Abstract:Piece-mold casting was a unique means for bronze manufacture in ancient China, and cast-on was a kernel technique for big and sophisticated objects. Nevertheless, it was ignored till the middle of the 20th century since R. Gettens recognized cast-on in the Freer Gallery of Art by cutting first and then through X-radiography, even though the later method was limited by object shapes. Industrial computed tomography (CT) employed to examine Chinese bronzes since 1980s, which has not only broken through the limitation but also contributed more discoveries. A series of phenomena such as ring-shaped tenons, pins and welding, etc. in cast-on have been discovered by CT examinations in both Japan and China. This paper briefly reviews the history of studying the cast-on of Chinese bronzes including the changes of methodologies, reveals the value of radiography and emphasizes the importance of problem consciousness as well as creative theory, method and facility.

Abstract:X-radiography has been used more and more widely in archaeometry and conservation, providing information not visible or unable to be gained by other analytical methods. In this paper, case studies of metal artifacts and bronze-casting ceramic mould fragments are reported in order to show the role X-radiography can play in laboratory excavation, conservation and technical studies of artifacts. The results reveal the current conditions and unknown restoration histories of some important Chinese bronzes in the British Museum collection, as well as the manufacturing process and methods of joins between different components of a complex object, and show, for the first time, the complex structure of ceramic moulds from the Houma foundry site. X-radiography, including conventional X-radiography and X-ray computed tomography (X-CT), is one of the most important analytical techniques used in the fields of archaeometry and conservation. It can provide constructive advice for the conservation and preservation of antiquities, produce scientific data for the interpretation of manufacturing techniques of objects and provide guidance for further studies of the objects.

Abstract:In Japan, scientific research on cultural properties is conducted using optical methods without sample destruction. For this purpose, many X-ray computed tomography (X-CT) systems have been introduced, mainly at national museums. This paper introduces the history of the introduction of CT systems in Japan and examples of their utilization.

Abstract:Over the past fifty years, various complex interdisciplinary diagnostic plans have been implemented in Italy during the execution of conservation projects on stone sculptures and on large bronze sculptures. Within this framework, radiographic examination techniques have been increased. The radiography, a non-destructive methodology that considers the work of art at the macroscopic level, has maintained a central role within the diagnostic phase, both for the purpose of reconstructing the ancient art techniques and procedures and to evaluate mechanical and structural aspects.  The history of studies is presented, considering the different radiographic methodologies: use of medium-energy X-rays, high-energy X-ray applications (linear accelerators), use of gamma radio-isotopic sources (gammagraphy).  The study describes the results achieved in important cases in the history of stone and bronze sculptures, among which the case study of the equestrian monument of Marcus Aurelius assumes particular relevance. The essay also describes the first application of “high-energy X-rays” involving the Majesty Group of Orvieto Cathedral, which is composed of the Madonna and the Child, two groups of angels and a bronze canopy. The concluding part of the essay defines the methodological criteria necessary for the correct interpretation of the results, in particular, with regard to the radiographic examination of the bronze sculpture, the correlation between the information derived from that examination and the casting procedures, with particular consideration of the casting defects and discontinuities.

Abstract:Industrial computed tomography (CT) can non-destructively analyze the structural composition, material distribution, density variation and other internal information of an object, and is one of the common methods for non-destructive analysis of the structural characteristics and material distribution of cultural relics. Due to the variety of materials, shapes and thicknesses of cultural relics, the scanning results of industrial CT can be accompanied by certain artifacts which will seriously worsen the image quality, and even make it impossible to accurately determine the internal structure of cultural relics. Artifacts in CT imaging originate from various factors:artifacts caused by physical factors are related to the CT projection data acquisition process; artifacts caused by sample factors are related to the placement, structure and material of the sample; artifacts caused by CT reconstruction algorithms are related to the CT equipment scanning method and its algorithms in the software. Some of these artifacts can be reduced by software calibration, but in many cases, proper sample placement and selection of appropriate CT scanning parameters is one of the best ways to reduce CT artifacts.

Abstract:X-ray micro-CT is a nondestructive analysis method, which has been widely used with good results in the fields of medicine, materials science and geology, etc. In our study, micro-CT technology was used to detect the microstructures of crown ornaments unearthed from the Kunlun Company M2 of the late Sui and early Tang Dynasties in the eastern suburb of Xi’an and from the tomb of Yan Shiwei and his wife of the Tang Dynasty at Majiagou, respectively. High-resolution three-dimensional structure CT images were obtained. They clearly show the structure of the ornaments such as the gilding layer and patterns as well as the connection methods. The interpretation of the decorative part structure shows that the gilding is the last procedure in the processing of ornaments and their accessories. It is concluded that micro-CT is of great practical significance to the study of the structure and processing of ancient products, especially small and badly deteriorated ones, as well as the evaluation of their preservation status.

Abstract:The process of metal corrosion is not only affected by external factors such as the environment, but also internal factors such as manufacturing techniques, alloy compositions and defects. Seeking for visualized approaches to researching the manufacturing techniques and internal corrosion conditions of metal artifacts, we used X-ray micro-CT to scan and detect a fragment of a bronze mirror and samples of archaeological and marine archaeological iron objects. Measures of XRF and XRD were also used to complement a comprehensive analysis of the component materials, manufacturing techniques and corrosion extents of metal objects. The results show that, based on micro-CT image reconstruction, the internal information of artifacts such as internal defects and corrosion extents could be measured and counted by setting different thresholds. This work provides a nondestructive research method for the study of alloy materials and manufacturing techniques as well as the corrosion assessment of metal artifacts.

Abstract:The application of radiographic flaw detection technology to bronze cultural relics began in the 1950s. With the continuous improvement of the accuracy of computed tomography (CT) technology, the high-precision industrial-grade CT system integrates modern radiographic detection technology, automatic control technology and computer processing technology, and has shown increasingly obvious advantages in the conservation and restoration of bronze cultural relics. In the case of the restoration of a Spring and Autumn Period bronze Ding unearthed in Nanjing, high-precision industrial CT technology was applied to the restoration of a traditional bronze cultural relic, and the detection image data were combined with visual augmented reality (AR), in order to provide a more accurate basis for the formulation of restoration plans and also a more intuitive and convenient operating environment for restoration intervention. The application of X-CT combined with AR technology is a new addition to traditional bronze restoration techniques.

Abstract:The morphological structure, composition and technical characteristics of the gold-inlaid decorative patterns on Warring States bronze chime bells collected in Sichuan Museum were investigated using optical microscopy, scanning electron microscopy, and non-destructive X-ray detection, etc. Analysis of the morphological characteristics revealed obvious grooves on the surface of the chimes, which were filled with gold wires. Gaps were identified on the surface of gold wires, some of which showed smear marks and edge sagging marks. In addition, gold particles were found on the substrate near ornamentation. No processing traces such as beating or cutting were identified on the surface of gold wires, indicating a significant difference between the gold wire decorating the chimes and that used in the traditional inlaying process. The results of gold wire composition analysis indicated that the Au content was greater than 91.6%, Ag 1.0%~4.0% and Hg 0.5%~6.0%. In addition, a large number of pore structures can be seen in the sections of the gold wires. On the basis of the morphological characteristics and composition of the gold wires, it was speculated that the chime was decorated using a gilding technique, and the purpose of the groove was to improve the adhesion of the gilding. This work not only provides valuable data in support of the study of bronze decoration crafts in Bashu area but also provides important physical materials for the study of ancient bronze decoration crafts in China.

Abstract:In our work, X-ray computed tomography (X-CT) was used as the main research measures to interpret the structure of a cloisonné enamel ware with an inscription of “Jingtai” from the Palace Museum. In combination with the results of X-ray fluorescence and Raman spectrometry, it is found that each part of the enamel ware came from different relics. The thickness and color of the glaze layer, the structure relationship and elemental compositions all point to a later-remade object, confirming what experts have previously deduced from visual inspections.

Abstract:The observation and analysis of the internal structure and surface fluctuation of lacquerware in cultural heritage objects is an important way to explore the causes of the formation of diseases on these objects and to understand the traditional techniques used to produce them. X-ray computed tomography (X-CT), applied in this study may achieve nondestructive detection of cultural heritage objects. Being able to penetrate the surface of an object, X-rays can therefore render clear and precise images of its inside. Based on this technology, we can obtain new understanding of the original production methods and the state of preservation of an object. Through the interpretation of the X-radiographs of a lacquer box, we analyzed its body structure and the causes of its damages. We also compared the differences in the production of lacquerware bottoms with historical literature. Finally we tried to display its wooden-body structure intuitively by reconstructing 3D model pictures. The study of lacquerware production techniques and surface diseases is conducive to analyzing the influences of different lacquerware production techniques on their diseases. The related results could be used to analyze the damages to the cultural heritage object and make rigorous scientific plans for subsequent restoration in a specific way. The data could also provide a scientific guidance for the research on production techniques and conservation of cultural relics in the future.

Abstract:Fengguo Temple in Yixian County, Liaoning Province is one of the three existing Liao Dynasty temples in China. The painted clay sculpture group in the Great Buddha’s Hall is a representative of Liao Dynasty clay sculptures, and boasts a history of more than one thousand years. At present, these sculptures have such problems as tilting, cracking of the mud layer and exposure of the wooden skeleton, which urgently need conservation and restoration. In this study, the non-destructive method of X-radiography was taken to investigate the internal structures, disease development and repair traces of these clay sculptures. The results provide a considerable reference for the future preservation work. In addition, the advantages and disadvantages of X-ray film imaging and computed radiography are compared, and the influencing factors of clay sculpture X-radiography are discussed, which have certain reference value for the applications of X-radiography to other cultural relics.

Abstract:The technological system of cast iron and steel-making was established and consolidated during the Warring States Period, Qin and Han Dynasties. Iron-making refractory materials provided structural, chemical and thermal stabilities in the ancient cast iron and steel-making productions. However, compared with metal and slag research, there is a lack of research on refractory materials. We carried out a comprehensive study, based on literature and field investigations as well as scientific analyses, especially the petrographic analysis. According to the petrographic analysis, it is believed that 1) rammed clay or stacked clay bricks were used to build the furnaces in early imperial China and 2) the sand material was rarely used, and the composite materials of clay, sand and rock fragments were not presented yet. In addition, the microstructures of the furnace materials, casting moulds and tuyeres (furnace nozzle) were very different, which shows that craftsmen during this period could make different refractory materials according to different performance requirements for different components of the iron production process.

Abstract:Computed tomography (CT) technology has the advantages of high resolution without the limitation of work piece materials and can obtain its three-dimensional digital information without damaging an object. Therefore, it has broad application prospects and great potential for development in the field of cultural relic digitization. However, in the process of CT scanning and image reconstruction, there are some problems including system geometric parameter deviation and ray hardening, which will lead to the decline of the quality of scanning images and the limitation of the accuracy of digital models of cultural relics. In order to solve these problems, we propose a parameter calibration and hardening correction algorithm based on scanning data, and carried out CT scanning experiments on two cultural relic replicas in our study. The experimental results show that the quality of the scanning images is significantly improved, the phenomena of ghosting and artifact are effectively suppressed, and the reconstructed digital models can clearly and completely restore the morphology of the objects. This method can be widely used for the CT digitization of cultural relics, which is conducive to the replication, conservation and display of cultural relics and the communication of cultures. It has strong scientific and social economic significance.

Abstract:This study is focused on an archaeological site composed of stone and soil. Based on the determination of the permeability of stone and soil, the environmental conditions of wet and dry deterioration are quantitatively evaluated by digital volume correlation (DVC) and digital image correlation (DIC), and environmental adjustment methods to control the occurrence of such deterioration are proposed. In order to collect basic data, experiments were conducted to analyze the amount of displacement of TOYOURA silica sand from wetting to drying by DIC and X-ray imaging technology. In the experiment, the deformation distribution of the samples under shrinkage stress was calculated using DIC. In addition, this experiment was conducted to evaluate the applicability of iron powder as a tracer by using iron powder as a reference point to calculate the amount of displacement in a specific range of TOYOURA silica sand. The results show that the deformation distribution before and after drying could be calculated by taking X-ray transmission images of the samples before and after drying and analyzing them with DIC. The addition of the tracer to the samples was also found to be useful in analyzing the direction and amount of movement in localized areas of the samples. Therefore, through the application of this technology, it is believed that it could be used to elucidate the deterioration mechanism of dry-wet cycle weathering in the future.

Abstract:In our work, the mature solidification theory in metal materials science is introduced, and the process for casting of ancient Chinese bronzes is systematically studied. ProCAST software is used to simulate the solidification process of bronze alloys and the process of solidification and formation of defects and their locations are observed in the dynamic visual level, so as to explore the mechanism of defect formation. In this study, four elements of the process of solidification of ancient Chinese bronzes are summarized:material preparation, temperature control, solidification time and defect mechanism. The introduction of simulation methods based on modern solidification theory enables us to examine the casting techniques employed for ancient Chinese bronzes using a new calculable simulation technology. This technology provides important support for the scientific interpretation of ancient Chinese bronze casting techniques and the reflection of ancient Chinese metal technical achievements.

Abstract:Through the detection and imaging using computed tomography (CT), it is found that 1) there are 26 components of the Chen Zhang round pot, instead of the 19 described in the original archaeological report; 2) the body of the sword of Liao (king of Wu) has been seriously corroded and the inscription on the sword was cast rather than engraved afterwards; 3) the state of a bronze plate of the Spring and Autumn Period before its restoration is clearly visible. It can be seen that the CT technology can play a key role in revealing the casting process of ancient bronzes, identifying the authenticity of bronzes, and inspecting the technological routes of conservation and restoration.