Abstract:Brass coins were used in ancient China from the mid-Ming Dynasty to the late Qing Dynasty. In the past, scientific research on ancient coins mainly focused on alloy compositions and casting techniques, but the main research object of corrosion products and mechanisms was bronze. Brass contains more zinc than does bronze, so the corrosion products and behavior of brass are different from and more complicated than those of bronze. However, there is a lack of research on this aspect in the existing literature, and the research on corrosion products and behaviors of brass in the atmospheric environment is less. In this study, three analytical techniques, such as X-ray fluorescence (XRF) spectroscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and Raman spectrometry were used to detect alloy compositions and corrosion products with different colors of some Ming and Qing brass coins collected in the National Museum of China. The results show that 1) the brass coins of the Jiajing, Longqing and Wanli periods of the Ming Dynasty are Cu+Sn+Pb+Zn alloys with average contents of 66.4% Cu, 6.8% Sn, 10.4% Pb and 15.6% Zn, with traces of Fe but no As and 2) the brass coins of the Taichang, Tianqi and Chongzhen periods of the Ming Dynasty and various periods of the Qing Dynasty are mainly Cu+Pb+Zn alloys with trace amounts of Fe, As and Sn. The brass corrosion products are different from the bronze patinas, and many of them are newly found or rare. The typical corrosion products are blue-green and white. Based on the analyses and related literature, it is preliminarily confirmed that the blue-green one is an organic acid salt containing copper and sodium ions, with its empirical chemical formula being NaCu(CO₃)(CH₃CO₂). Three Raman spectra of white corrosion products were collected, but no standard Raman spectrum could be matched with them. In combination with various analytical results and the preservation environment, it can be further inferred that the white ones with three different phases are mainly carbonate or organic acid salts containing Zn and Cu cations and that Zn is the dominant element. In addition, two rare isomers, herbertsmithite and kapellasite, both having the stoichiometric formula, Cu₃Zn(OH)₆Cl₂, were identified using Raman spectroscopy. In addition, the formation of the corrosion products is also discussed in this paper. In combination with the storage environment, it is deduced that the acetate in the blue-green corrosion product could come from the organic acid volatilized from wooden cabinets, and the sodium and carbonate may be due to the contamination before storage. This paper has two main aspects:the first is to take brass as the research object and to identify several newly found or unusual corrosion products using Raman spectroscopy, which could further supplement and improve the database of brass rust species; the second is to deeply investigate the impact of wood volatiles on the corrosion of metal collections, which could provide a reference for the subsequent adoption of targeted preventive conservation measures and related research.

Abstract:Located in the northernmost part of Xinjiang, Altay Prefecture boasts rich cultural exchanges with the Eurasian Steppes. Since the development of metallurgical technology is closely related to the beginning of human civilization, we selected nine artifacts—bronze Fu (cauldrons) and harnesses—representing nomadic cultures as research objects, in order to explore the metallurgical development of Altay Prefecture. The metallographic structure and composition of 16 samples were analyzed using metallographic microscopy, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). Technical characteristics of their production are discussed in the paper. It was found that the casting process was generally adopted for the early Iron Age bronzes in Altay Prefecture, and their components are mainly pure copper, arsenic-copper and lead-arsenic-bronze. The results provide an important reference for the research on the metallurgical development in Altay Prefecture, Xinjiang.

Abstract:In order to provide a scientific basis for the conservation and restoration of the bronze beast-face decorations unearthed in Chenggu County, Shaanxi Province, and to further reveal the production techniques and related archaeological information, five bronze beast-face decorations were analyzed, non-destructively, using X-ray inspection, hyper-depth-of-field microscopy, X-ray fluorescence (XRF) spectrometry and Raman spectrometry. The results show that two of them are tin bronze and the other three are lead-tin bronze. The corrosion objects on the surface of them are dominated by CuCO₃·Cu(OH)₂, Fe₂O₃, lepidocrocite γ-FeOOH and CaCO₃ in some areas. In addition, their processes of casting, traces of re-casting, proportion of copper materials and the process of production of small holes are discussed. These bronze beast-face decorations are also compared with the same types of artifacts unearthed at Yin Ruins and Laoniupo. It is concluded that the craftsmanship and style of these bronze beast-face decorations are consistent with those of other bronzes in this area. This information provides a data basis for understanding the “Chengyang Bronze Group” from the perspective of materials and craftsmanship.

Abstract:The No.1 bronze sacred tree discovered at the No.2 pit of Sanxingdui site is large in size and complex in structure. Due to its various diseases, such as corrosion and cracks, the structural stability of the tree has always been the focus during its exhibition. In order to fully record and evaluate the preservation conditions of the tree and understand the stresses placed upon it, our study, based on the original geometric form and internal structure, applied the 3D digital modeling technology to establish geometric and numerical models of the bronze tree. This technology also helped to estimate some immeasurable data, such as the mass distribution and position of the mass center of the tree. In addition, the safety of the still bronze tree was analyzed in terms of stress and displacement using the finite element method. According to the results of the finite element method and simplified calculation of mechanics of materials, the connecting joints between the dragon body and the trunk, and the ends of branches are under high stress and vulnerable to damages. This study could provide scientific references for the installment of consolidation joints and other measures for the display of the No.1 bronze sacred tree.

Abstract:During renovation of the Hall of Mental Cultivation (Yang Xin Dian), the treasure box located in the center of the ridge showed the culture of treasures in imperial buildings of the Ming and Qing Dynasties. Treasure boxes are an essential part of buildings in the palace. Often placed in the boxes were many kinds of items for suppressing evil, among which organic items have varied greatly. In the treasure box of the Hall of Mental Cultivation, there are coins, ingots, precious stones, silk fabrics and several wooden strips. The wood strips have aged and turned black and are difficult to identify. In our study, the species of wood were identified using traditional microscopic structure observation. According to the preliminary judgment, the strips are made of five types of wood:Aquilaria sinensis (Lour.) Spreng., Santalum album L., Dalbergia cochinchinensis Pierre., Dalbergia latifolia Roxb. and Pterocarpus macrocarpus Kurz.. The first two belong to fragrant herbs and the last three belong to rosewood. The discovery of the three kinds of rosewood also provides direct evidence for their use in the court of the Jiaqing period. In the light of literature research, the utilization of resources within the Qing court, the corruption of officialdom and other factors resulted in the replacement of some incense and herbs, grains with wood pin strips by officials in charge of restoration. The identification of wood strips in the treasure box of the Hall of Mental Cultivation is of great importance for understanding the culture of treasures and utilization of wood in the mid-Qing court as well as the social background of this period.

Abstract:Considering the deficiency of technologies used for the identification of species of plant fibers in ancient painted clay sculptures and murals, we developed a set of methods based on fiber cross-section cell morphologies and carried out a series of experiments of chemical degumming to extract single fibers, fiber cross-section slicing and fiber cross-sectional cell morphological comparisons. The methods were applied to nine kinds of plant fibers, including rice, wheat, corn and sorghum straws, various kinds of hemps and cotton, which are commonly seen in painted clay sculptures and murals. Fibers in the mud layers of painted clay sculpture samples from Sumeru Grottoes in Ningxia and Maijishan Grottoes in Gansu were tested and identified. The results show that 1) for painted clay sculptures at Sumeru Grottoes, wheat straw and jute fibers were added to the coarse mud layer, ramie fibers added to the fine mud layer and cotton fibers added to the fine part of sculpture fingers and 2) wheat straw fibers were added to the mud layer of painted clay sculptures at Maijishan Grottoes.

Abstract:Our study dealt with the material and technical aspects of newly discovered painted plaster fragments excavated from Xitou site in Xunyi County, Shaanxi Province (Xunyi is one of the earliest birthplaces of the Zhou Dynasties). A multi-technical approach was employed to identify the inorganic and organic materials in the painted plasters. The plaster layer and pigments were investigated by means of polarized light microscopy, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and Raman spectrometry. The results show that the pigments are iron-based ones (red and yellow ochre) and green earth. The plaster layer is mainly consisted of calcite, while a thin lime mortar forms the backing between the lime plaster coat and the painted layer in some samples. The adhesive ingredients were analyzed using gas chromatography-mass spectrometry (GC-MS). The results show that the binding materials on the painted plaster contain animal glue and perhaps egg. In addition, through comparison, it was found that the technique used for the painted plasters in Xunyi was similar to that used for other typical Chinese archaic murals. This study could help us explore the origin and history of murals in Guanzhong area during the pre-Zhou period.

Abstract:Attapulgite clay is well-known as a “universal soil” and has been widely used in industrial production. In our study, it was compounded with magnesium hydroxide—an alkaline medium commonly used for deacidification of paper—to produce a new composite material. After several trials, it was determined that the magnesium hydroxide loading in this composite was at most 25%. The dispersion of the composite was confirmed using transmission electron microscopy (TEM). Physical property analysis showed that attapulgite clay was a good carrier for the deacidification material, and verified the formation of the composite. Subsequently, this composite material was applied to paper deacidification. Through comparison, it was found that the deacidification performance of the composite was superior and that the properties of the paper were significantly enhanced after deacidification.

Abstract:In order to improve the mechanical properties of hydraulic lime and to appropriately increase its compressive and flexural strength, we designed and prepared hydraulic lime with different proportions of polypropylene fiber, metakaolin and fine sand, and experimentally studied the mechanical strength, mineral composition and morphology of each mixture. The results show that the compressive strengths of hydraulic lime mixtures containing 30% metakaolin, 0.1% polypropylene fiber or 50% quartz sand only are relatively higher. Metakaolin-hydraulic lime presents improved long-term compressive strength when 0.1% short-length polypropylene fiber is added alone or 0.1% polypropylene fiber and 50% quartz sand are added together. The flexural strength of hydraulic lime containing polypropylene fiber is also increased. The decrease of long-term compressive strength is related to the instability of calcium-aluminum hydrate, and the carbonation reaction can be increased by adding 1% polypropylene fiber. The friction and anchoring forces can also be increased by adding polypropylene fiber. Modified hydraulic lime was used in the conservation of architectural murals of the Taiping Heavenly Kingdom at Luolang Lane in Nanjing. Its application to the local restoration of ground layers achieved good effects.

Abstract:In 2018, a bronze belt hook of the Warring States Period, inlaid with gold and turquoise, was unearthed from Tomb No.1 (M1) of Xigang Cemetery at the capital city site of Zhu State, Zoucheng City, Shandong Province. The belt hook was seriously corroded and in urgent need of conservation. Some information about the quality of the materials of the belt hook was acquired by means of X-Ray inspection, X-Ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectrometry (SEM-EDS). In order to determine its artistic and scientific value, conservation work was carried out. In the process of conservation, it is found that the cross-sectional morphology of a gold wire is an inverted triangle or inverted trapezoid, and that a wider gold wire is formed through the bending and winding of a single narrower gold wire. These unique technological features have never been reported in previously published materials. This provides new valuable information for the study of ancient gold and silver-inlaying technologies.

Abstract:The Han Dynasties were the heyday of lacquerware development. A large number of painted lacquerware objects have been excavated from Tushantun Han tombs in Qingdao, Shandong. Most of them have one to two thin layers of lacquer, but fragments of a lacquer Lian unearthed from Tomb M162 have five layers of lacquer. Furthermore, each lacquer layer is thicker than that of other lacquerware from the same period of the Han Dynasties. In this study, digital microscopy, X-ray photoelectron spectrometry (XPS), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy and energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and other methods were used to analyze the fragments of the lacquer Lian unearthed from Tomb M162. According to previous research results, the Lian is a Han Dynasty lacquerware specimen with the largest number of red lacquer layers found so far and its production process is more complex than that of single-layer lacquerware. The development of this multi-layer lacquering process with the same color may be regarded as the origin of the craft of carved lacquerware production.

Abstract:Based on long-term monitoring of the diseases of the earthen site, temperatures and humidity in the museum, water contents at different depths, and also on measurement of the permeability coefficients and hardness of soil samples, it is found that the repeated occurrence of flooding, spalling and serious mould in winter and spring is related to the periodic change of moisture in soil by the “unidirectional evaporation” in a relatively closed environment, and that the direct damage of piping in the earthen site is caused by the seepage due to lawn watering, rainfall and urban drainage into the site. The mechanism of soil damage caused by groundwater changes was analyzed and primary measures to prevent drastic groundwater changes of the earthen site were advanced. This study aims to provide a reference for the conservation of the earthen site of Xi’an Tang Hanguang Gate Museum.

Abstract:The odors of cultural heritage objects not only reflect their historical information, but also have lasting impacts on the objects themselves. Therefore, understanding the odors of cultural heritage objects is of great significance for research and contemporary conservation. In this work, solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) were used to collect, separate and analyze the odors emitted from the head margin paper of a scroll painting collected in the National Museum of China. The results show that the method could effectively collect markers related to paper degradation (such as fatty acids, aldehydes and ketones). In addition, the detection of other biomarkers (such as agarospirol) also reflects information about the historical preservation environments of the scroll. This method plays an important role in understanding the historical value and scientific conservation of the painting.

Abstract:In the practical application of current environmental monitoring systems for the preservation of cultural relics, there are various problems, such as complicated wiring, poor network communication stability, high installation and maintenance costs and frequent battery replacement, etc. This work made a comparative study of the application status and characteristics of several mature network communication technologies used in environmental monitoring systems for the preservation of cultural relics. The existing 433 MHz technology monitoring system of Sichuan Museum was taken as an example to comparatively analyze the advantages and disadvantages of using three types of network communication technologies (433 MHz, LoRa and NB-IoT) through experiments of application scenes in the museum, from the perspectives of signal strength, packet loss rate and battery power consumption. We found that the 433 MHz technology-based monitoring system had obvious disadvantages, including complicated site wiring, high construction costs, difficult installation and maintenance, etc. By comparison, the LoRa or NB-IoT technology-based monitoring system could greatly reduce installation and maintenance costs, while also decreasing the transmission loss of intermediate nodes. However, the signal quality of all test points did not reach the coverage effect required for monitoring. This problem needed be solved by adjusting the deployment of monitoring systems and optimizing the network application performance. Based on these considerations,as well as practical requirements for the preventive conservation of cultural relics, we propose a new environmental monitoring system, which is convenient and quick in layout installation and low-cost in use and maintenance. This research provides a considerable reference for the network structure selection of environmental monitoring systems for the preservation of cultural relics, and for the construction of preventive conservation projects in museums.

Abstract:Chinese shadow puppetry has been listed in the UNESCO’s Representative List of the Intangible Cultural Heritage of Humanity. One of important carriers of Chinese culture as they are, Chinese shadow puppets are now facing extinction. Heilongjiang Nationalities Museum, founded in 1985, has collected more than 2 000 high-quality shadow puppets, some of which are more than 100 years old. However, because some pieces of the shadow puppets are made of organic leather, their service life is limited, not conducive to preservation. In order to conserve the shadow puppets better, the authors conducted comprehensive conservation research on the collection of shadow puppets using the digital technology. With the cooperation of shadow puppetry inheritors, the authors improved the basic information about the shadow puppets, realized the digital collection of shadow puppets, and established and improved the shadow puppet relational database. This work has improved the conservation and inheritance levels of shadow puppets, accumulated the digital collection experience of shadow puppets, and could promote both the static and dynamic management of collection information.