as an auxiliary in Chinese lacquer for the finish. In addition, it is worth noting that cinnabar colors the red lacquer film and a mixture of gamboge and indigo pigments the green one. This study is the first scientific attempt of its kind to identify the production techniques for “dark green lacquer” objects.

Abstract:Temperature and humidity are important factors for evaluating the preservation microenvironment of cultural relics. At present, a large number of monitoring data for the preservation microenvironment of cultural relics have been generated, based on the requirements for the preventive conservation of cultural relics. It is an important subject in the preventive conservation field to better analyze and utilize existing data and to establish an effective mathematical analysis model for evaluating and optimizing existing environmental control measures. In this study, we used computational fluid dynamics (CFD) methods to establish a three-dimensional CFD simulation model that can predict the transient changes of temperatures in a showcase according to the surrounding environmental temperature changes. Through the transient temperature boundary modeling method, the measured environmental temperature data outside the showcase were interpreted using UDF (user defined function) as the transient boundary condition of the model. The model was calibrated using the measured temperature data in the showcase under summer conditions, and the calibrated model was directly applied to winter conditions. The results show that the calibrated model worked well in summer conditions. The average deviation between the simulated value and the measured value was 0.18 ℃, and the maximum deviation was 0.33 ℃. The model was directly applied to winter conditions and showed a good predictive effect. The average deviation between the simulated value and the measured value was 0.029 ℃, and the maximum deviation was 0.081 ℃, which further verified the effectiveness of the model. This study provides a new idea for the utilization of monitoring data for preventive conservation and their quantitative research, and, at the same time, demonstrates broad prospects for the application of CFD technology in the field of cultural relic conservation.

Abstract:Samples of dustfall collected from the surfaces of wall paintings and painted sculptures in Mogao Grottoes, were analyzed as to physical and chemical properties, such as particle size distribution, chemical composition, microscopic morphology and soluble salt content. In addition, the influences of dustfall on wall paintings and painted sculptures in Mogao Grottoes were further studied. The results of the study show that 1) most of the dustfall deposited on the surfaces of wall paintings and painted sculptures in Mogao Grottoes is the crustal source mineral; 2) the potential harms to wall paintings and painted sculptures in the grottoes are physical covering and abrasion and 3) over long periods of time, dustfall will bring potential chemical threats, such as salt erosion, to wall paintings and painted sculptures. Dustfall on the surfaces of wall paintings and painted sculptures in Mogao Grottoes is an important factor that cannot be ignored as a cause of disease of wall paintings and painted sculptures. The results of the study provide basic data for the preventive conservation of wall paintings and painted sculptures in Mogao Grottoes.

Abstract:Considering the data transmission problems and developmental trends for the conservation and utilization of Mogao Grottoes, it was proposed to use wireless network deep coverage technology to build a data transmission platform to solve the problem that conservation and utilization data could not be transmitted in large caves of Mogao Grottoes. In order to build a robust transmission platform, we took the following measures:first, depending on the characteristics of the various operational data collection methods, transmission modes and transmission mechanisms, etc. for the conservation and utilization of Mogao Grottoes, we proposed requirements for building a data transmission trial platform based on wireless network deep coverage technology; second, we designed a trial platform, with its location being determined in accordance with the distribution and architectural shape of Mogao Grottoes, and in combination with the current situation of wireless network coverage in Mogao Grottoes, the key technology of wireless network deep coverage was determined through model selection analysis, and the technology was applied to build a trial platform; finally, the wireless signal coverage, signal strength, transmission performance and security of the trial platform were verified to ensure the integrity and continuity of data transmission. This trial platform has been running for more than one year with good results.

Abstract:Beeswax is one of the most common materials which can be easily acquired from nature, and occupies an important position in the ancient human societies. Analysis of beeswax residues can directly provide scientific evidence of the utilization of beeswax. This paper introduces the production and composition of beeswax, reviews the analytical methods for beeswax residues, and summarizes the scientific identification evidence of beeswax residues, all of which could throw light on the utilization of ancient beeswax and other related issues for further research.