Abstract:Based on the principle of “wood bone and clay body” used to make clay sculptures found in the Dunhuang grottoes and the methods of testing adhesive strength of coatings and binders, a fixture has been developed for directly evaluating the surface adhesive effectiveness of wall painting conservation materials at the interface between the paint layer and the plaster layer and between the plaster layers. The invention of this fixture has solved such problems as adhesion interface mismatch, lack of objective data, poor application and low efficiency in evaluation of the surface adhesive effectiveness of the conservation materials. In our study, we determined the adhesive strength of six commonly-used conservation materials with mass concentrations of 5%; the sequence from the strongest to the weakest is as follows:pure acrylic emulsion＞PVA-1788＞PVAC emulsion＞silicone-acrylic emulsion＞gelatin (Paraloid b-72). According to the experimental data, it is proposed that selecting conservation materials and working concentrations should consider the proximity to the adhesiveness of original binding materials (gelatin), the closer the better.

Abstract:Located in Qingshuihe County (in southern Inner Mongolia), Ta’erliang tomb mural paintings can date back to the Five Dynasties and Ten Kingdoms periods. In our study, we examined the pigment layer, white underground layer and plaster layer of five fallen fragments, with the aim of investigating the composition of the mural painting materials. The methods used in this study include optical microscopy, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and Raman spectrometry. The results show that 1) the red pigment is mainly ferric oxide, the yellow pigment hydrous ferric oxide and the black and grey part graphite-structured carbon black; 2) the main composition of the white ground layer is calcite; 3) the plaster containing quartz, calcite and feldspar also shows some white grains identified as lime, which suggests that lime was added into the plaster to improve its cohesion; 4) The track and the plant opal inside the mud layer indicate that natural fibers of wheat leaves and wheat shells were mixed in preparation for making the plaster layer. According to the analytical results for the materials, the mural paintings were probably made through the following procedures:lime was added into the mud which had been mixed with plant fibres to make the ground layer, and then white lime was brushed on it. The paintings were finally drawn on the top of the plaster layer.

Abstract:The traditional freeze-drying process usually requires the insertion of a resistance temperature sensor (RTD) into the material to monitor the temperature variation and determine when drying has been achieved. However, this technique often causes damage to wooden relics in terms of conservation. In this study, we analyzed the real-time concentration of the dimensional stabilizer agent impregnation solution and were able to predict the end point of freeze drying in a nondestructive way. Using this method, we conserved 30 fragments of wooden structural components excavated at the Zhidanyuan Sluice Site of the Yuan Dynasty by vacuum freeze drying, achieving the desired effect of shape protection and ensuring the safety of these wooden components as well.

Abstract:Many excavated waterlogged wooden cultural relics suffer from degradation and have very high moisture contents due to the organic components they contained; because of this, they can easily collapse, crack or deform during the drying process. Therefore, study of dehydration technologies for waterlogged wooden cultural relics has become an important topic in the conservation field. In order to study the effectiveness of the air-cooled drying method, we conducted experiments on a collection of waterlogged wooden cultural relics. After identifying the species of wood and determining the moisture contents, basic densities and chemical compositions, we used an air-cooled refrigerator to freeze-dry the selected samples at -18℃, recorded the required time and effects of this drying method and analyzed the heat and mass transfer characteristics at a basic level. We conclude that the air-cooled drying method gives good results and has wide applicable for dehydration of waterlogged wooden cultural relics. In addition, it is also characterized by low costs and easy handling.

Abstract:In order to reveal characteristics of the origin and causes of diffusion of cobalt (Co) materials used in early Ming Dynasty blue-and-white porcelains, four blue-and-white porcelain shards from the early Ming Dynasty and five blue-and-white shards made in Western Asia were analyzed by energy-dispersive X-ray fluorescence (EDXRF) and laser-induced breakdown spectrometry (LIBS). The results showed that the cobalt materials used for early Ming Dynasty porcelains in Jingdezhen are very similar to those for Western Asia blue decoration in glazes, in that both are boron (B)-containing and low-manganese (Mn) cobalt materials. This work reveals not only the relationship between the cobalt materials used in early Ming Dynasty blue-and-white porcelains and Islamic Blue decoration materials from a new perspective, but also that the cause of diffusion of cobalt materials used in early Ming Dynasty blue-and-white porcelains is the pre-fused borax cobalt glass materials which have high sodium (Na) and calcium (Ca) but low aluminum (Al) and silicon (Si) contents. This work may provide an important reference for further studies on the origins of cobalt materials used in blue-and-white porcelains of the Yuan and Ming Dynasties.

Abstract:The Song Dynasty polychrome Arhat statues from the Magic Cliff Monastery, praised as No.1 statues throughout China, are highly valuable in terms of archaeology, art and technology. In this work, we analyzed the pigments of two selected statues using optical microscopy (OM), Raman spectroscopy and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS).It was found that the statues had been repainted several times, at least six. The pigments used are:carbon black for the black pigment; cinnabar, lead red and a mixture of cinnabar, mars red and calcite for red pigments; emerald green, Scheele’s green, clinoatacamite and a mixture of clinoatacamite and lead white for green pigments; a mixture of lead chrome yellow and lead red for orange pigment; azurite and ultramarine for blue pigments; lead white and calcite for white pigment; mars yellow for yellow pigment. The gelled patterning was made of lime. The components of the white layer are lead white and white soil with the elements of silicon (Si), aluminum (Al) and calcium (Ca). It can be concluded that using white soil for white layers and repainting collar edges by gelled patterning and gilding are traditions of the monastery. Judging from the presence of modern colorants, synthetic emerald green, chrome yellow and Scheele’s green, it is also suggested that the last repainting may have been executed at the end of the Qing Dynasty.

Abstract:In order to determine the corrosion products of the late Warring States Period iron wares unearthed from the City Site of Zheng and Han States (Zheng Han Gucheng), 13 iron samples with corrosion products were studied using a variety of methods including X-ray diffraction (XRD) and metallographic microscopy. The results indicate complicated mechanisms, diverse components and obvious stratification of the corrosion products. Some iron wares also contain active corrosion products. This study also indicates that preservation states of iron wares have a close relationship with their metallographic structures.

Abstract:The origin and ingredients of Kaihua paper used for imperial printed books of the Qing Dynasty have long been controversial issues in the academic world. In recent years, some scholars have compared archives and existing ancient books, finding that the Qing Dynasty “Kaihua paper” is actually “Liansi paper” and that “Kaihuabang paper” actually “Jingxianbang paper”. Both papers come from Jingxian County of Anhui Province. In our study, we analyzed the fiber micrographs of the residual fragments from four kinds of Kaihua paper and one kind of Kaihuabang paper, and compared the microscopic features of the ancient samples with those of a control sample from the perspectives of fiber morphology, fiber width, fiber grain, gum coating and crystal morphology. The results suggest that the fibers of the five residual fragments are all derived from wingceltis bark only, which is consistent with the results of research on historical materials. According to the mutually-verified conclusions, the so-called Kaihua paper and Kaihuabang paper used for imperial printed books of the Qing Dynasty could well be wingceltis paper from Jingxian County, Anhui Province.

Abstract:A scroll is a unique form of display and collection for painting and calligraphy. However, creases on the surface of a scroll painting not only affect its appearance during exhibitions, but also reduce its lifetime. In our study, microstructures of scroll painting creases were analyzed by hyperfocal microscopy and scanning electron microscopy (SEM). We also discuss the mechanism of crease generation and propose a corresponding preventive measure. The results indicate that rolling-up with small winding diameter is one of the major causes of scroll painting creases. A smaller winding diameter makes that phenomenon more obvious. Generation of scroll painting creases and fiber breakage can be effectively reduced by addition of an axle tube, which increases the diameter of the winding rod. This proposed method can maintain traditional mounting forms and original appearances of paintings, and also preserve traditional charms of the art of painting and calligraphy.

Abstract:This paper describes a method to detect defects on stone sculptures and timber compoments of ancient architectures with an ultrasonic CT system. This system contains an outside amplifier for weak received signals, a multi-sensor fixing apparatus, and sensor diameter converters. The converters transform the diameter of sensors from 50 mm to 10 mm, to decrease the error caused by inaccuracy of the location of both the transmitters and receivers. No coupling agent is used during the detection, to avoid artificial damage to the detected objects. We analyzed three standard wood samples and obtained the images that correspond to the appearances of the samples. Satisfactory analyses of four pillars of two buildings of Western Mountain Temple were also obtained.

Abstract:Existing studies of rainfall erosion classification focus on the static destructive effects of multiple rainfalls, with the aim of identifying the disease and determining its main causes. In order to study the relationship between rammed earth site erosion and rainfall, and to explore the dynamic developing process of rainfall erosion, we conducted an investigation into the rainfall erosion on the Ming Dynasty rammed wall in Yuyang District. Through classification and statistical analysis, we propose that the basic rainfall erosion models are dry-wet erosion, scouring erosion and collapse erosion. Proposal of the three models provides a new viewpoint for studying the dynamic response relationship between rammed earth site erosion and rainfall.

Abstract:Chinese culture has a long history and has left us a lot of stone relics with historical, artistic and cultural values. In recent years, the Chinese Government has established requirements for the protection and utilization of cultural relics and also for the protection and inheritance of cultural heritages. Therefore, more and more attention is also being paid to protection issues of stone relics. Besides human destruction and surface contamination, more damage to stone relics is caused by natural weathering, erosion and corrosion due to factors such as sunlight, rain, wind, sand, surface water, underground water and earthquake, etc. We studied the diseases of the outdoor stone cultural relics, Yanghuayan Lithoglyphs (one of the 6th batch of National Key Cultural Relics Protection Units) using two nondestructive methods, namely surface nuclear magnetic resonance (SNMR) and ground penetrating radar (GPR). The SNMR method successfully detected distribution of water in the rock mass where the lithoglyphs are attached. The development of karst and fractures of the rock mass was detected by the GPR method. The results indicate the development of karst and rock mass fractures and also show that the karst and fracture zones of some parts have become a gathering place or circulation channel for underground water, which results in severe threats to the lithoglyphs. The results of these two methods are mutually verified and thus provide reliable data for the protection and disease management of the Yanghuayan Lithoglyphs.

Abstract:Fiber optic reflectance spectroscopy (FORS) is a nondestructive pigment identification method, so it is suitable for research on delicate and precious polychrome objects. The use of FORS has developed quickly internationally for research on cultural relics, but it is seldom applied in China because of the lack of a database. In our study, we investigated the effects of pigment granularity and provenance on reflectance spectra, summarized the reflectance spectral characteristics of blue, green, red and yellow pigments and used these characteristics to identify the pigments in architectural paintings and Chinese paintings at the Palace Museum. The results indicate that FORS is a quick and effective nondestructive pigment identification method.

Abstract:In this study, X-ray fluorescence (XRF) spectrometry, a nondestructive analytical method, was used to test and analyze the components and structures of five Qijia culture jade samples from Ningxia Museum. The analytical results show that the elements and their respective contents of the five samples are similar to those of Hetian jade. Furthermore, based on historical information about the Qijia culture, it can be inferred that the samples are made of Hetian Jade. We also made a comparative study using laser Raman spectrograms of the five samples and a Hetian jade sample. The result shows that their highest and second highest characteristic peaks are mostly similar. The peak of tremolite is quite clear in the spectrogram, which confirms the XRF result. The study provides a vital scientific basis and accurate data support for further research on materials and on the origin of Qijia jade.

Abstract:The restoration of porcelain relics can only be completed through multiple processes. The parts restored may show different degrees of surface discoloration in just 1~3 years. In order not to affect exhibitions, discolored porcelain relics often have to be restored again. However, multiple restorations may cause some damage to porcelain relics. Using some traditional restoration materials for porcelains as study objects, we conducted analyses on material discoloration for the purpose of improving their durability. In our study, white porcelain plates were treated with traditional porcelain restoration methods and then subjected to various ageing treatments with:dry heat, wet heat and exposure to xenon lamp light. The samples were then characterized by color difference and glossiness. The results show that 1) tinted samples show the biggest color change and 2) the environmental factors causing discoloration are light and temperature. Therefore, restored porcelains should be kept at lower temperatures and away from light.