Abstract:Leather products have a long history of wide use in China, but due to their main components being proteins, lipids and other organic compounds, they are easily affected by burial conditions (soil, microorganisms and underground water, etc.) or museum environments (temperature, humidity, light, microorganisms and harmful gases, etc.) and thus suffer from a series of diseases (hardening, insect decay, rot, deformation, discoloration, damage and loss, etc.), among which hardening is the most common and serious. To explore the conservation methods for softening hardened leather relics, artificially-aged modern sheepskins were used as the samples to be softened by different formulae of softening agents. In order to compare the softening effects of different softening agents, the softness, mass and dimensional change data of leather samples before and after softening were tested, and the microstructures observed using scanning electron microscopy (SEM) were analyzed. The results show that the softening agents with the ratio of lanolin∶Span-80∶silicone oil∶water = 10∶1∶1.5∶50 and the ratio of lanolin∶SDBS∶silicone oil∶water = 10∶1∶1.5∶50 have obvious softening effects on the hardened leather samples, and could be widely used for the conservation of hardened leather cultural relics.

Abstract:Excavated in 1974, the Quanzhou Bay Song Dynasty shipwreck is the first large and early wooden sailboat for ocean trades excavated in China. It is not only a precious national grade-one cultural relic with important conservation value, but also a rare material for studying the history of China’s ancient overseas transportation, foreign trade and shipbuilding, etc. As a precedent for the conservation of large marine wooden relics in China and Asia, the Quanzhou Bay Song Dynasty shipwreck has been preserved for many years. After years of integrated conservation and restoration, the status of the shipwreck deserves attention. The action of microorganisms is one of the important biological factors causing wood degradation. The microbial hazard of wood is mainly caused by fungi such as wood-decay fungi, coloring fungi and molds, as well as some bacteria that can decompose cellulose. Therefore, the analysis of microbial communities in wooden cultural relics is not only an important strategy for the preventive conservation of wooden cultural relics, but also an important guarantee for efficient conservation to avoid the microbial hazard. In order to understand the population and distribution law of microorganisms in the currently preserved hull, samples from 25 different regions from the bow to the cabin and the stern were collected. Microbial high-throughput amplification sequencing was used to analyze the microbial composition groups and distribution laws of the hull, which is composed of different wood types, and to determine whether there were harmful, corrosive microbial groups in the current hull. The results of sequencing analysis show that there were stable and abundant microbial groups in all parts of the hull. Although there are some differences in the composition of bacterial and fungal communities in different parts of the hull, these differences are not significantly related to the wood type and structural position of the hull. The dominant bacterial species in different preservation areas of the hull are Acinetobacter sp. (13.65%), Bacillus sp. (6.88%) and Pseudomonas sp. (3.69%), and the dominant fungal species are Cladosporium sp. (12.26%), Candida sp. (5.93%) and Lophiostoma sp. (5.66%). In addition, the species of Bacillus, Streptococcus, Cladosporium and Aspergillus found in this study have strong abilities to degrade wood cellulose. The growth and outbreak of these microorganisms under certain environmental conditions will threaten the preservation of the hull. Therefore, in the subsequent conservation of the hull, the prevention and treatment to avoid the microbial hazard should be carried out regularly, and the temperature and humidity of the storage environment of the hull should be controlled strictly, so as to benefit the long-term preservation of the hull. This study systematically analyzed the microbial community structural composition of various parts of the Quanzhou Bay Song Dynasty shipwreck for the first time, and evaluated the risk of the microbial hazard for the public exhibition of the ship held by Quanzhou Maritime Museum Fujian, so as to provide an important reference for the following preventive conservation of the Song Dynasty shipwreck against microbial degradation in the future.

Abstract:Pu Du Ming Tai Zu Chang Juan, collected in Tibet Museum, is the earliest existing long scroll of the Ming Dynasty in China. At 4 968 cm long and 66 cm wide, it contains colorful pictures and detailed inscriptions. The pictures have lifelike descriptions of figures and architecture, and the inscriptions are written in five characters, showing rich historical and cultural value. Through a long history of more than 600 years, the long scroll had developed serious diseases and needed urgent conservation and restoration. In order to carry out the work scientifically and effectively, we made a comprehensive analysis of the mounting shape and technique for the long scroll, finding that it was generally mounted in a traditional Chinese mounting way. The exception is that the upper and lower edges of the long scroll were wrapped with red and green silk fabrics and the long scroll was backed with colorful Jiaxie, showing typical regional characteristics of Tibet. The red and green silk fabrics and colorful Jiaxie were used to reinforce the long scroll and also serve the function of decoration. They are a physical witness of the combination of Han and Tibetan mounting techniques. We also made a comprehensive assessment of the scroll’s main diseases, including wear, moth damage, fracture, crease, stain, pigment loss and improper restoration, etc. Fracture and pigment loss are related to the mounting shape. The texture of Jiaxie is rough and the red and green edge wrappings cause great thickness differences between the upper and lower edges of the long scroll and its middle part. This is why pigment fell off more seriously in the upper and lower areas than in the middle. Therefore, taking effective measures to reduce the continuous pigment loss while retaining the original mounting shape will be an urgent problem to be solved. Furthermore, we also made a comprehensive study of the painting and mounting materials using a variety of non/micro-destructive detection measures such as video microscopy, Raman spectrometry, portable X-ray fluorescence spectrometry, fiber optic spectrometry and hyperspectral imaging. The results show that 1) the painting paper of the long scroll (made from Edgeworthia chrysantha Lindl, flat and compact, with curtain lines which is unique to handmade paper), belongs to traditional Chinese handmade paper; 2) there are three kinds of raw materials used for the backing paper:mulberry bark, textured bark and bamboo; 3) the main color materials of the painting are mainly mineral pigments (mixed with plant pigments):the blue pigment is azurite, the green one malachite, the bright red one cinnabar, the pink one composed of lead white and a certain plant pigment, the orange one miniumite and a mixture of lead white and miniumite, the yellow one ochre, and the white one lead white. The pigment layer is thick but pigments have fallen off in some areas. The colorful Jiaxie and red and green edge wrappings were dyed with plant dyes such as hematoxylin, indigo and those from Sophora japonica. Plant dyes fade easily in water, so the fixation and cleaning methods need to be further studied before restoration. According to the comprehensive research, the historical value of the long scroll has been scientifically revealed, and its structure and materials clarified for the first time. The results could provide a scientific basis for the selection of materials and methods for its conservation and restoration in the future.

Abstract:The restoration of painting and calligraphy works made of special silks has always been a big problem. Because of the particularity and scarcity of materials, it is difficult to achieve ideal restoration effects if we cannot find the same kinds of silks. The painting material of a calligraphy scroll by Mo Jin of the Qing Dynasty is a kind of special silk treated with coating, dyeing, depicting and other techniques. Due to its improper preservation, serious breakage, loss of the filling material and other deterioration phenomena had occurred, and the scroll needed urgent restoration. However, it is difficult to find a similar kind of silk because of the special texture and color of the painting silk. In our work, after testing and analyzing the surface coating of the silk, referring to research literature and testing reports of traditional raw materials for ancient paper processing and combining aging tests of the materials, a mixture of porcelain clay and kaolin with a certain ratio was selected to replace lead white in the original coating as the filling material for this restoration. Finally, the repaired coating was retouched and an ideal effect was achieved.

Abstract:In order to investigate the technical characteristics of lacquerware unearthed from No.1 Shuangdun Tomb of the Western Han Dynasty in Lu’an, we analyzed the fragments of ear cups using a variety of modern analytical methods, such as ultra-depth-of-field 3D microscopy, Raman spectrometry, X-ray diffraction and Fourier transform infrared spectrometry. According to the experimental results:1) the ear cups consist of lacquer film on the internal surface, an interior plaster layer, the body, an exterior plaster layer and lacquer film on the outside surface; 2) the wooden body is made from Ulmus pumila L. and the textile fiber used for the ramie body is fibrilia; 3) the pigment for the red lacquer film is cinnabar; 4) the plaster layers of the ear cup with a wooden body are thin and delicate, containing quartz, albite and muscovite and 5) large particles of inorganic materials were found in the plaster layers of the ear cup with a ramie body, with the packing media being ashes of animal bones, quartz and albite. The ear cups with different bodies feature distinct technical characteristics.

Abstract:Located in Ganjingzi District of Dalian, Liaoning Province, Yingchengzi Cemetery of the Han Dynasties is a prominent Han cemetery in Northeast China. Several glass ear pendants were excavated from this cemetery. In order to explore their manufacturing techniques and sources, the micro-morphology was observed using an ultra-depth-of-field microscope, showing they were made by die casting and polished. Compositional analysis was carried out using a portable X-ray fluorescence spectrometer and the results show that these ear pendants belong to PbO-BaO-SiO₂ and K₂O-SiO₂ glass systems, respectively. One of them was colored with Cu²⁺ and the others were mainly colored with Co²⁺. They were made in China and share the same source of cobalt. The MnO/CoO ratios are consistent with those of domestic asbolite ores in China. The relationship between the shape and the chemical composition system of glass ear pendants from Yingchengzi Cemetery and the production mode of glass ear pendants of the Han Dynasties are discussed, to further strengthen the understanding of production and transmission of glass ear pendants in ancient China.

Abstract:A batch of Shang Dynasty bronze wares unearthed from Liujiazhuang site in Jinan was investigated in this study. Archaeological evidence shows that most of the bronze wares with inscriptions and national emblems are quite similar to those from Yin Ruins, indicating that in Liujiazhuang area lived a clan closely related to the Shang capital in the late Shang Dynasty. According to existing information, there have been achievements in the remnants of animals and plants, as well as lead isotopes of bronzes unearthed at the site. However, in general, scientific analysis data on the production process, alloy techniques and mineral material characteristics of these bronze wares are limited, and the relationship with the remains of Yin Ruins needs to be further discussed and analyzed. In this study, 29 bronze wares (56 samples) from three tombs at the site were selected as the research objects to analyze their microstructures, chemical compositions, lead isotope ratios, trace elements, in order to conduct comprehensive research in combination with archaeological data such as utensil shapes. A variety of analytical methods used included metallographic microscopy, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), VG Elemental multi-receiving inductively coupled plasma mass spectrometry and Liman Prodigy inductively coupled plasma atomic emission spectrometry. The results show that the majority of the bronze wares were tin bronze, lead bronze, pure copper, and lead-arsenic bronze. We propose that most of the objects were cast bronzes, with a couple showing signs of cold working after casting. Furthermore, the metallographic structure of most of the bronze wares is based on α solid solution with dendritic segregation and inter-dendritic distribution of (α+δ) eutectoids, some of which are totally corroded. Another obvious phenomenon was that Pb phase was granular and scattered or completely corroded, and irregular-shaped copper grains were precipitated between holes, branches and gaps. What is unusual about a handful of the utensils is that they feature slip lines in their metallographic structure, implying that they were cold-worked after casting. Moreover, the lead isotope ratio presents that this batch of bronze wares contains a relatively high proportion of lead of high radiogenic origin, which is consistent with the data distribution range of Phase Ⅱ and Ⅲ of Yin Ruins containing high radioactive lead artifacts but differs slightly from the distribution range of PhaseⅠand Ⅳ of Yin Ruins. Furthermore, their trace elements are characterized by high contents of Bi, As and Ag. These results are similar to the trace element distribution pattern of the bronzes from Yin Ruins. Last but not least, a thorough examination reveals that the primary raw materials of Liujiazhuang bronze wares and those from Yin Ruins seem to be the same. The shape and decoration style of Liujiazhuang bronze Ding, Gui and Gu are primarily related to the bronzes from Yin Ruins, notably PhaseⅡand Ⅲ of Yin Ruins, from the perspective of vessel type. As a result, we argue that the bronze wares unearthed from Liujiazhuang site resemble the ones dating back to PhaseⅡand Ⅲ of Yin Ruins. This study provides thorough scientific analysis of Shang Dynasty bronze wares from Liujiazhuang site and allows a further investigation of resource exchange between the Central Plains and Shandong during the late Shang Dynasty. According to the study, in the late Shang Dynasty, the Haidai area had significant ties to the Central Plains area where Yin Ruins are located, offering new evidence for the relationship between manufacturing and circulation of bronze wares in the late Shang Dynasty. Also, the study enriches our comprehension of Shang Dynasty bronze wares from Liujiazhuang site by supplementing and improving their scientific analysis content as well as archaeological research information, and provides a new perspective for an in-depth understanding of the relationship between the Haidai area and Yin Ruins during the Shang Dynasty.

Abstract:Archived as Ming Dynasty artworks, the funnel-shaped silver cups collected in the Palace Museum consist of 12 silver cups stacked together in sequence. Each silver cup is inlaid with black substance on the inside walls to form a decorative painting showing stories of some famous figures from various generations, with the name of a story annotated on the inside bottom, the name of the study marked on the outside bottom and some characters marked on one outside wall indicating the source of material for cup-making. Based on the background of a historical allusion—“lying under the urn in drink”, Zhang Li, researcher of the Palace Museum, has speculated that the set of silver cups were actually made in the Qing Dynasty.  In China, the decoration technique of inlaying a black substance on the surface of silverware is very rare. Some scholars call the process of inlaying black substance on silver cups “negative engraving with black lacquer”, and other studies have found that the decoration technique for silver cups is more likely to be niello-inlaying. In foreign countries, niello is referred to as a black metal sulfide generated at high temperature by sulfur and at least one or more metals, and is used to decorate metal objects such as gold, silver and copper wares. The process of applying niello to the surface of metal objects is known as niello-laying. In order to clarify the decoration technique for silver cups, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), X-ray fluorescence (XRF) spectrometry and X-ray diffraction (XRD) were used for the observation and analysis of one silver cup. The results show that the black substance was inlaid in grooves by melting with heat and polished after curing to make the surface flat, the black substance consists of Cu, Pb, Ag and S elements and the tested sample contains stromeyerite. The above indicates that the black substance is niello formed by silver/copper/lead sulfide and the decoration technique for the silver cups is niello-inlaying. According to the studies of related scholars, there are three different recipes of niello used for silverware in ancient China, among which niello of pure silver sulfide needs to be generated in situ on the objects, while niello of silver/copper sulfide and niello of silver/copper/lead sulfide need to be prepared first and then decorated on the surfaces of objects. In combination with the manufacturing method for niello on the silver cups, it is inferred that the process of inlaying niello on the surface of the cups is as follows:1) preparing niello containing silver/copper/lead elements; 2) powdering the niello; 3) filling niello powder into grooves or covering ornamental areas of the objects with niello (not powdered); 4) heating to melt niello and making it inlaid into grooves; 5) polishing after it is cooled.

Abstract:With the aim of treating soluble salt diseases in sand and stone cultural relics, we propose a method of using sodium octaborate to inhibit sodium sulfate crystallization. The inhibitory effects of gradient concentrations of sodium octaborate on sodium sulfate crystallization of sandstone from northern Shaanxi were studied using polarized light microscopy, scanning electron microscopy and X-ray diffraction. The results show that the greater the concentration of sodium octaborate was, the less sodium sulfate crystallized out. Taking into account the principle of “minimal intervention in cultural relic conservation”, a sodium octaborate solution with a mass fraction of 15% was selected as the best salt-inhibiting concentration. This research has important theoretical and practical significance for the treatment of soluble salt diseases and the conservation of sand and stone cultural relics.

Abstract:Local fresh sandstone samples from Yungang Grottoes, Leshan Giant Buddha and Dazu Rock Carvings were used to conduct one-dimensional capillary rise tests for distilled water. Evolutions of absorption mass and wetting front were obtained while local microstrain was measured by strain gauge rosettes in three directions on the surface of specimen at different heights. Macroscopic properties were analyzed in combination with microstructural characteristics. The results show that the whole process of capillary water absorption can be divided into three stages. The fastest and the slowest changes of capillary water absorption and capillary height with time are in Leshan sandstone and Dazu sandstone, respectively. The final values of local microstrain gradually increase for Yungang sandstone, Dazu sandstone and Leshan sandstone, which have differences in order of magnitudes. The variation trend of local microstrain is closely related to the movement of wetting front in that both the vertical and tilted (45°) strains show a contraction first, followed by an expansion. Pore size distribution and clay minerals are critical in influencing the capacity of capillary water absorption and hydric deformation. Such ability is very closely correlated with the formation of surface weathering diseases such as powdering, disintegration, cracking and flaking.

Abstract:As a novel temporary consolidant for extracting fragile relics from archaeological sites, menthol has been increasingly applied to many different relics at many excavation sites; however, after relics have been lifted and transported to labs, how to remove previously-used menthol quickly and safely becomes a new challenge. The most commonly-used removal method is to let menthol volatilize naturally, but water also volatilizes when menthol volatilizes. With the loss of water, waterlogged organic relics, which are sensitive to water loss, will have a shrinkage problem. In order to find safe technologies for menthol removal from waterlogged archaeological wood, two types of waterlogged wood relics from the Nanhai Ⅰ shipwreck—bark and rotten wood, which are extremely sensitive to water loss, were taken as examples in our work to test 5 different methods for menthol removal. These methods included natural volatilization, water supplementation+natural volatilization, removal by ethanol, removal by ethanol+water supplementation and water supplementation+heating. The appearance, mass loss and dimensional stability of the tested wood samples were evaluated to select safe methods for menthol removal from waterlogged archaeological wood. The results show that the method of water supplementation worked best for the bark and that of removal by ethanol worked best for the rotten wood. According to the removal effects, ethanol or a combination of ethanol and water are the best methods for the safe removal of menthol from waterlogged wooden relics. This study could provide technological guidance or a reference for archaeologists and conservators in terms of how to remove menthol after its uses for waterlogged archaeological wood.

Abstract:As a common material used for the restoration of murals, animal glue has the advantages of being non-toxic, pollution-free and compatible well with murals, but it also has the disadvantages such as poor water resistance and vulnerability to microbial erosion. In order to explore the performances of animal glue used for the restoration of murals, oxhide gelatin and gelatin (chemically pure) were selected and characterized as experimental objects in the laboratory. The results show that oxhide gelatin with a mass fraction greater than or equal to 1% and less than or equal to 3% has a high moisture vapor transmission rate, moderate adhesive strength and good permeability as well as little influence on the glossiness and chroma of murals, so it is more suitable for the restoration practice of murals in Mogao Grottoes.

Abstract:In order to determine the types of the conservation materials used for murals in two mausoleums of the Southern Tang Dynasty, we explored the distribution areas of the conservation materials on murals in Qin and Shun Mausoleums using multispectral photography, ascertained the location of the conservation materials from the ultraviolet fluorescence images and analyzed the materials using Fourier transform infrared (FTIR) spectrometry and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The results show that the main conservation materials used for murals in two mausoleums are styrene methyl methacrylate copolymer and polyvinyl acetate, as well as a small amount of polysaccharides, which may be glutinous rice juice used for the calcareous ground layer. This study indicates that the application of multispectral photography to provide clues and those of FTIR and Py-GC/MS to determine compositions compose a reliable analytical method system for tomb mural conservation materials. This system could provide a reference for the identification of conservation materials used for tomb murals, as well as a scientific basis for the evaluation of application effects of conservation materials on tomb murals.

Abstract:The mural of Men Lou Tu is the most complete, the largest and the most valuable one in the tomb of Murong Zhi. It is of great significance to study the burial custom of Tuyuhun, development of architecture in the Tang Dynasty and history of the relationship between the Tang Dynasty and Tuyuhun. Since its removal, with the changes of the body structure and preservation environment, the mural has been facing the threats of various diseases and thus needs urgent conservation. We took the mural of Men Lou Tu as the research object, analyzing the materials and techniques for the mural by studying its composition, and determining the status and causes through the study of its diseases. On the basis of the above research results, the typical diseases of the mural were scientifically controlled. According to the principle of preserving authenticity, restoration was performed with minimal intervention, and was carried out in the following order:back conservation-restoration—front conservation-restoration—aesthetic restoration. After the restoration, the stability, integrity and artistry of the mural have been significantly improved. This research not only lays a foundation for the conservation display and value extraction of the mural in the future, but could provide a reference for the conservation and restoration of other similar murals as well.

Abstract:Cultural relic reproduction is an important foundation for the conservation, inheritance and development of cultural heritages (especially super-large immovable cultural relics). The development of emerging technologies such as 3D laser scanning and 3D printing provides new ideas for cultural relic reproduction. Taking Cave 18 of Yungang Grottoes as the research object, this study explored and established a high-fidelity copying technology system for super-large cultural relics, which mainly includes high-fidelity data acquisition, 3D reconstruction, model block, printing and installation as well as high-fidelity paint printing. This method has been applied to the high-fidelity equal-proportion reproduction project of large-scale grottoes such as Cave 18 of Yungang Grottoes. The results show that the method proposed in this study can realize the high-fidelity equal-scale reproduction of large-scale grottoes, and the reproduction performances met the requirements of movement. This method could provide some reference and guidance for the conservation of similar cultural heritage objects.