Abstract:The destruction of cultural relics by mold has become a main factor in the biological degradation of cultural relics, and the prevention and control of mold has also been a major challenge in the field of cultural relic conservation for a long time. Microbial testing is an important part of biological management in the preventive conservation of cultural relics and the prevention and control of harmful organisms. Timely provision of hazard analysis information can effectively reduce the frequency of microbial pollution and the probability of disease risk occurrence. In this study, the adenosine triphosphate (ATP) bioluminescence method was used to detect the bioluminescence values of 50 kinds of molds isolated from the surface of cultural relics. The linear relationship between the total number of colonies obtained by plate counting and ATP bioluminescence value was constructed for seven common molds and their mixture. The difference between the predicted total number of colonies and the actual one under the corresponding linear relationship was analyzed. Also, the ATP bioluminescence method was used to evaluate the inhibition effect of citronellal fumigation on the surface of simulated mold-infected samples. The purpose of this study is to determine the scientific feasibility and applicability of the ATP bioluminescence method in the detection of mold pollution on the surface of cultural relics. The results show that the bioluminescence value (RLU) was detected in 90% of the 50 tested fungi; the maximum one (RLU_max) was 9999. Under different culture conditions, there was a good linear relationship between the logarithm of total colonies (lgCFU/mL) of Penicillium sp., Aspergillus sp., Trichoderma sp., Chaetomium sp., Cladosporium sp. and their mixed fungi and their corresponding logarithm of bioluminescence values (lgRLU); the correlation coefficient was R²>0.981 7. Under the corresponding linear relationship, the predicted total number of colonies has no significant difference with the actual plate count (P<0.05), indicating that the method could be accurately used for quantitative detection of mold on the surface of cultural relics. In addition, the bioluminescence data and the total number of colonies of mold on the surface of cultural relics in the citronellal fumigation group and control group showed the same change trend, indicating that the method could be directly used to evaluate the anti-fungal effect. Therefore, the ATP bioluminescence method has high applicability in the detection of molds on the surface of cultural relics. The ATP bioluminescence method has good application value in the analysis of the degree of moldiness of cultural relics and the evaluation of the effect of anti-fungal treatment on moldy cultural relics, and could provide effective technological support for the prevention and control of biological degradation of heritage collection.

Abstract:The Shui-Lu wall paintings, a kind of religion-themed wall painting in North China, at Gucheng Temple is located on the walls of an early 16th century building—Sakyamuni Hall—of the temple. The theme of the paintings integrates three religions—Confucianism, Taoism and Buddhism—making the paintings an important case for the study of the history of Chinese painting art and the development of local religions in North China. However, the period of the paintings still remains controversial. There are two hypotheses:one tells that the paintings were finished in the same year of Sakyamuni Hall in 1507 (the 2nd year of the Zhengde period of the Ming Dynasty), which is referred to in a few publications; the other believes they were painted between the 1820s and 1840s (the Daoguang period of the Qing Dynasty), particularly earlier than 1849 (the 29th year of the Daoguang period) according to the records of the donors and related genealogies and inscriptions. We studied the craft and materials of the Shui-Lu wall paintings at Gucheng Temple. The result also contributes to the periodization of the paintings together with historical records. Based on onsite investigations, material analysis of the paintings was carried out using section microscopy, Raman spectrometry (Raman), scanning electron microscopy with energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and infrared spectrometry (IR). As a result of the analysis, the structures and material compositions of the paintings were clarified. The structural layers of the paintings from inside to outside are core support, coarse plaster layer, fine plaster layer, white ground layer, paint layer and embossed painting and gilding craft. The difference is that the painting on the north wall consists of sketch layer, sticker layer (paper) and paint layer in turn outwards on the white ground layer. The coarse plaster is dominated by loess and wheat-straw, and the fine plaster is mainly composed of clay, pebble (0.5~2 mm) and animal fibers—usually, small pebbles are rarely seen in the fine plaster of painting. The pigments used on the paintings are mostly minerals. The red and orange ones are cinnabar, the pink one is mixed with red lead and cinnabar, the black one is carbon black, and the blue one is Prussian blue. The green pigment is botallackite, with a small amount of chalcocite, which was rarely found on wall paintings in China. The gold foil used in the embossed painting and gilding craft is Au-Ag-Pb alloy, with Au accounting for 75.19%, namely Dachijin. Using IR, the material of the sticker layer in the painting on the north wall was identified as paper, which was made with the addition of ceramic clay; the pigments used were consistent with those on other walls. The presence of the sticker layer beneath the paint layer of wall paintings is an extremely rare phenomenon, and few related reports are available. Considering that Prussian blue was introduced and exported into China during 1760s to 1770s (the mid and late Qianlong period of the Qing Dynasty), and Yuxian County, where Gucheng Temple is located, was a local commercial hub from mid-17th century, it is believed that the paintings were finished between 1760s and 1849 (from the mid and late Qianlong period to the 29th year of the Daoguang period). In this study, material analysis was innovatively applied to the periodization of wall paintings. It not only describes a scientific methodology to estimate the period of East-Asian wall paintings, but also contributes to the understanding of the Shui-Lu wall paintings of Gucheng Temple for its conservation and restoration. The outcomes of this study provide reference about local wall paintings’ craft and materials in Yuxian County, and also help to comprehend the social and technical development in pre-modern North China.

Abstract:Guanzhuang site is located in the west of Guanzhuang Village, Gaocun Township, Xingyang City, Henan Province. From the site, more than 3 000 pottery moulds have been unearthed, with various types, including the moulds for containers, tools, chariots, weapons, money and core, etc. According to the types and decorations of pottery moulds and the characteristics of co-existing pottery, the pottery moulds of Guanzhuang site can be divided into two periods—Phase Ⅰ dating from the late Western Zhou Dynasty to the early Spring and Autumn Period, and phase Ⅱ considered between the early and middle Spring and Autumn Period. The change of bronze ware styles from the Western Zhou Dynasty to the Spring and Autumn Period was important in the development of ancient Chinese bronze wares. Due to the lack of archaeological data, research on pottery moulds during the two-week period was still insufficient; discussion of the important issue of standardizing the sources of raw materials was also relatively weak. Environmental archaeology has relatively mature methods and practices in depositional dynamics, depositional processes and provenance tracing, which could provide new ideas for further in-depth discussions on this issue. In order to understand the material sources and craftsmanship of pottery moulds unearthed from Guanzhuang site in Xingyang, Henan Province, samples of Guanzhuang pottery moulds and natural sedimentary strata were studied using particle size analysis, XRF and petrographic analysis to give the following results. 1) The raw materials for mould-making were taken from the late Pleistocene Malan loess layer under the cultural layer of the site. The Malan loess underwent simple manual elutriation before being used to make pottery moulds. 2) A small amount of plant ash and calcium nodule powder was added during the production process of pottery moulds as an admixture to increase the high-temperature resistance. 3) The inner side of pottery mould for container was mainly made of Malan loess, while the outer one was made of a mixture of Malan loess and river sand with a blending ratio of about 7∶5. Pottery moulds for various ware types had different processing techniques (e.g., moulds for containers were more refined). Besides, compared with early pottery moulds, later ones are relatively rougher, but the difference is not obvious. 4) The petrographic characteristics of double-layer container moulds indicate that there are different production processes for the inner and outer sides of mould. The inner side was made of Malan loess with finer particles—below 100 μm—as the raw material after elutriation, and there were traces of directional trimming. The outer one was made of a mixture of two parts of minerals (coarse and fine), and there was no obvious processing trace. Analysis of sample particle size is a new attempt to discuss the material sources of pottery moulds. The related discussion of mud-clarifying ponds is also helpful to understand the function of such relics and the formation process of accumulation in them. This study has important reference significance for exploring the material and craft characteristics of pottery moulds before and after the early Spring and Autumn Period in the Central Plains.

Abstract:In April 2021, several exquisitely decorated figurines of Heavenly Kings were unearthed from the Tang Dynasty tombs of Su Tong’s family in Xianyang, Shanxi Province. However, for each figurine, the outer side was unevenly red and black, and the center and interior of the body black, and the mechanical properties extremely poor (disintegrated by water). To scientifically restore and conserve the polychrome pottery figurines of Heavenly Kings, we carried out scientific analyses of their materials and their firing process. The composition, structure, firing temperature and mechanical properties of the figurine remnants were determined and analyzed using an X-ray fluorescence spectrometer, an X-ray diffractometer, a simultaneous thermal analyzer, a thermal dilatometer, an X-ray photoelectron spectrometer, a universal testing machine and a hardness tester. The experimental results show that 1) the figurines were made of fusible clay containing quartz, albite, calcite, muscovite, clinochlore and other minerals; 2) the figurines were sintered between 300~400 ℃ in an oxidizing atmosphere, the internal sintering degree being lower than that of the external surface and the uneven atmosphere leading to the differences in color among various parts of a figurine; 3) the mechanical strength of the figurines was low, with a flexural strength of about 2 MPa and a hardness of 54~71 HD. The study provides a scientific basis for the effective conservation and reasonable preservation of the polychrome pottery figurines of Heavenly Kings and of other similar kinds of cultural relics.

Abstract:In order to analyze the lacquering process of NanhaiⅠ lacquerware, we took three pieces of lacquerware fragments from the shipwreck as examples to carry out systematic research using several analytical instruments including optical microscope (OM), X-ray diffractometer (XRD), scanning electron microscope-energy dispersive spectrometer (SEM-EDS), Fourier transform infrared spectrometer (FT-IR) and confocal Raman spectrometer (Raman), etc. The structures and production processes of the fragments were analyzed from the aspects of the number of lacquer layers, composition of color-developing materials, composition of lacquer films, structure and composition of lacquer ash and structure of the base. The results of Raman spectrometry show that the red color-developing material in the three fragments is cinnabar (HgS), the yellow one orpiment (As₂S₃) and the black one carbon black (C). The internal and external lacquer ash in the samples are common substances such as hydroxyapatite [Ca₅(PO₄)₃(OH)], quartz (SiO₂) and calcium oxalate hydrated [CaC₂O₄(H₂O)2.375]. The composition of the lacquer films is raw lacquer with a small amount of quartz particles, but without tung oil added as an auxiliary.

Abstract:For organic cultural relics such as paintings and textiles, a very typical fading problem is often discovered during their conservation and restoration. It is necessary to conduct mechanism research using scientific methodology since this is an irreversible change for dye molecules. Caesalpinia sappan L., known as sappanwood or brazilwood, is famous, worldwide, as a natural red dye, but it is very poor in light fastness. The aim of this research was to investigate the fading using accelerated photodegradation and speculate the photofading by-products in the form of simulated UV ageing experiments. The solution kinetics of brazilin and protosappanin B, which have been found in relics, were studied in solvent DMF, and 20 sets of UV accelerated ageing standards were obtained. The products were analyzed using UV-Vis diffuse reflection spectrometry, ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF MS) and proton nuclear magnetic resonance spectrometry (¹H NMR). These tools were applied together to analyze the color change trends and ageing process. 17 different photodegradation silk samples dyed with sappanwood were analyzed using UPLC-QTOF MS in the negative ion mode in combination with chemometrics. The results show that the fading produced a hypsochromic shift of max peak positions in their reflectance spectra with light ageing. The hydroxyl group of quaternary carbon in brazilin tended to dehydrate and made a series of changes while protosappanin B was easily converted into several compounds such as protosappanin C and urolithin C during the photoageing process. The simulated fading textiles dyed with sappanwood could be generally divided into two differential groups and differential metabolites including brazilin, protosappanin B and C could be analyzed through principal component analysis. These overall factors eventually caused the color change. These results are expected to be helpful to the research on natural dyes in textile heritages.

Abstract:The ventilation rate of a museum showcase is an important indicator for evaluating its sealing performance. In order to evaluate the ventilation rate of a showcase accurately, objectively and scientifically, some details of the detection and evaluation methods were comprehensively studied on the basis of GB/T 36110—2018. The results show that in order to achieve a better fitting effect, the carbon dioxide concentration outside a showcase should be fixed—a fixed concentration between 300×10-6 and 600×10-6 (volume fraction) had little influence on the fitting results. The average ventilation rate of the showcase at each moment was obtained by the numerical calculation method. When the detection time was short, values were unstable and fluctuated greatly; after stabilization, they were close to the fitted ventilation rates. The initial carbon dioxide concentration had a great influence on the fitting results of ventilation rate. The initial concentration of carbon dioxide gas in a showcase should be basically fixed between 20 000×10-6 and 25 000×10-6 (volume fraction) during detection, so that the testing results were comparable. The carbon dioxide mixture in the airtight showcase is relatively uniform, and no obvious dip occurred. The location of detection equipment has little influence on the fitting results of ventilation rate. If the fitted R² reaches 0.9, the results are considered valid, due to various errors in the detection process.

Abstract:At present, in terms of the conservation of archaeological sites, research is mainly focused on the application of emergency conservation measures and temporary consolidation materials, but there are relatively fewer reports on preventive conservation of archaeological sites. In the excavation and preservation project for the sacrificial pit at Sanxingdui site, a preservation system, consisting of archaeological excavation cabins, an environmental control system, an air-quality monitoring system, preventive conservation measures and an intelligent information-monitoring management platform, etc., was established. Before the excavation, through the earthen site-monitoring system and regional meteorological station, information of cultural relic burial environment and regional meteorology was obtained, to provide reference for setting interior environment of the cabins. During the excavation, various preventive conservation measures, such as temperature and humidity control, air sterilization and purification, limitation of the number of people in a cabin and fresh air ventilation, were taken to control the temperature and humidity in the cabin, reduce the amount of bacteria and fungi, lower the concentration of CO₂, and slow the dehydration process of relics (e.g., ivory objects), which effectively controlled the cracking, crisp powdering and mildewing of unearthed cultural relics, hence providing sufficient time for on-site excavations. The innovative exploration and practice of preventive conservation of the sacrificial pit at Sanxingdui site could guide the direction and set an example for the on-site conservation of important archaeological sites in the future.

Abstract:Under the condition of flat terrain, the spatial and temporal characteristics of the water content of Quaternary soil cover on the top of Yungang Grottoes are obvious:the periodic annual change and vertical decrease with the depth layer by layer (except in winter). The soil water content increases to store water in spring and summer and decreases to lose water in autumn and winter. In spring and summer, the soil water content increases during the day and decreases at night; in autumn and winter, it decreases both during the daytime and at night. The soil water content is constantly changing, affected by many factors such as temperature, atmospheric precipitation and micro-topography, etc. The shallow soil of the mountain slope may be the infiltration channel of the lateral saturated flow. The influence depth of rainfall on soil water content is inconsistent with the actual infiltration depth. The water contents of the roof and the upper and middle parts of the rock wall is mainly controlled by rainfall infiltrating the topsoil layer of the cave and seepage water entering the cave along rock fissure channels, while the water content at the bottom of the rock wall is more affected by the unsaturated zone in front of the cave and underground capillary water. Years of waterproofing practice have also shown that the seepage water of Yungang Grottoes mainly comes from the top of the grottoes and nearby areas. Anti-seepage drainage has always been the leading idea for the management of seepage water in Yungang Grottoes. It is suggested that regional treatment be carried out according to the topsoil depth, terrain feature and site distribution, to give full play to the anti-seepage effect of soil and reduce excessive intervention in the soil cover. Under the premise of anti-seepage effect, the material for the anti-seepage layer should have certain permeability to meet the requirements of water vapor circulation between the cave, cover layer and atmospheric environment.

Abstract:In order to do a preliminarily evaluation of the influences of light on banknotes issued during the period of the Republic of China and to provide suggestions for their exhibition and preservation in museums, eight banknotes were selected for light aging tests with LED light and natural light. The main pigments of the banknotes were determined using Raman spectrometry and X-ray fluorescence spectrometry. The results indicate that PR49:1, Prussian blue, lead chromate and carbon black were used. The red pigment (PR49:1) on banknotes faded fastest, while the other pigments had relatively smaller color changes. Therefore, it is necessary to control lighting to prevent the photo-degradation of banknotes, especially those containing synthetic organic red pigments.

Abstract:The principle of minimum intervention, one of the important principles guiding the restoration of paper relics, is to keep restoration to a minimum. The restoration of Ming Hongwu silver tickets collected in the Temple of Heaven adhered to this principle. Thin Edgeworthia chrysantha paper was used for restoration, not only for the primary purpose of paper reinforcement, but also to enhance the identifiability of the damage on the basis of retaining the original appearance. Because there are characters on both sides of the silver tickets, a storage setting was made by making a sunken shape and inlaying cardboard to protect the silver tickets. The front was covered using Edgeworthia chrysantha paper having high light transmittance as a paper curtain, which could be lifted up for easy display. Named “roller blind inlay”, this binding form can meet the dual needs of collection and exhibition. The restoration and storage method feature less paste consumption and a smaller bonding area. The protection concept could provide reference for the preservation of single-leaf paper documents.

Abstract:While traditional techniques are still used for the restoration of calligraphy and painting works, modern analytical technologies can also be included to achieve cultural relic restoration effects by following the relevant principles. This paper takes the restoration of a calligraphy work by Yang Jisheng in the collection of Fengxian Museum as a case to show how the combination of modern analytical technologies and traditional restoration techniques—by selecting suitable materials for restoration and conservation through the analysis of disease types, paper materials and mounting characteristics of the work—can achieve the best restoration effect.

Abstract:Terracotta warriors and horses in the mausoleum of the first emperor of the Qin Dynasty has been a focus of scholars’ research since its discovery. Many experts have done qualitative research on the facial features of terracotta warriors and horses, but there is a lack of quantitative evidence. In this study, the face recognition technology was used to quantitatively analyze the facial features of terracotta warriors. The analysis process included image preprocessing, face detection and screening, face feature extraction, face feature vector representation, face feature vector similarity calculation and face feature vector similarity analysis, etc. The facial features of the terracotta warriors were analyzed intuitively through the facial similarity Top-N of a single terracotta warrior. By analyzing the facial similarities of several terracotta warriors through thermal maps, it was found that ten terracotta warriors had “distinctive faces” and ten terracotta warriors had “common faces.” A histogram was used to visualize the facial similarity distribution of terracotta warriors, and a normal distribution law of facial similarity distribution of terracotta warriors was obtained. For the research on terracotta warriors, the face recognition technology provides a quantitative analysis idea, which can not only be used for the analysis of facial features and clothing texture of terracotta warriors, but also lays down a technological foundation for the quantitative analysis of facial features of larger-scale terracotta warriors.

Abstract:The brick-vault hall of Longchang Temple at Baohua Mountain is a representative of a series of Ming Dynasty brick-vault halls—a unique architectural heritage type in China. In order to evaluate the structural safety of this architectural heritage in earthquakes, we set up a three-dimensional finite element model to analyze its dynamic properties, seismic response spectrum and seismic time history in order to obtain the natural frequencies, modal modes, seismic effect, and seismic deformation and stress response. The results show that the structure of the hall features high symmetry and high torsional rigidity. The degrees of influence of earthquake on the vibration of the hall are as follows:roof, side walls and arch on the second floor, eaves of the first floor, side walls and arch on the first floor. Under the Intensity 7 frequently-occurring earthquake, precautionary earthquake, and rarely-occurring earthquake, the most dangerous position of the hall is the junction of the arched window impost and sill wall on the side far away from the stairs on the first floor. In addition, prone to the tensile damage, each arch impost is a weak position in an earthquake. Finally, a seismic strengthening strategy for the brick-vault hall of Longchang Temple is presented based on the results of dynamic properties and seismic behavior analysis.

Abstract:Hydraulic mortars are traditional construction materials with good properties. Compared with air-hardening mortars, hydraulic mortars possess better waterproofness, permeability, freezing resistance, salt crystallization resistance and mechanical strength, and are potentially ideal restoration materials for historical architecture. The present research reviews factors influencing the properties of traditional hydraulic mortars, including inorganic components (binder, aggregate and water), natural organic additives (polysaccharides, proteins, oils and fats), and curing conditions. For inorganic components, their influences on hydraulic mortars depend on both the properties of the binder and the proportions of the different inorganic components. For natural organic additives, addition of polysaccharides into mortars can improve their mechanical strengths, addition of proteins can increase their water resistance and porosity, and addition of oils and fats can greatly improve their water resistance and durability. As for curing conditions, hydraulic mortars cured under higher relative humidity can have better mechanical strengths, while those cured under low relative humidity are more durable. The present research intends to contribute to understanding the scientific values of traditional hydraulic mortars, and to developing new restoration materials for historical architecture as well.

Abstract:A panorama of laser cleaning methods for easel paintings is discussed in terms of applied laser types, laser-induced alterations on painting materials, as well as main application scenarios such as removal of surface deposits, treatment of aged varnish, removal of overpaint and cleaning of the backside of paintings. This overview article provides comprehensive reference for the selection of laser types and other operative parameters in practical terms by indicating typical working logics and procedures. Research gaps still needed to be filled are also indicated.

Abstract:Zooarchaeology directly pertains to the palaeoecological reconstruction of ancient sites, as well as human behavioral information on faunal resource exploitation. However, the conventional zooarchaeological method fails to identify the archaeological animal materials or artefacts without sufficient morphological characteristics. Zooarchaeology by mass spectrometry (ZooMS) is an approach of palaeoproteomics, which conducts species identification using mass spectrometry of enzyme digested peptides. In this paper, the fundamentals, methods and latest research progress of ZooMS are overviewed in order to promote its development in the field of archaeology in China. In addition, ZooMS also has great potentials in food, medicine, health product, leather, customs anti-smuggling and other related industries or tasks.

Abstract:This is a statistical analysis of the output and distribution of 10,768 publications as samples in five international journals. Using VosViewer software, knowledge graph analysis of research institutions, authors and key words was carried out, showing the themes and structures of scientific knowledge in the field of international archaeometry and conservation. Based on this knowledge system, ideas and suggestions for cultural heritage protection in China are put forward.