Abstract:Fengguo Temple is located in the northeast of Yixian County, Jinzhou City, Liaoning Province. According to an inscription inside the temple, construction of the temple began in 1 020 AD, the ninth year of Kaitai during the Liao Dynasty. The main hall, Daxiong Hall, is so far the largest single wooden structure of all Liao Buddhist architecture. Daxiong Hall has a total of 20 mural paintings of the Yuan Dynasty with a total area of 466.7 square meters. These paintings are outstanding representatives of the fresco art of the Yuan Dynasty and boast high historical and artistic value. Due to an old age, several repairs and an unstable conservation environment, diseases, especially crack disease, have been very prominent, not only affecting the integrity and beauty of the mural paintings, but also destroying their safety and stability. For these reasons we selected the mural paintings of Fengguo Temple of the Yuan Dynasty as research objects. First of all, we determined the distribution of cracks, judged their types and summarized their characteristics. Then we evaluated the causes of cracks of the mural paintings with reference to the methods of analysis used for studying the causes of building wall cracks. Finally, we systematically and comprehensively summarized the cause of crack disease in the mural paintings in terms of crack attributes, causes and processes. From this study, it is shown that the building and foundation structures are stable that there is no uneven settlement. Cracks in the murals are due to temperature changes. The deformation stress caused by curing shrinkage and temperature shrinkage of epoxy resin is restrained in brick walls, which will be released in the earthen layer. This stress will cause deformation of the earthen layer and if the residual stress is still greater than the ultimate strength of the earth layer, the cracks will be earth layer.  In this study, we developed a new research system suitable for crack diseases of mural paintings by a combination of practical investigation and the analysis of influencing factors. This research system can not only provide a theoretical basis for the further protection of murals, but also, to a certain extent, make up for the gap in this field, making the disease analysis process of murals more scientific and logical. It also provides a reference for the analysis of crack disease in other areas.

Abstract:Most cultural relic architecture is in an outdoor environment, which causes ancient grey brick relics to be faced with serious environmental erosion and weathering problems. As a result, brick cultural relic architecture suffers physical and chemical weathering due to freeze-thaw cycles. In this study, we took grey bricks from ancient buildings as research objects to assess the effects of freeze-thaw cycle times on mass, void ratio and compressive strength. The bricks were subjected to 0,15, 30,45, 60 and 75 freeze-thaw cycles, and the microstructural changes in the bricks were observed using transmission electron microscopy (TEM). It was seen that, with an increase of freeze-thaw cycles, the mass loss ratio and void ratio increase while the compressive strength decreases. Micro-damage to the bricks was observed by TEM during the process of freezing and thawing,especially after the test with 75 cycle times. In addition, the chemical composition of the bricks was tested using X-ray photoelectron spectrometry (XPS), which showed that hydrolysis of soluble salt (e.g. carbonate) crystals is the main cause of the microstructural damage in chemically weathered bricks.

Abstract:Iron sulfide is a common and harmful insoluble salt in unearthed cultural relics. Therefore, the feasibility of removing ferrous sulfide using 1,2-dimethyl-3-hydroxy-4-pyridone was studied under mild conditions. On the basis of this experimental study, the molecular structures of different hydroxypyridone derivatives were analyzed at B3LYP/6-31G* level by Gaussian 09 software. The results show that N-(α-aminobutyryl-3-hydroxy-4-pyridone, a mono-functional group hydroxypyridone, may be a more effective chelating agent than 1,2-dimethyl-3-hydroxy-4-pyridone.

Abstract:Polyvinyl acetate (PVAc) emulsion is a common conservation material used for conservation of painted cultural relics. In this study, the thermal stability, structure, morphology and particle size of PVAc emulsion were characterized and analyzed using thermogravimetric-differential thermal (TG-DTG) analyzer, Fourier transform infrared (FT-IR) spectrometer, X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and laser particle size analyzer. The relationship between the concentration of PVAc emulsion and its viscosity, surface tension, pH value and conductivity were investigated using a viscometer, surface tension meter, pH meter and conductivity meter, respectively. The stability of the PVAc emulsion was examined by freezing and thawing test, room temperature-high temperature placement, and centrifugal separation. In addition, to further verify its properties, the PVAc emulsion was used for the restoration of flaking and disrupted murals. The results show that 1) the particle size of the PVAc emulsion was bimodal, the average particle size of small particles was 380 nm and the average particle size of large particles was 5.85 μm; 2) the final mass residue of the film was 1.54%, the exothermic peak appeared at 335 ℃, and the emulsion was of amorphous structure; 3) with the increase of the PVAc emulsion concentration, the surface tension decreased and the relative viscosity increased； 4) PVAc emulsion is stratified by freeze-thaw, centrifugal separation and room temperature-high temperature placement. After repairing the flaking and disrupting murals, the samples are cycled for 20 times and aged for 12 times, respectively. It was found that the repairing murals were again flaking and disrupting. All results suggested that the PVAc emulsion used in this work has poor stability and anti-aging performance. Therefore, during the restoration of painted cultural relics, the influence of PVAc type, PVAc concentration, and environmental factors on its performance should be carefully selected to achieve the best effect in use.

Abstract:Cultural relics are reminders of the precious cultural heritage of mankind. Microorganisms, such as fungi, can cause severe destruction to items in museums. The impact of fungal activities on the deterioration of cultural relics is a serious problem and thus the preservation of cultural relics is a challenging task. Physical treatments such as ultraviolet radiation and γ-radiation can induce deterioration of microorganisms, but they can also affect most heritage materials. Physical treatments have short-term effects, and the surfaces of cultural relics are readily recolonized. Furthmore, many chemical compounds (biocides) are not used for antifungal because of their possible harm to human body and their fungal resistance.In the light of these problems, there is a growing need to develop effective alternatives. The search for natural and environmentally-friendly alternatives, which show negligible toxicity to human, was a main goal for the present studies. As extracts of aromatic plants, essential oils (EOs) have many advantages:1) having a wide range of antifungal efficacy; 2) being easy to use and extract from a wide variety of sources; 3) having strong volatility and being environmentally-friendly. Botanical fungicides based on essential oils are undoubtedly popular to prevent fungal growth and control fungal decay on culture relics. Three frequently-occurring airborne fungal species from exhibition halls in Anthropology Museum of Guangxi were isolated, purified and identified. The antifungal activities of basil, myrcia and Litsea cubeba essential oils were examined against the three fungal species and also compared to determine the potential uses of plant essential oils as novel antifungal agents. Isolation, morphological identification and molecular identification were carried out for highly frequent species. With a drilling method and according to minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), the essential oils were evaluated for their efficacy in reducing the fungi isolated in museum air. The anti-fungal activities of these essential oils were also tested on paper. After uniform spraying of plant essential oils on the surface of paper, the paper was incubated in a constant temperature and humidity incubator for 28 days. Then, the mildewed area on the surface of paper samples in the treatment group and the control group were observed. In addition, the major components of these essential oils were analyzed and identified using gas chromatography-mass spectrometry (GC/MS).  The three fungi species were identified as Penicillium oxalicum (the accession number MK811098), Penicillium herquei (the accession number MK811099) and Aspergillus aculeatus (the accession number MK811100). They were susceptible to the tested essential oils. According to antifungal activity, MIC and MBC of the tested essential oils with different concentrations, the most efficient one was myrcia oil (MBC ranging from 700~900 μL/L) followed by basil oil (MBC ranging from 700~1 000 μL/L) and Litsea cubeba oil (MBC ranging from 700~800 μL/L). The mildewed areas on the paper of the treatment group were all smaller than those of the control group, which shows that all of tested essential oils had mildew-proof activities on paper. These results suggest that basil, myrcia and Litsea cubeba oils have potential as natural antifungal agents against fungi. The antifungal activity order of the three essential oils was:myrcia oil>basil oil>Litsea cubeba oil. Geraniol (57%) and 2,6-Octadien-1-ol, 3,7-dimethyl-, (Z)-(38.31%) were the major active components of myrcia oil, eugenol (83.14%) and hexylene glycol (16.15%) were the major active components of basil oil, and citral (36.01%), 2,6-Octadienal,3,7-dimethyl-,(Z)-(29.71%) and D-Limonene1(6.67%) were the major active components of Litsea cubeba. The inhibitory effects of plant essential oils on moulds were studied by laboratory methods, and also verified by comparing the antifungal effects on paper. The results show that plant essential oils had significant antifungal effects. This study has indicated that, as a kind of purified agent against airborne moulds, plant essential oils have good prospects as antifungal agents for the museum storage and exhibition environment.

Abstract:The unique texture and luster of jet make it one of the important materials for making ornaments and handicrafts, and has been used in China since the middle Neolithic Age. At present, the identification of jet artifacts is mainly based on appearance morphology, scratch color and destructive petrologic methods, but few non- or micro-destructive scientific investigations have been conducted. In this study, the non- and micro-destructive scientific analyses of a black bead unearthed in a Western Han tomb from Shengjindian Cemetery in Turpan, Xinjiang was carried out using gas chromatography-mass spectrometry (GC-MS), infrared spectrometry and synchrotron radiation micro-computation tomography (SR-μCT). The results show that the bead is made of jet with a uniform structure, and that double-sided drilling technology, polishing and trimming were utilized in its production. Jet artifacts gradually appeared in the tombs of low-rank people since the Western Han Dynasty. This phenomenon of consumption popularization might be related to the first large-scale exploitation of coal in the Han Dynasty. Moreover, since the Han Dynasty, jet artifacts have sporadically appeared in Xinjiang, suggesting that the utilization of jet artifacts in Xinjiang was probably influenced by Han culture.

Abstract:The two bronze chariots excavated in 1980 from the west side of Emperor Qinshihuang’s Mausoleum, each with a weight of more than 1 ton, are the largest bronzes of Bronze Age in China. Featuring complex structures, complete shape and construction, as well as exquisite craftsmanship, the bronze chariots not only represent the highest level of handicraft production of that period, but also provide an important entry point to understanding the chariot system, production organization, metal craft and other aspects of the Qin Dynasty. According to records, there were strict requirements for all kinds of handicrafts made during the Qin Dynasty. Preliminary studies also showed that the bronze chariots were half the size of real Qin chariots. This production ratio shows a strict requirement for chariot shape during Qin Dynasty production, which has made scholars consider the precision of components of the bronze chariots. It is worth studying and analyzing systematically whether components of the same kinds of bronze chariots were produced according to uniform specifications and the standard level of production during the Qin period. In this paper, standard deviation analysis of the dimensions of components, such as bronze horses and silver parts, of the same kinds of the bronze chariots, and numerical analysis of the compositions of bronze components unearthed and detected in a few pieces, are used to evaluate the level of standardization in the production of bronze chariots. Standardization of component size (bronze horses) For example, bronze horses are the largest casting components of the bronze chariots. The heights of the horses range between 89.8 cm and 93.2 cm—on average is 91.7 cm—with a standard deviation is 0.91 cm; the ratio of the standard deviation to the average height is only 0.99%. The standard deviation of the body lengths of the bronze horse is only 1.9 cm, with a ratio of the standard deviation to average value of 1.7%. Each bronze horse has a large cavity. In the production process, craftsmen utilized many crafts, such as casting and welding, etc. Although the production process is complex, the heights and body lengths of the eight bronze horses still maintain a high degree of consistency. Standardization of bronze component composition At present, there is much data on the composition of bronze components of the bronze chariots, covering several categories of components from different positions and with various functions on the chariots. For example, in the No.1 chariot the copper content of the underframe is 88.11%, the copper content of the umbrella is 88.93%, the copper content of the solder used in high-temperature brazing is 88.26%, and the copper content of the bronze wire is 88.04%. These components have completely different positions, mechanical property requirements and appearance, but their copper and tin contents are almost the same. However, there are some differences in the copper content of the components from the same position or with the same function. For example, the copper content of the front leg of the left horse of the No.1 chariot is 83.02%, while the copper content of the left front leg of another horse on the No.1 chariot is 87.26%. These data show that there is no regular and obvious difference in the contents of copper and tin between different components, and that the contents of copper and tin are distributed stably within a range. This research shows that the ratios of the standard deviations to the average values of the sizes of the same kinds of components in the bronze chariots are within 2%, and that the standard deviations of the copper content in bronze components are within 3%; thus the compositions of bronze components are highly unified. The bronze components are all copper-tin bronze and contain approximately 90% copper and 10% tin, no matter what the shape or the position of component. The high level of standardization in size and metal composition of bronze chariots indicates that there exists a highly standardized social production since the unification of six states by Emperor Qinshihuang.

Abstract:In this study, we scientifically examined two bronze tools unearthed from Huikeng Site of the Eastern Zhou Dynasty at Laohudong, Xiaoshan, in Hangzhou. Observation of the metallographic structure in cross section revealed of the two bronze tools each presents a cast structure from the edge to the back; forging marks are not found. In these tools most of the α-phases have been completely corroded, with only dendritic corrosion products left; some α+δ phases have small residues. Also, a piece of free copper and an incompletely corroded metal particle were found in the H10:1 bronze tool. A nearly equal size hole was observed near the free copper, which is considered to be a Kirkendall phenomenon due to different diffusion rates of Cu and Sn. Analysis of the incompletely corroded metal particle using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), revealed that the two bronze tools are made of an alloy high in Sn and Pb. A high content of Sn can increase the δ-phase, which is beneficial to enhancing the hardness of the tool base; a high Pb content could easily fill the shrinkage hole left by solidification of the Cu-Sn alloy, which is beneficial to maintaining the strength of the tool base. This shows that the ancestors of Laohudong had fully realized the influence of alloying on metal tools. Furthermore, according to historical data, Laohudong Site was located in the Wu and Yue States during the Eastern Zhou Dynasty. The Yue bronze cutlery unearthed from Yushan Site in Zhenhai and the Wu bronze wares unearthed from southern Jiangsu of the same period, also show high Sn contents. Therefore, Wu and Yue States had a high level of metallurgy; Laohudong Site adds more strong evidence for this.  The corrosion state of other areas is very serious except for the free copper and incomplete corrosion metal particles found in Sample H10:1. Although there is δ-phase residue, it cannot be said that the α-phase is the preferential corrosion phase, because the metallographic observation provides only the final residual result; the initial state of corrosion cannot be determined. For this reason, this study uses a new method, namely interpretation of the order of metallographic corrosion from the average electrode potential according to Gibbs free energy theory, which is based on the electrochemical reaction model of bronze base and the standard electrode potential of the materials involved in the reaction. The α-phase is a Cu/Sn solid solution and its average electrode potential varies with the ratio of Cu/Sn in the solid solution. The δ-phase consists of intermetallic compounds, so the average electrode potential of α-phase and α+δ phase are not fixed values, and are related to the casting composition, segregation state , burial environment corrosion state, etc. The phase with a lower electrode potential is used as anode for corrosion reaction. In theory, Pb is not miscible with Cu and Sn and its electrode potential is the lowest, so its corrosion reaction takes precedence. Then α is the Cu-rich phase and δ is the Sn-rich phase. Because ’ECu°＞’ESn°, δ phase or α+δ phase should be used as anode for reaction. But in reality, due to the influence of various factors or as the reaction proceeds, the ’ECu° and ’ESn° are likely to be interchanged and the direction of reaction is affected. Therefore, the preferential corrosion phase can’t be generally identified from the corrosion residual state of metallographic structure, and the average electrode potential is a way to predict the electrochemical corrosion direction. This method can be applied in the field of cultural relic conservation and restoration as well. Especially for the restoration of metal objects, it can be considered to use those with lower electrode potentials as restoration materials, so as to achieve the purpose of protecting the metal cultural relic base in the electrochemical corrosion environment.

Abstract:Lead-glazed pottery is an important category of ancient ceramics in China. The surface of the artifacts is prone to corrosion phenomena such as “silvery glaze” and “iridescent lamellae”. We analyzed seven pottery samples from Song Cizao kiln in Quanzhou, Fujian, using stereomicroscopy, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) and Raman spectrometry, aiming to explain the long-term transformation and alteration deposition of lead glaze in the buried environment. The results show that the main components of the glaze layer are PbO and SiO₂, with Cu and Fe used as coloring elements. The pottery body is made of non-calcareous clay, and it is speculated that the white intermediate layer at the junction of the glaze and body is K-Pb feldspar crystals. The “iridescent” phenomenon on the glaze presents multi-layered structure, which is mainly caused by the erosion of water. In the course of this erosion, some preferential components (mainly alkali metal, alkaline-earth metal and lead oxide, etc.) in the glass phase are transferred into the environmental medium. This occurs by ion-exchange reactions between H⁺ and Pb²⁺, Cu²⁺, K⁺ and Rⁿ⁺, etc. in the glaze to form an alkali-deficient silica-rich layer [silica gel:Si(OH)₄·n(H₂O)]. Due to the reaction of leached ions in the burial environment, the corrosion products contain lead carbonate, calcium carbonate and lead phosphate crystalline phases.

Abstract:Ancient books are an important carrier of ancient Chinese cultural information. Benefiting from the prosperity of engraving and the printing industry in the Ming and Qing Dynasties, a large number of Ming and Qing books have been preserved; these are of great value to the study of ancient social systems and the degree of development of civilization. Handmade paper, as an important material for making ancient books, is of great significance for the conservation and restoration of ancient books. At present, research on Ming and Qing editions mainly focuses on textual research, while the paper of ancient books draws little attention and lacks relevant research on its production and development.  In order to study the raw materials and the process of production of paper of ancient Ming and Qing books in Jingzhou, we selected seriously damaged books in Jingzhou Museum for analysis and made comparison with modern handmade paper. The analyses include fiber identification, filler and coating analysis and basis weight and thickness analysis of these samples. The results show that the raw materials of the paper in these books are all bamboo pulp, that its fillers are mainly composed of chalk or talcum powder, and that its coating minerals contain kaolin. According to a literature , the paper industry in Jingzhou has been relatively little changed since ancient times. The printing industry was established in the Five Dynasties and Ten Kingdoms Period. In the Ming and Qing Dynasties, Jingzhou became one of the main sites of paper mills in the country. Therefore, given the consistency of raw materials and processes in these sets of ancient book samples, as well as the local capacity to produce printed paper, it is speculated that the books were most likely produced locally. In the selection of paper for restoration, following the principle of “repairing the old as the old”, the first choice is bamboo paper. Because of the physicochemical properties and production status of handmade bamboo paper in China, it was decided to use Jiajiang paper from Sichuan. This paper expands previous studies in two aspects:1) it provides a reference for the study of the paper used in ancient books and the papermaking situation during the Ming and Qing Dynasties in Jingzhou, filling a research gap in this field in this region; 2) combined with the related literature of ancient papermaking technology, it compares the raw materials and techniques used for the paper of ancient books in the Ming and Qing Dynasties with modern handmade bamboo paper, which has certain reference value for the study of the maturity of ancient papermaking techniques. This article represents a beneficial exploration of papermaking in three different times—the Ming Dynasty, the Qing Dynasty and modern times—and provides a strong scientific support for the conservation and restoration of the ancient books in Jingzhou Museum. It provides advice for local agencies involved in buying or making repair paper for ancient books, and also provides reliable basis for the supplementation of cultural relic documents.

Abstract:The Pillar Testament of Songtsen Gampo, a 15th century Tibetan manuscript, was blocked severely due to water damage before being collected by Tibet Museum. During 2017 to 2019, the National Museum of China was commissioned to carry out conservation and relevant research. The manuscript is assembled in a pothi form, which is a typical bookbinding form in Tibet, with loose oblong leaves and a protective wooden board (the back board is missing). The first and last leaves serve as the inner covers with multi-leaf structures fixed by paper clips and exquisite hand-painted illustrations. The leaves of the manuscript are beige Tibetan paper, made from 100% Stellera fibers of Thymelaeaceae family according to the dyeing reaction and morphological characteristics. Two or three pieces of paper were pasted together to form one flat and smooth leaf. A thick coating on the surface was observed by microscope, indicating that the leaves had been coated and polished. Blocking was the major damage. Except the first three leaves, the manuscript was blocked into four pieces with various thickness from 0.4 to 1.8 cm. Mould was distributed mostly on the margins of the leaves, presented as bright yellow halos and dark brown spots, which were identified as Cytospora chrysosperma based on morphological data and molecular sequence. In addition, there were also water stains, fragility, losses and other damages, increasingly severe from front to back and from left to right. It is inferred that the water invasion started from the back and the right side of the manuscript. The restoration procedures included separating, cleaning, filling, reinforcing, moistening and flattening. The moisture permeable material SYMPATEX was used for moistening before separating, and the moistening time and separating strategies were adjusted according to different blocking conditions. Finally, 162 leaves were separated. To remove the dust, mould, and deposits on the surface of leaves, a vacuum cleaner, a scalpel and other tools were applied for preliminary cleaning, and microfiber cloth was used for further cleaning after local testing, which is especially useful for fine dust and mould embedded among the fibers. To repair the losses and fragility on the margins of the leaves, a kind of handmade Tibetan paper, named Jindong Paper made in Nang County, Tibet, was selected. The paper is much thicker than commonly-used repair paper and has different textures on both sides, so the wet paper was balled and stretched after the application of pigments to make the dyeing more uniform and inartificial. The missing parts of the leaves were filled and overlapped both on the front and back sides. Paste was applied onto the filling paper, which would not be put onto the missing areas until it became half-dry to avoid tideline. The vulnerable areas were reinforced with a thin layer separated from Jindong paper. Before flattening, SYMPATEX was also used for moistening. Considering the different shrinkage properties of repair paper and original leaves, the filling areas were moistened locally first and then the whole leaf was put into the SYMPATEX damp pack to moisten. The restoration has achieved satisfactory results. During this work—from moistening, separating, cleaning, filling, reinforcing to flattening—considering the distinctive characteristics of the Tibetan manuscript, many delicate designs and adjustments were made, based on restoration technologies for general paper-based objects. Some new thoughts could thus be provided for the restoration of similar objects.

Abstract:Along with the continuous development of China’s economy and society, the concept of preventive conservation of cultural relics has been deeply understood. The protection of cultural heritage in China has gradually entered a prosperous stage, and research on the preservation environment of cultural relics has also made remarkable progress. According to the 13th Five-Year Plan for the Development of National Cultural Relics, the protection of cultural relics should shift from “placing emphasis on the protection of cultural relics themselves” to “paying equal attention to the entire environment, including protection among cultural relics themselves, their surrounding environment and the cultural ecology”, in order to ensure the safety of cultural relics. At present, many domestic museums and other cultural institutions have successively built environmental monitoring systems for the preservation of cultural relics based on wireless sensor networks, which basically realized the function of real-time monitoring and information management for the cultural relic preservation environment. In November 2016, the first regional center monitoring platform of museum environment in China has been established in Sichuan Province. This platform has an integrated network of 12 museum monitoring stations after operations and practices of more than two years. However, the influence of equipment faults and software platform construction led to a low data utilization, and some management functions, such as risk assessment, forecasting and warning and preventive control, etc, cannot be realized, which constrains further development of the regional center, and then affects the construction of the three-level linkage monitoring system for preventive conservation. In this paper, six monitoring stations in the Sichuan Regional Center with monitoring data of at least half a year in 2018 were selected. Firstly, the application status of hardware equipment and software platform, common fault forms and fault causes about monitoring stations are analyzed in detail by statistical analysis, and the fault rates of different pieces of monitoring equipment are calculated. In view of the problems discovered by analysis, take the experimental exploration as example and in combination with the practical application requirements of preventive conservation for cultural relics, some corresponding technical measures and management measures are put forward. The results indicate that the main fault phenomena are transmission and data anomalies among the common faults of the monitoring platform. The fault rates of other types of monitoring terminals are high except for temperature and humidity monitoring terminals. Moreover, the construction of software platform is not perfect enough, either, which limits the application value of monitoring data. The construction of regional centers for the preservation environment of cultural relics is an emerging thing in the heritage and museum industry, and there is no relevant experience of operational management for reference. This paper analyzes the problems of hardware equipment and software platform encountered in environmental monitoring for the preservation of cultural relics since the establishment and running of the monitoring platform of Sichuan Regional Center, to preliminarily explore corresponding improvement measures. On one hand, this is conducive to reducing the incidence of faults and avoiding the accumulation of invalid data. Gathering and deep mining of massive amounts of data provide a basis for the regulation and governance of the preservation environment, to minimize the damage to cultural relics caused by environmental factors as much as possible. On the other hand, this provides some guidance and reference for other museums and cultural institutions where regional center platforms are being or will be built. It also provides support for the setting of relevant professional standards in the next step, and even for the access to the platform of “National Monitoring Center for Preservation Environment of Cultural Relics” in the future, in order to achieve seamless connection and unified management among different environmental monitoring systems.

Abstract:Pigment layer crack is a common disease type found in oil paintings. Severe cracks can affect the visual effects. The aim of taking conservation measures for oil paintings is to alleviate deterioration, extend life expectancy and avoid devaluation of oil paintings due to improper restoration. Based on the analytical results from Fourier transform infrared (FTIR) and portable X-ray fluorescence (pXRF) spectrometry, it was preliminarily determined that the cause of the crack generation was related to materials, techniques and mechanical forces. Long-term temperature and humidity fluctuation is an important factor for the formation of aging cracks. After a comparison of two common crack reinforcement methods, it was concluded that colored wax would change the gloss and texture of original paintings, and that animal glue-adjusted calcium carbonate is more suitable as a crack filling material. Observation of the preservation state of oil paintings after restoration shows that the restored pigment layer still has a risk of continued deterioration. Only by the maintenance of the relative stability of the preservation environment can the restoration cycle be extended.

Abstract:Coating is important for the conservation of iron relics. This study selected ordinary carbon steel plates, which had chemical compositions similar to those of Ling Zhao Xuan. All the samples (smooth, sandblasted and rusted) were artificially aged under different conditions. The results show that:establishing an evaluation system in the field of cultural heritage conservation for the elimination of corrosion layers or the removal of chlorides. However, this system is also a valuable tool for assessing the anti-corrosive efficiency of protective coatings； In the second stage, the fluorosilicone rubber (the samples were coated with silicone and then coated with fluorosilicone rubber)(GB) coating is better than fluorosilicone rubber (the samples were scrubbed with tannic acid and then coated with fluorosilicone) (GC) and fluorine rubber (GA), but the GB coating needs to be tested in the next stage. It is certainly worth differentiating the surface condition of the samples. Three surfaces condition of the samples results vary widely, the smooth surface can objectively present the evaluation results, and the rust surface is closed to the iron relics.

Abstract:Identification of ancient textile fibers is of great significance for the conservation of textile relics. Traditional fiber identification methods require sampling and slicing cultural relics for observation under an optical microscope or a scanning electron microscope. The fiber types are identified through the morphology of fiber cross section or fiber surface. However, these methods cause damage to cultural relics and are complicated. In recent years, near infrared spectroscopy has been applied to qualitative analysis of textile fibers and quantitative analysis of blended fabrics in the textile industry. In particular, near-infrared fiber optic reflectance spectroscopy (NIR-FORS) has the advantages of being nondestructive, portable and free of the volume limit of the substance to be measured, which is expected to be applied to the nondestructive detection of ancient textile fibers. In our study, cotton, linen, silk, wool, polyester and 16 kinds of natural dyes were selected as study objects. The characteristic absorption peak positions of the near-infrared spectra of five dyed fibers were analyzed using a portable NIR-FORS. The amide A/Ⅱ and amide B/Ⅱ absorption bands of silk are at 2 058 nm (4 859 cm-1) and 2 200 nm (4 545 cm-1), respectively, and the amide A/Ⅱ and amide B/Ⅱ absorption bands of wool are at 2 052 nm (4 873 cm-1) and 2 177 nm (4 593 cm-1), respectively. The position of these two absorption bands can be used as a criterion for distinguishing wool from silk. The characteristic absorption of polyester at 1 660 nm (6 024 cm-1) originates from the benzene ring in the polyester, which can be used as a basis for the determination of polyester fiber. The near-infrared spectra of cotton and linen are very close (both are cellulosic) and cannot be directly identified. The Thermo scientific TQ Analyst 8 analysis software (discriminant analysis) was used to establish a discriminant model (the number of standard sample sets were cotton 70, linen 100, silk 60, wool 67 polyester 70, and the verified sets were cotton 20, linen 20, silk 20, wool 20, polyester 20, with bands of 1 600~1 800 nm and 2 000~2100 nm). The distance between the unknown material and the center of each category is calculated by Mahalanobis distance, allowing the similarity between the unknown sample and the standard cotton and linen samples to be judged. The results show that the model’s Performance Index is 95.694, indicating that the model’s prediction is accurate. It can quickly identify cotton and linen. In addition, dyes and mordants have few effects on the characteristic absorption peaks of fibers, and do not affect the judgment results in practical applications.  This method was applied to the identification of fibers from four Qing Dynasty textile relics, and resulted in a good spectral comparison. It was shown that the portable NIR-FORS has the following advantages in the identification of ancient textile fibers:1) no need for sampling, non-destructive and the volume of cultural relics is not limited; 2) steps are simple and test results can be obtained quickly; 3) the characteristic absorption band of the fiber is not affected by the type of dye and mordant; 4) finer fiber identification can be obtained on dyed textiles. This method will help conservation workers to rapidly analyze large quantities of cultural relic fibers and to pursue investigations, and for archaeological workers to conduct in situ detection.