Abstract:Dimensional stability is one of the principal protection goals for waterlogged archaeological wood. Various materials, including natural resins, polyethylene glycol, sugars, glyoxal, etc., have been developed for dimensional stabilization of waterlogged archaeological wood upon drying. Recent studies demonstrated the excellent performance of organosilicon compounds, among which γ-mercaptopropyltriethoxysilane (MPTES) gave the best results. However, the interaction between MPTES and waterlogged archaeological wood has not been well explained. A further study on this topic might provide new insights into designing better consolidants for waterlogged archaeological wood. In this paper, archaeological pine wood (Pinus massoniana) from the Nanhai Ⅰ shipwreck was used as the research material, and the effectiveness of maintaining dimensional stability upon drying by MPTES and its mechanism are further explored and discussed through weight percentage gain, shrinkage, observation using SEM and FTIR techniques. The results show that:1) the samples treated by MPTES show desirable dimensional stability (3.5% volumetric shrinkage) and that the effectiveness of MPTES is confirmed at low weight percentage gains (around 50%); 2) the resultant silicone is distributed uniformly in cell walls rather than in cell lumina; 3) with an increase in treatment duration, the water content, or concentration, the absorption assigned to aryl ether decreased, which is negatively correlated to the weight percentage gains and related to the FTIR absorptions of silicone. On the basis of the above results, the reaction between mercapto group and lignin, as well as the consolidation mechanism of MPTES are discussed. It is proposed that the reaction between the mercapto group and lignin may be similar to the formation of organic sulfur in waterlogged archaeological wood buried in redox condition and the reaction mechanism of the initial step of the Kraft pulping process, which involves the formation of lignin quinone methides, catalyzed by acid or base, followed by the addition of mercapto groups, to form thioether structures. Due to the Si-OH and -SH groups in hydrolyzed MPTES, MPTES has multiple interactions with both lignin and cellulose, which help to build stronger interfacial bonding forces between wood components, and therefore increase the integrity and mechanical strength of waterlogged archaeological wood. In this study, the mechanism of dimensional stabilization of waterlogged archaeological wood upon drying after treatment with γ-mercaptopropyltriethoxysilane is proposed. It is further believed that introducing moderately reactive groups such as mercapto group can help increase the dimensional stabilization ability of WAW consolidating materials and may have promising research and application values in the future design and development of better materials for waterlogged archaeological wood protection.

Abstract:The evaluation indicator system of materials is an important aspect of materials research, application and promotion. It has important functions and meanings with regard to building measurement standards, regularizing parameters of material properties and promoting industry development. In the aviation, aerospace, automotive, construction engineering, paint and coating industries, relatively mature and complete evaluation indicator systems for various types of materials have been established and possess scientific and systematic indicator evaluation methods and relatively in-depth theoretical research. In contrast, the development of such systems for cultural heritage conservation and restoration materials, such as those used for evaluation and research on ancient mural conservation and restoration materials, is relatively slow, and the research basis is relatively lagging. This article analyzes the reasons of mural flaking (including various physical and chemical effects), and summarizes the international and domestic progress of study on evaluation of properties and adaptability of mural repairing materials (including a brief history of application of restoration materials). By using the model of “requirement-property-evaluation indicator” and analyzing the evaluation indicators and methods, an evaluation indicator system was proposed. The evaluation indicator system is divided into three categories—effectiveness, safety and durability—and includes fourteen items:cohesiveness, penetrability, water vapor permeability, fluidity, optical property, chemical inertness (including alkalinity or acidity), nonhazardous effect and ageing resistance to temperature, humidity, light, salt and microorganisms. The suitability, problems and difficulties of specific methods for the evaluation indicators are also analyzed. It is pointed out that murals are superimposed by the multiple effects of the main body (multiple materials, multi-layer structure) and the environment. And it is also explained that the craftsmanship (operation) developed from the restoration practice is also a special manifestation of the material requirements for mural restoration. Further optimization proposal of the construction of the evaluation indicator system by using mathematical modeling and analysis for mural flaking repairing material was presented. The proposed evaluation indicator system will provide a solid scientific foundation for the research, application promotion, and new material research and development of mural conservation and restoration materials.

Abstract:During the period of 2011 to 2013, a wall painting fragment was unearthed from affiliated building remains in Emperor Qinshihuang’s Mausoleum near Emperor Qinshihuang’s Mausoleum Site Museum. In order to understand the techniques and materials of the wall painting, polarized light microscopy (PLM) , Raman microscopy (RM), scanning electron microscopy and energy dispersive X-ray spectrometry (SEM-EDS), infrared spectrometry (IR) and X-ray diffraction (XRD) were utilized to analyze the pigments and the painting techniques. The results show that the wall painting is composed of a pigment layer, a finely ground plaster layer and a coarse plaster layer. The white ground layer is calcium carbonate limestone, the black pigment is black copper (melaconite) and the red outlining pigment is hematite. There is calcium carbonate in the plaster layer and plant stalk in the coarse plaster layer. This is the first time when a wall painting fragment was unearthed at Emperor Qinshihuang’s Mausoleum and this work is the first study of a wall painting of Emperor Qinshihuang’s Mausoleum. This study supplies important information about Emperor Qinshihuang’s Mausoleum and its affiliated building.

Abstract:In this study, the Keyence VHX-5000 ultra-depth three-dimensional spectrophotometirc system, the X-rite VS450 colorimeter and other related instruments were used to conduct surface observations and chromaticity monitoring on samples of Xuan Wu mural painting unearthed from the Tang Dynasty tomb of Han Xiu. The study found that the yellow pigment in the mural is a mixture of vanadium-lead ore and lead. The lead carbonate produced by the oxidation of lead in the tomb was further oxidized to lead oxide in the laboratory environment. With regard to chromaticity, research shows that the ΔE value, which shows the difference in chromaticity before and after reinforcement, is around 4.33, which is within acceptable standards.

Abstract:The development of glazed tiles has a long history in China. They originated in the Northern Wei Dynasty and were widely used in high-grade buildings in the Tang and Song Dynasties, and then flourished in the Yuan, Ming and Qing Dynasties. As a minority regime, Xixia stood side-by-side the Song, Liao and Jin Dynasties, and played an important transitional role in the development of glazed tile technology. The Xixia Mausoleum site is a typical representative of official architecture in the Xixia period. It is located at the eastern foot of Helan Mountain in the western suburb of Yinchuan city, Ningxia Hui Autonomous Region. After archaeological investigation and excavation, a large number of cultural relics, including a huge amount of architectural components were unearthed. These were mainly white porcelain tiles and various types of green glazed building components, and are typical representatives of official architecture. At present, many important achievements have been made in the research on the archaeological work and unearthed cultural relics of Xixia Mausoleum. However, the social functions of porcelain and glazed tiles of Xixia are mainly studied through archaeological typology and historical documents, and there is little research on technology. At the same time, the relevant technical characteristics and sources are also an urgent problem to be solved. In order to study the technological characteristics of official building materials in Xixia, 30 white porcelain and green glazed tiles unearthed at the site were selected for phase analysis and microscopic observation by X-ray fluorescence, X-ray diffraction and scanning electron microscopy. The results show that the content of Al₂O₃ in the body of white porcelain tile is high and that mullite is present. The glaze formula belongs to a fine calcium alkali glaze technology, close to that of the white porcelain of Lingwu kiln at the same time. It should be made by white porcelain technology. The green glazed tiles have high contents of CaO and Fe₂O₃ in their bodies, typical of the common high calcium fusible clay in the north. The glaze is lead glaze with copper as colorant, which is similar composition to the green glazed tiles of the Song Dynasty and which conforms to the traditional low-temperature lead green glaze system, which may be completed by using the technology of the central plains for reference. The tiles made of both materials are high-grade architectural components in the Xixia period and are typical representatives of official architectural materials. They co-exist, showing the diversity of official building material production technology in Xixia. However, the two technologies are quite different and come from different sources, which reflect that Xixia is inclusive in the production of official building materials, can closely combine Buddhist culture while learning the tradition of the central plains, and has the national characteristics of Dangxiang nationality. More importantly, the architectural system in Xixia has tended to be complex, and different glazed tiles may be used according to different parts, properties, grades and functions of the architecture, which is a great contribution to the enrichment and development of the architectural glazed system. Based on the analysis of scientific and technological archaeology, this paper explores the technological characteristics of official architecture in Xixia, and discusses the ideological ethics reflected by the manufacturing technology. This paper further enriches the research on porcelain and glazed architectural components in Xixia, forms a contrast with the glazed buildings in Song, Liao and Jin Dynasties, and supplements research on the glaze technology in ancient China. It not only deepens the understanding of Xixia official architecture, but also promotes the understanding of the cultural integration and mutual learning between Xixia and the central plains.

Abstract:Research on the mechanism of salt damage in Yungang Grottoes is of great significance to the selection of treatment strategies. In this paper, X-ray diffraction (XRD) was used to conduct semi-quantitative analysis of mineral composition and the acid-base neutralization method was used to determine CO₂ content, XRD was also used to conduct qualitative identification of salt minerals and silicate minerals, in an attempt to analyze damage patterns in weathered sandstone in Yungang Grottoes. The relationship with the salt precipitates associated with the rock surface. The results suggest that the flaky weathering of the rock face at Yungang Grottoes is related to the high carbonate content of the sandstone, and the powdery weathering is related to the high content of gypsum in the rock. The crystallization of different salts is related to the cave environment. These research results have reference significance for the treatment of weathering diseases in Yungang Grottoes.

Abstract:As the carriers of human wisdom and civilization, paper cultural relics such as manuscripts, documents and artistic works are non-renewable cultural resources and extremely valuable treasures of mankind. Unfortunately, a large number of long-stored paper cultural relics have been undergoing serious deterioration and discoloration due to the endogenous (pH, lignin, degradation products) and exogenous (light, heat, humidity, pollutant gases) factors. It is worth noting that the iron and copper metal species contained in some pigments and inks can cause serious corrosion and degradation of the paper. For example, the use of iron gall ink often produces perforation in inked areas due to the severe corrosion of paper. Moreover, the use of malachite (basic cupric carbonate) in traditional Chinese painting causes the yellowing or even embrittlement of nearby paper substrates; a remarkable yellowish-brown deteriorating edge can usually be observed near the green-blue pigment, which directly affects the readability and appreciation value of the art or even its stability in long-term preservation. The reasons for the damage of paper cultural relics containing iron/copper pigments are complex and diverse, and the reaction pathway and mechanism of degradation of cellulose polymers with iron/copper pigments are worthy of in-depth investigation. This article introduces the iron-based and copper-based pigments which are commonly used in paper cultural relics, including iron gall ink, Prussian blue, ocher, azurite, malachite, copper acetate, etc. We summarize three common routes of paper cellulose degradation, including acid hydrolysis, alkaline degradation and oxidative degradation. Then, we discuss the mechanism of acid-base reaction and redox reaction of paper cellulose under the participation of transition metal species. Among them, paper containing iron pigments mainly undergo Fenton oxidative degradation and acid hydrolysis. Correspondingly, the main pathways of paper corrosion by copper-containing pigments are Fehling oxidative degradation and alkaline degradation. This article focuses on the chemical reaction mechanisms of iron-based and copper-based pigments on the corrosion degradation of paper cultural relics, and concludes that the oxidation reaction involving iron and copper ions plays the main character in the accelerated degradation of paper cellulose. For this reason, adding antioxidants—including preventive antioxidants and chain-scission antioxidants—is proposed as a protection strategy to slow down the oxidation reaction of paper-based cultural relics. We focus on the use of complexing agents, such as phytic acid/phytate, ammonium bromide, protein gelatin and others, to coordinate the active iron/copper metal ions and slow down the oxidative degradation reaction. At the same time, some problems in the complexing method are revealed, e.g., phytic acid should be used under acidic condition, pigment discoloration will be caused by using benzotriazole, and some antioxidants may be toxic. Finally, this article proposes a prospect for the space to be explored in mechanism research and protection strategies of paper containing iron-based and copper-based pigments. With regard to mechanism research, the distribution of the free state and the complex state of the transition metal, the conditions for transition metal to initiate the oxidation reaction, and the relationship between the oxidation degradation reaction and the supramolecular structure of cellulose remain to be studied. With regard to protection strategies, the selected protection agents should not only effectively slow down the degradation rate of paper cellulose, but also not cause damage to paper fibers and pigments. This article proposes a more profound understanding of the mechanism of cellulose degradation and evolution caused by transition metal pigments from a chemical point of view and provides guidance and reference for the multi-directional protection of paper cultural relics containing transition metal pigments.

Abstract:The Hall of Mental Cultivation (Yang Xin Dian) is located on West Road, inner court. Yan Xi Tang is on the west side of back palace of Yang Xin Dian. This article is part of the project—“Studies on the paper based artwork in the Yang Xin Dian”—which is a sub-project of the research for the protection of artwork in the Forbidden City. Investigation of the type and distribution of Biaohu paper has been done. Combined with the documentary records, the cross-section of the multilayers, the paper fibers and pigments were analyzed. The investigation and study of the Biaohu paper in Yan Xi Tang, provides a scientific basis for the restoration work.

Abstract:The blue and white Xiu stool unearthed from the Yuyao site in Jingdezhen dates from the mid-fifteenth century and is large in size and special in shape. When unearthed, it was seriously damaged and had significant numbers of missing pieces, making restoration highly difficult. By analyzing the limitations of gypsum as a supplemental material in conventional archaeological restoration, the conservators took advantage of 3D scanning and printing, pioneered the adoption of transparent resins with high-hardness to replace conventional restoration materials, and completed the archaeological restoration of the large blue and white Xiu stool, along with a customized reinforcement device, meeting the needs of subsequent research and exhibition. In this paper, the conservators put forward a practical method involving 3D printing technology for restoring ceramics that are large and irregular in shape.

Abstract:Chengdu Institute of Cultural Relics and Archaeology excavated 60 tombs of the late Warring States period at Feihu Village of Pujiang in 2016, and unearthed a total of 181 bronzes. Among them, from M39, was a bronze belt hook with serious corrosion, on which decorative patterns could not be distinguished. In order to restore its historical, artistic and research value, it is necessary to remove the corrosion on its surface. In this paper, several instruments—X-ray computed radiography system, stereomicroscope, metallographic microscope, scanning electron microscope-energy dispersive spectrometer and X-ray diffractometer—were used to analyze the preservation status, material and corrosion products of the belt hook. The results show that there are exquisite gold and silver decorative patterns distributed on the belt hook, and that gold and silver are used alternately. The substrate with belt hook is poorly preserved and seriously rusted. Gold and silver filaments have fallen off in some areas. The surface is seriously corroded, and cracks exist in some areas. The matrix of the belt hook is cast in lead-tin bronze, with a copper content of 73.0%, a tin content of 11.4% and a lead content of 13.7%. The inlaid gold and silver wire samples are inverted triangles, which were all hot-forged. The gold content of gold wire is 88.8% and the silver content is 11.2%. The silver content of silver wire is 95.8%, and the copper content is 2.4%. The corrosion of belt hook is roughly divided into two layers, the outermost green rust is malachite, and the inner red rust is chalcopyrite. On the basis of scientific understanding of the state of preservation, materials and corrosion products of the belt hook, a technical route of chemical strengthening, mechanical and chemical methods for derusting, chemical strengthening, corrosion inhibition and sealing, and adhesive patching were adopted to protect and repair the belt hook. Paraloid B72 ethyl acetate solution with good permeability and slight color change was selected for small cracks, and a small number of injections were used for reinforcement. Hxtal NYL-1 (Hipstar) two-component epoxy resin with good bonding strength and proper permeability was used for the larger cracks, and a small needle tip was used to infiltrate into the cracks for reinforcement. For the green corrosion on the outer layer, a water solution of disodium EDTA was first used to soften it, and then a mechanical method was used to scrape and remove it. Dark red cuprous oxide corrosion on the inner layer was softened in an aqueous solution of cystein, and then scraped off by a mechanical method. At the same time, in the process of removing rust, the loose gold and silver wires were reinforced with Araldite 2020 two-component epoxy resin. After derusting, ultrapure water was used for deep cleaning to remove reagent residues. An ethanol solution of benzotriazole was used for corrosion inhibition, and an ethyl acetate solution of Paraloid B72 was used for sealing treatment. For bonding and patching, first an ethyl acetate solution of Paraloid B72 was used to pre-reinforce the stubble, and then DG-4 epoxy resin matched with glass fiber cloth and a pin was used for bonding and patching. On the basis of fully understanding the nature of cultural relics by using modern instrumental analysis methods, according to the actual situation of cultural relics, various protection and restoration methods were used in a coordinated way. The corresponding remedial measures were formulated, taking into consideration the shortcomings of each method, so as to achieve the purpose of protection and restoration, and to restore the historical, artistic and research value of cultural relics, and minimize the damage to them.

Abstract:The Stupa Stele in Qiyan Bodhimanda of the Sui Dynasty is among the first batch of national calligraphy art steles. The font of inscription has the calligraphy style of the transition from Wei Bei to Tang Kai. The content of the stele also provides important physical materials for the study of the development of Buddhism and Buddhist temples during the Sui Dynasty and has important artistic value and historical value. Before conservation and restoration, there were many corrosion and crack diseases on the surface of the stele pedestal, and the fracture disease of the stele body was serious, with more than 100 pieces of debris. Compared with the previously reported cases of conservation and restoration of stone cultural relics in the collection, its fracture disease is very typical, and the practice of protection and restoration demonstrates certain significance. The materials, diseases and the properties of bonding materials of the Stupa Stele in Qiyan Bodhimanda were analyzed scientifically using X-ray fluorescence spectrometer (XRF), X-ray diffractometer (XRD), Raman spectrometer, a super depth of field microscopic system, a universal testing machine and other instruments. Combined with 3D digital and finite element simulation analysis, ideas about separate conservation or display of pedestal and body were formed. Combined with the actual needs of storage and exhibition, a special mobile conservation platform was designed and made, which conserved and restored the pedestal and body of stele respectively, restored the original appearance of the stele body, and left the cultural relics in a relatively stable and safe state. The implementation of this conservation and restoration has accumulated experience and provided technical reference for the and conservation restoration of broken stone cultural relics. This paper expands the previous practice of stone stele protection and restoration in the following three aspect:first, was a more comprehensive analysis of the diseases and materials of stone stele, revealing the characteristics of diseases and materials；second, with the help of three-dimensional scanning and finite element analysis technology, a digital simulation and safety evaluation of the restoration of fractured stone stele was carried out; a conservation and restoration implementation scheme involving separation of stele pedestal and stele body and lateral placement of stele body was determined from the perspective of safety and conservation of cultural relics, thus improving the conservation and restoration scientifically；third, combined with the needs for preservation and exhibition, a special mobile conservation platform was designed and produced, which not only results in the safe preservation of the stone stele, but also is conducive to the later display and utilization. Our research focuses on a combination of modern science and technology and traditional restoration, accumulates experience and provides technical reference for the conservation and restoration of fractured stone cultural relic. It has a positive role in promoting the application of finite element analysis in the conservation and restoration of movable cultural relics and improving the science of cultural relic conservation and restoration.

Abstract:Qutan Temple in Qinghai Province is a well preserved official architectural complex of the early Ming Dynasty, which integrates ancient architecture, sculpture, color painting and wall painting. The wall paintings of Qutan Hall are of precious materials representing the early Ming Dynasty wall painting art and Buddhist art archaeology. The existing wall paintings of Qutan hall, which have an area of about 217.5 m², are the classic early Ming Dynasty Tibetan Buddhist wall paintings in the Central Plains. They were analyzed by means of optical microscopy (OM), cross sectional analysis, scanning electron microscopy with energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD), etc. The results of this study show that the wall paintings of Qutan Hall are supported by a brick wall, and that the ground layer is composed of a coarse mud layer and a fine mud layer. The sand content of coarse mud layer is about 60%, while that of fine mud layer is less, about 16%~25%; the total fiber content in plaster is about 3%; the particle size distribution of plaster soil is good, and the particle size is mostly concentrated in the range of 1~100 μm; the plaster contains a small amount of sodium sulfate and sodium chloride; the pigments used in the wall paintings of Qutan Hall are lead, cinnabar, chalcopyrite, parachalcopyrite, stone blue and other mineral pigments; the thickness of the pigment layer is between 20 and 200 μm; the layered application of red lead pigment in Qutan Hall is “lead below, vermilion above”, and shows the phenomenon of lead discoloration. In the wall paintings of Qutan Hall, there is no white ground in Ming Dynasty portion, but there is a white ground from the Qianlong period of the Qing Dynasty. This analysis and research presents information of the Qutan Hall layer structure of wall paintings, the composition of the plaster and the use of pigments, which provides important scientific data for the scientific conservation and further study of the Qutan Hall wall paintings.

Abstract:The Site of Baigongcheng in Cili County has a long history and important archaeological value. A large number of wooden walls were unearthed from the ancient well and a few wooden cultural relics were unearthed from ash pits. This study was carried out in order to comprehend the characteristics and development of the ancient well and materials of daily use in this area, as well as means of wood protection in ancient times. The micro-character of 10 samples from the site was observed by means of optical microscope. It was found that one was Sapindus. mukorossi Gaertn, one, Abies fabri (Mast.) Craib, two were A. acutifolia Hand.-Mazz., two were Toona sinensis A. Juss. and four Machilus pingii Cheng ex Yang. It is preliminarily inferred that the making of well wall was an important work and the wood of well wall was conscientiously used at that time. It also indicates that this area was a mixed coniferous and broad-leaved forest composed mainly of broad-leaved wood that grew in the warm and humid climate in ancient times. The results also provide corresponding information for the protection of wooden relics unearthed in this site.

Abstract:Among the lacquerware unearthed in archaeological excavations, in addition to wooden lacquerware,some are made of leather and fabric, some are made of ramie cloth or silk, and some are made of ramie cloth pasted on a wooden body. Fabric core lacquerware, an object with several layers of fabric pasted to the wooden body, was called Muxiazhu or Xiazhu in the Han Dynasty. A problem worthy of discussion is whether the manufacturing process of Muxiazhu is different from other fabric core lacquer wares and what kind of relationship there is. In order to study the technical features of Muxiazhu in the Han Dynasty, super-depth-of-field video microscopy, X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy and energy dispersive spectrometry (SEM-EDS) were used to research an ear cup of Eastern Han Dynasty, unearthed in Huaibei, Anhui, in October 2011. The microstructure observation showed that there was a clear plain texture between the wood and the plaster layer, and that the thickness of the fabric layer accounts for only 11.4%—far less than the in the usual fabric core ear cup of the same size (the latter is generally more than 50%). The results of compositional analysis showed that the lacquering material was traditional Chinese lacquer, the red paint film was cinnabar, the fabric may be ramie fiber, and that the ash composition contained common materials such as SiO₂, NaAlSi₃O₈ and Ca₈H₂(PO₄)₆H₂O. The above research results show that there was no difference in lacquering materials, pigments and mineral components in ash between “Muxiazhu” lacquer wares and other fabric core lacquer wares, except in the process of making the body. Furthermore, the process of attaching fabric only to one side is not entirely consistent with that of attaching fabric to both sides, as recorded in the literature on the technical features of Muxiazhu lacquer wares. These conclusions provide a new reference for the study of fabric core lacquer wares. This paper reveals the manufacturing technology of Muxiazhu in the Han Dynasty from the aspects of materials and painting process for the first time. In fact, the development of body technology witnessed the evolution of lacquerware from thick-wood to thin-wood and then to fabric cores. It can be found from archaeological lacquer wares, such as lacquer Zhi and lacquer Zun, that their structure is not firm, because the joints at both ends were only bonded by adhesive. In order to prevent lacquer wares from cracking, painters pasted fabric on the wooden body. The kind of technique to enhance the firmness of the body with the help of ramie fiber is called Muxiazhu. Although it remains to be further discussed whether Muxiazhu technology directly promoted fabric core lacquerware, it should at least be seen from the law of the development of traditional handicraft technology that the former gave some inspiration to the latter. This kind of technique is still widely used in modern furniture production.

Abstract:The extraction and transport of complex and fragile cultural relics or fossils is the most encountered technical problem in archaeological and paleontological excavation sites. Gypsum is one of the mostly commonly used consolidation materials on-site and plays an important role in the extraction and transportation of complex and fragile cultural heritage objects or fossils. However, gypsum contains a certain amount of soluble salts, and a large amount of water is always required during its heavily exothermic application process. All these are potentially harmful to cultural relics or fossils. Furthermore, gypsum is also very difficult to remove completely. In recent years, volatile temporary consolidation materials such as menthol and cyclododecane have attracted great attention and are more and more widely used in excavation sites. Their biggest advantage is that the material can be easily removed by sublimation without leaving a residue, and thus will not affect the subsequent archaeological research and protection work. However, the mechanical strength of organic compounds is normally weak, so that they are not suitable for extraction of large and heavy cultural relics or fossils. In view of the demand for the extraction and transport of complex, fragile, large, and heavy cultural relics or fossils at excavation sites, we propose a novel technical approach of composite application of menthol and gypsum. In this paper, the compatibility of gypsum and the organic small molecule, menthol, is examined. The laboratory results show that menthol can not only realize effective consolidation, but also can quickly form a dense hydrophobic isolation layer on the sample surface, which can effectively prevent the entry of water and soluble salts during the gypsum applying process. The heat generated by gypsum conversion will not affect the hydrophobic function of the menthol layer. The experimental results show that menthol and gypsum complement one another, and are expected to meet the extraction and transport needs of large and heavy cultural relics or fossils at excavation sites. Taking the consolidation and extraction of pterosaur fossils in Hami, Xinjiang as an example, a 20 kg fossil sample was consolidated and extracted on site. The results confirm that the gypsum and menthol composite technology can well consolidate and extract large and heavy samples while avoiding the damage of water and soluble salts to the fossils. Due to the existence of the menthol isolation layer, the gypsum can be removed completely. The overall outcome is satisfactory.

Abstract:The sterilization and protection of painted cultural heritages is an important method to extend their artistic value. This paper briefly explains the damage effects in terms of five factors—cultural heritage-related materials, temperature, humidity, air pollutants and microorganisms—on painted cultural heritage objects, and focuses on the importance of microbial sterilization in the preservation of painted cultural heritage objects. The application and development of chemical, physical and compound sterilization methods in sterilization of painted cultural heritages are summarized, and the advantages and disadvantages of each method are summarized. Chemical methods are the most mature, but most of them have a bad impact on the environment. Physical methods and complex methods are more suitable for green development, but they are constrained by economy, specialization and immature market size. In the future, green and nondestructive methods will become the premise of sterilization of painted cultural heritage objects, and compound methods will become the development trend of future research in this area.