Abstract:The Dayingzi Smelting Site, located at N 43°10′06.6″, E 118°26′45.1″ in Inner Mongolia, is divided into eastern and western areas. The accelerator mass spectrometry (AMS) dating of the eastern area suggests that smelting activity began from 1 000 BC at the latest, while that of the western area began about 200 years later. Furthermore, according to the lead isotope and trace element analyses and other methods, we found that the entire site used polymetallic ore from the famous Dajing Mining Site (60 km north of the Dayingzi Site) to smelt Cu-Sn-As alloy. The AMS dating results give, so far, the earliest date of the Upper Xiajiadian culture and also provide new scientific evidence for the research on the evolution of Bronze Age archaeological cultures in Liaoxi Region.

Abstract:Some metal ornaments covered with patterned gold leaves were excavated from two Chu tombs (dating back to the late Spring and Autumn period), namely M12 in Zhaoxiang and M5 in Caojiagang in Dangyang, Hubei province. Compared with other analogous artifacts, the large number, diverse characteristics and exquisite craftsmanship of these gold leaves suggest significant historical value and high status, which will contribute to the understanding of the burial customs of the Chu State during the Eastern Zhou period. In our research, we applied a variety of scientific methods, including scanning electronic microscopy (SEM), X-ray fluorescence spectrometry (XRF), three-dimensional video microscopy, laser confocal microscopy, colorimetry, vancometer measurement and gas chromatography with mass spectrometry (GC-MS) to study 194 gold leaf samples in terms of their elemental content, thickness, color, glossiness, patterns and manufacturing techniques. The results indicate that 1) the gold leaves are Au-Ag alloys which contains 82%～95% gold and 5%～18% silver; 2) the thickness varies from 7 to 35 μm. Compared with other gold leaves unearthed from pre-Qin tombs, these gold leaves are the thinnest and have relatively higher gold contents. In addition, their surfaces are much brighter and have abundant sculptural types, as well as more elaborate ornamentation. Combining the scientific data obtained, we also evaluated the superb manufacturing techniques of the Chu State based on the technical characteristics of gold leaves. The smelting technology and manufacturing process used for these gold leaves are discussed in this paper.

Abstract:The gilded lacquer gauze is a unique interior architectural decoration found on the first floor of Fu Wang Ge which is located in the Qianlong Garden of the Forbidden City. In order to study its micro-stratigraphy and the organic/inorganic materials present in each paint layer, we applied a variety of analytical methods including cross-sectional microscopy, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), micro-Fourier transform infrared (mFTIR) spectrometry, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), gas chromatography/mass spectrometry (GC/MS), and high performance liquid chromatography-diode array detection-mass spectrometry (HPLC-DAD-MS). A combined interpretation of the data allowed us to re-establish the techniques of lacquer gauze, and also provided sound scientific directions for its conservation.

Abstract:The technology of amalgamation and gilding in China originated before the Warring States period and greatly improved the ornamental value and corrosion resistance of bronzes, thus bringing a new atmosphere to the bronze culture of the Eastern Zhou Dynasty. Due to long-time underground burial, gilt bronze wares are often found, after excavation, covered with a hard layer of soil rust, which seriously affects their appearance and subsequent stabilization treatments. At present, methods of removing rust from gilt bronze wares include wet chemical, laser ablation and mechanical methods, all of which have some problems. Based on corrosion characteristics of gilt bronzes, we created a new method for removal of rust based on a composite hydrogel system, where acrylic acid and polyvinyl alcohol act as gelling agents, and solutions of weakly acidic formic acid and cysteine are used for washing. Implementation of this method shows that it can remove the rust (i.e, cuprite, malachite and azurite) from the gilding layer efficiently without damaging the surfaces of cultural relics. This method is suitable for cleaning complicated surfaces, in that it can reduce corrosion damage and also conforms to the principle and requirement of “minimal intervention” and “not changing appearance” for cultural relic conservation.

Abstract:To improve operating times, conservation effects and environmental protection when using dehydration for conservation of waterlogged wooden cultural relics, we studied a new method, namely, polymerization-freeze drying with water-soluble monomers such as acrylamide (AM) and N-Vinyl-2-pyrrolidone (NVP). The waterlogged wood samples treated were from the Tianluoshan, Hemudu and Maoshan Liangzhu Culture Sites. The monomers at different concentrations were polymerized in water. The optimal polymerization systems were then selected on the basis of volume change rate after polymerization and freezing. Five polymerization systems with change rates controlled within ±5% were finally chosen for research on dehydration conservation. When the total concentrations of AM and NVP in monomer polymerization-freeze drying system were equal to or less than 7.5%, the size change rates of the samples could be controlled within ±5%.

Abstract:In addition to usual concerns about mold-induced deterioration, the potential impacts of bacteria in cultural relic preservation and exhibition environments have received more and more attention. Removal or reduction of airborne microorganisms inside museum exhibition halls would be helpful to preserve cultural relics. In our study, five plant-derived extracts were used as purifying agents to fumigate, in the plate, airborne microorganisms sampled from a museum exhibition hall. In order to evaluate the effects of inhibition on airborne microorganisms, the bacteria were quantified by pure culture method, and the bacterial compositions were characterized by the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique. The results show that citral had the best bacteriostatic effect and the weakest one was geranium oil. After fumigation with high doses of citral, citronellol and linalool, the total bacterial colonies were found decline by 98.53%, 98.53% and 97.95%, respectively. As a result, the richness and diversity index of airborne bacteria also declined significantly. In addition, the PCR-DGGE profile indicates that citral and citronellol might further improve the antibacterial effect. Our study has demonstrated that, as a kind of purifying agent for airborne microorganisms, plant-derived extracts have good prospects for decontamination of museum exhibition halls.

Abstract:In this study, we evaluated the age-induced degradation of wood structural components of the Changchun Palace in the Forbidden City. The wooden structural component (stand column) samples were taken from the interior of the main shrine (C1) and the exterior of the shrine on the south side (C2). Because of the location of C2 in an area where it has long been exposed to natural environmental conditions such as ultraviolet rays in sunlight, it could be seen to be severely degraded by visual evaluation. The columns were determined to have been made of larch wood (Larix gmelinii (Rupr.) Kuzen.). A variety of scientific methods, including X-ray diffraction (XRD), derivative thermogravimetry (DTG) and infrared spectroscopy (IR) were used for further analyses. The results show that the cellulose, lignin and hemicellulose of both C1 and C2 samples have degraded over the years, but the degree of degradation of the cellulose of C2 is more remarkable than that of C1, due to the long-term exposure to ultraviolet light in sunlight. DTG analysis also shows the hemicellulose in C2 had similarly degraded, with the result that the relative crystallinity of C2 is much lower than that of the larch wood used inside the shrine. Furthermore, analyses of chemical group changes by IR spectroscopy show that absorption peaks of C1 and C2 samples have weakened or disappeared at 1 732 cm-1, 1 635 cm-1, 1 510 cm-1 and 1 460 cm-1, indicating that chemical compositions of these larch wood samples have changed markedly, especially for C2. It is also noted that the absorption peak of C2 at the wave number of 1510 cm-1 which represents skeleton vibration of benzene ring originating mainly from lignin has disappeared. This suggests that photodegradation (degradation of lignin primarily due to irradiation of ultraviolet light) would be the main reason for the aging of C2.

Abstract:In order to explore the storage life of paper, we carried out dry-heat accelerated aging experiments on bamboo paper, Xuan paper, newsprint, bible paper and mulberry paper, and evaluated their main physical and chemical indicators (yellowing value, tensile index, tearing index, folding endurance index, degree of polymerization, copper number and cold extraction pH value) before and after aging. Subsequently, the physical and chemical indicators of aging were studied by Pearson rank correlation coefficient, whereby the storage life of paper could be predicted. The results show that tensile index, copper number and degree of polymerization of all these five kinds of paper correlate well with aging time. In terms of yellowing value, pH value and tearing index, some but not all kinds of paper show very good correlations (correlation coefficient above 0.9). However, a good correlation between folding endurance index and aging time was seen for only one kind of paper. Therefore, we believe that tensile index, degree of polymerization and copper number are favorable indicators for predicting the storage life of most papers.

Abstract:Known as the first enclosed earthen site museum in China, the Outer Burial Pits of the Han Dynasty Yang Mausoleum have accumulated more than 7 million pieces of environmental monitoring data of various types. However, due to limitations of big-data mining, utilization of the monitoring data is insufficient and the accuracy of forecasting models is low. In order to solve the problems, a big-data machine learning method, known as the extreme learning machine (ELM), was introduced for temperature analysis and forecasting. The results show that ELM can analyze the annual temperature monitoring data effectively and predicts the instantaneous temperature trends in the future. The introduction of this method represents a useful reference for preventive conservation and management of historical sites.

Abstract:Yangzhou (called Guangling in ancient times) is one of the most important areas for Han Dynasty lacquerware in terms of collection, exhibition, conservation and research. In order to investigate the techniques for making the lacquerware unearthed from the Han Dynasty “Qie Mo Shu” Tomb in Yangzhou, a variety of methods, including super depth-of-focus screen microscopy, Fourier transform infrared spectroscopy (FTIR), laser Raman spectroscopy (LRS), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), and X-ray diffraction (XRD) were used to study three lacquerware specimens from this site. The results show that the lacquerware body is composed of linen cloth-based materials, which are bonded together with lacquer and plaster layers containing granular silica (SiO₂) and hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂]. The lacquer film contains no tung oil, and the red pigment contains cinnabar (HgS). This research provides information relevant to the future conservation of these lacquerware objects and useful clues for further explorations of the official and private attributes of Han Dynasty lacquerware unearthed in Yangzhou.

Abstract:Pit K0007, located at the northeast corner of the outer walls of the Mausoleum of the first Qin Emperor, was excavated in the year 2 000, and 46 life-sized bronze waterfowls were unearthed from this pit. According to the report on archaeological excavation, these bronze waterfowls suffered from various diseases because of their harsh burial environment, as well as natural and man-made damage to the pit. Bronze crane No.23 is particularly exquisite and vivid. In order to restore and conserve this precious artifact, we developed a scheme based on its preservation state, disease state and relevant documents. After several essential technical procedures of restoration such as gluing, cleaning, consolidation and pin-connection, the bronze crane finally achieved an ideal exhibition effect.

Abstract:At Mozuizi in Wuwei, a printed silk bag was unearthed from a Han Dynasty tomb. It is now stored at the Gansu Provincial Museum. However, conservation and restoration for this bag is urgently needed because of severe breakage, contamination and rot. In addition to doing instrumental analyses to look for clues, we referred to literature in order to develop a restoration scheme, and finally inferred the shape of the silk bag. Restoration for the silk bag included using the supporting method, selecting modern fabrics with the similar style as backing and applying the crepe reinforcement technology on the surface. The key technical points were also recorded and summarized. After restoration, the silk bag features a clear shape and texture, harmonious color and luster, increased overall firmness, and an enhanced ornamental effect. The ideal restoration effect could have referential significance for similar restoration and research in the future.

Abstract:After archaeological excavations, in which the stable environments of mural tombs are broken, a variety of diseases may occur because of microenvironmental changes. In order to explore the effect of microenvironmental changes, a long-term monitoring of air temperature and humidity, and soil temperature, water content and conductivity was carried out in a simulated mural tomb at Shaanxi Normal University. The results show that external environmental changes can influence the microenvironment inside the tomb. The higher the soil is from the tomb bottom, the more significantly are the temperature and humidity changes, and also the more easily crisp powder formation and other diseases can happen. In addition, ion chromatography, X-ray diffraction (XRD), anti-damping drilling and some other methods were used for qualitative and quantitative analysis of the soluble salts in soil. The results show that the anion and cation contents of soil are positively correlated with the soil depth. The salts precipitated on the soil surface mainly contain sodium sulfate and calcium sulfate, which can easily cause the disease of crisp powder formation due to the constant microenvironmental changes. Based on the systematic research on microenvironments of mural tombs conducted, we can propose effective regulations. We are looking forward to providing more scientific bases for site protection.

Abstract:The Epang Palace Site was selected as a typical example of a large-scale earthen archaeological site, to investigate the effects of plants on it. The combination of on-site investigation using the transect method, image analysis and soil sampling was carried out to analyze the distribution of the planting area, root-induced cracks and soil characteristics. The results show that the main cause of damage to the site is plant roots, which, in combination with rain erosion, weathering and human damage, seriously threaten the site. The root-induced cracks and the effects of plant roots on the soil environment from species such as Ziziphus jujuba Mill. and Ailanthus altissima play a key role among all the various threats to the soil ruins of Epang Palace. The types of damage mainly include earth cracks and collapses, shrinkage of wall bases, surface exfoliation, and many gullies and holes which are quite unique for earthen archaeological sites in semi-arid areas. This research could help not only to reveal the mechanism of planting effects on earthen archaeological sites, but also provide theoretical and technical support for plant selection for site conservation.

Abstract:In order to protect unearthed bronze artifacts, it is necessary to remove any powdery rust found on the wares. Powdery rust is mainly composed of atacamite and paratacamite, both of which have distinctive infrared spectral characteristics, making the rust identifiable by infrared microspectroscopy. Compared with the traditional compression-type Fourier transform infrared (FTIR) spectroscopy, the transmission infrared microspectroscopy method we used is faster and a more sensitive way to analyze samples with less consumption of sample, and no requirement for tabletting. In this study, the transmission infrared microspectroscopy was used to analyze the bronze corrosion products on bronze test samples, namely bronze relics from the laboratory archaeological and conservation project for the coronet of Emperor Sui Yang’s Empress Xiao, located in Caozhuang of Yangzhou, Jiangsu Province. The results show that this method can identify powdery rust efficiently and accurately.