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In 2013, several tombs were discovered and excavated in Southeastern Beijing, China, yielding various burial products. Among these were pottery towers, a representative artifact of the Han Dynasty rarely found in the area. Many studies on architectural aspects, such as construction type and construction situation, have been conducted based on the excavated pottery towers, but only a few have examined their raw materials or pigments. In this study, black, white, and red pigments were identified as carbon black, calcite, and cinnabar, respectively, through a multi-analysis approach. The manufacturing method of the pigment was established based on the crystal form and particle size of the pigment, by factoring in the pigment characteristics, which cannot be distinguished by component analysis and crystal structure analysis. We recommend that a continuous database be prepared and used in the future, not only for an interpretation of ancient pigments but also to identify the factors to be considered (physical characteristics, such as pigment particle size among others) when estimating the manufacturing process and conservation treatment.

Sắc tố độc hại nổi tiếng của Carl Wilhelm Scheele, thường được gọi là “màu xanh Scheele”, thường tạo ra một hỗn hợp các sản phẩm với thành phần hóa học không xác định. Việc xác định chính xác sắc tố này đã bị giới hạn ở các phương pháp phổ Raman và phân tích gián tiếp bằng các phương pháp FTIR và XRD. Mặc dù đã có những kỹ thuật này, nhưng các trường hợp sắc tố được báo cáo trong các mẫu di sản lại rất hiếm, cho thấy rằng màu xanh Scheele ít khi được báo cáo không phải vì việc sử dụng không thường xuyên mà vì những thách thức trong việc xác định của nó. Về sự phân hủy của các sắc tố xanh Cu-As, những giả định phổ biến cho rằng sự phân dissociate trong điều kiện pH axit, tạo ra các ion asen và đồng di động, tiếp theo là quá trình oxy hóa thành As(V), có thể đồng kết tủa với các ion Fe, Al và Ca. Nghiên cứu này reproduces việc chế tạo màu xanh Scheele bằng cách sử dụng các công thức lịch sử, tập trung vào việc duy trì pH của dung dịch arsenit ở mức 9.3. Nghiên cứu khám phá mối quan hệ giữa nó với màu xanh Emerald, các thách thức liên quan đến việc xác định của chúng và giải quyết những hiểu lầm phổ biến về sự phân hủy của các sắc tố này. Việc duy trì pH ở mức 9.3 đã chứng tỏ ảnh hưởng trong việc thu được một sản phẩm tinh thể với tín hiệu Raman mạnh, phù hợp với quang phổ được chấp nhận rộng rãi của màu xanh Scheele. Tuy nhiên, quang phổ Raman từ các mẫu Cu-As vô định hình liên tục thể hiện các dải rộng ở 288 và 845 cm−1, dẫn đến một đề xuất sửa đổi cho một đại diện kép của sắc tố này: dạng “thông thường” với các dải rộng và dạng “không thông thường” hoặc tinh thể như đã được báo cáo trong tài liệu. Việc chứng minh rằng dạng tinh thể chia sẻ quang phổ Raman và FTIR gần như giống hệt nhau ám chỉ thành phần hóa học giống hệt Trippkeite. Bằng chứng được trình bày làm nổi bật rằng các sắc tố dựa trên Cu-As chứa ion đồng tự do, arsenit và arsenat dễ di động, thách thức các con đường phân hủy thường được mô tả. Giả thuyết được trình bày ở đây, rằng tổng hợp màu xanh Emerald có thể vô tình tạo ra một lượng nhỏ màu xanh Scheele, cảnh báo về việc xác định sắc tố bằng phương pháp quang phổ Raman. Thêm vào đó, nghiên cứu tiết lộ, lần đầu tiên, sự hiện diện của màu xanh Scheele trong một quyển sách, với các hạt thể hiện dạng spherulite, thách thức việc xác định màu xanh Emerald chỉ dựa trên hình thái học.

On the 26th of April 2010, while performing routine electrical work, a lost sculpture group of famous Russian sculptor Vladimir Beklemishev (1861–1920) titled ‘Fugitive Slave’ was found inside a wall of the Winter Palace in St. Petersburg, Russia on the landing of the staircase to the second floor. This sculpture was created under the influence of the anti-slavery novel “Uncle Tom's Cabin” by American author Harriet Beecher Stowe and was presented at the World's Columbian exposition in Chicago in 1893, devoted to the 400th anniversary of the discovery of America by Columbus. The sculpture was made from gypsum and coated with a covering that imitated bronze. At the moment of finding, the sculpture was heavily damaged and needed serious restoration, including repairing of the bronze imitation layer. This situation permitted us to do a detailed examination of the materials and techniques used in making this bronze-like covering. The sculpture was made by Beklemishev in Italy in 1891. At the time of writing, ‘Fugitive Slave’ has been restored to its former glory and can be admired in the State Hermitage museum in St. Petersburg, Russia. Studying the cross-sections of tiny fragments of bronze-like covering from different parts (bright and dark) showed that the coating was multilayered. Different parts of the covering also show large differences in structure. Pigment composition of each layer was investigated by SEM-EDS (Scanning Electron Microscopy-Energy Dispersive Spectroscopy). Relatively pure copper filings and scrapings were applied to imitate a solid bronze layer. The top thin layer, which imitated a bronze patina, was made of a copper arsenic paint. GC/MS analysis of the fatty acids showed the presence of drying oil. The presence of erusic acid, a biomarker, showed presence of the Brassicaceae seed oil. A small amount of pinaceous resin and dammar were discovered as well. The top thin layer, however, seemed to contain linseed oil (based on fatty acids ratios - A/P = 1.5; P/S=1.6). Besides that, the surfaces of the dark parts were covered with a very thin layer of beeswax. It is believed that this is the result of conservation treatment, rather than applied by Beklemishev himself. PCA analysis of the selected ion monitoring chromatograms of the proteinaceous materials showed the presence of egg in practically all layers of bright fragments and in the bottom layers of the dark fragments. According to literature, a mixture of drying oil, egg and resins was often used for priming in polychromic paints on stone in Italy. Since Beklemishev made ‘Fugitive Slave’ during his time there, it is possible that he used these materials. However, looking at the middle layers of the dark fragments, evidence for casein as proteinaceous ingredient was also found. Since the layers where casein was found are thicker, the presence of casein indicates that a casein-oil mixture was possibly applied as binding to get more pasty paint films. This way one may conclude that different binding materials were used for different layers. These analyses give a great insight into the way imitation of bronze of this sculpture was made and allow us to learn more about this specific technique.

For the first time, this paper systematises the medieval preparation of black writing inks found in the important thirteenth century Andalusian technical treatise written by Muhammad ibn Idrīs ibn al-Qalalūsī (1210–1308). We present the Arabic version of this extraordinary text (‘The gifts of the wise men on the curiosities of the substances’), and its first English translation, as well as discuss key aspects of the processes that remain missing or are unclear indications. In this work, we studied the iron gall inks based on galls, where no other phenolic source is present. In this pedagogical treatise, the recipes for these black iron-gall inks are organised and classified by the gallnuts extraction method used: boiling (decoction), squeezing and infusion, with water being the only solvent used. The inks selected were reproduced and characterised through a multi-analytical approach. Quantification was performed by HPLC–DAD (high performance liquid chromatography with diode array detectors in the UV–VIS), showing that gallic acid is a minor compound in the gall extracts prepared following al-Qalalūsī instructions. In all the recipes, the higher concentration compounds in the gall extracts are the gallotannins pentagalloylglucose and hexagalloylglucose, ranging from 79 to 50% of the phenolic compounds. This supports the results of Raman and infrared spectroscopies. A comparison with medieval Iberian recipes was also done, which served to reinforce our previous results that show water as the sole solvent extracts with much lower yields than mixed solvents (water plus white wine or vinegar).

The aim of this study was to advance the current understanding on the mechanism of deterioration of historical vegetable tanned leathers and establish new criteria for quantifying their deterioration using micro differential scanning calorimetry (micro DSC) and micro hot table (MHT) method. Ten historical leather objects were investigated to this purpose. The calorimetric indices of macromolecular change identified for fibrous collagen provided quantitative results on the bulk material and deconvolution of DSC denaturation peaks revealed the dynamics of deterioration in historical leather. The results brought clear evidence that long-term natural ageing of leather induces the destabilization of chemically modified collagen thereby promoting its partial de-tanning and allowing micro-unfolding of chemically unmodified collagen. As deterioration continues toward the extreme, collagen molecules become highly unstable allowing for gelatinisation and irreversible denaturation. It is thus explained the coexistence of collagen populations with distinct thermal stability in historical leather. They are grouped in three main structural domains, namely “leather-like”, “parchment-like” and “gelatine-like”, whose mass percentages determines leather stability against further natural ageing and deterioration. As a result of the MHT and micro DSC parameters correlation, a more comprehensive set of criteria, including Tf and Tl values, as well ∆C and ∆T intervals’ lengths, was introduced for better interpreting the shrinking activity of collagen in historical vegetable-tanned leathers and open thus the way for the highly sought in situ evaluation of leather artefacts.

At the heart of bureaucratic practice during Warring States and early Imperial China were regular, small acts of accountancy in which objects and people were marked so that their movements could be kept track of, their quality checked and their numbers marshalled. In the mausoleum complex of the Qin Shihuang (259-210 bc, the First Emperor of the Qin Dynasty), the longer texts and shorter inscribed marks found on the bronze weapons of the Terracotta Army are reasonably well known, and such information helps us to understand aspects of Qin craft organisation and logistics at this crucial period of Chinese state formation. This paper’s modest starting point is a study of two further, less well-known ink inscriptions found on crossbow triggers from Terracotta Army Pit 1. Using multispectral photography, digital microscopy and Raman analysis, we uncover evidence of further marks on the same two triggers that suggest a similar pattern of ‘matching’ marks as suggested by the incised evidence. We also identify the black substance used to make the marks as a soot-based ink. Spatial analysis of both the inked and incised trigger marks then provides wider context for how such marking practices amongst Qin bronze-workers may have operated.

Once printed, books are always accompanied by the smells of volatile organic compounds (VOCs) which are continuously emitted not only by inks but also by papers themselves throughout their lives. Although the VOCs from papers may bring mild discomfort to readers, they are considered as very important factors that feature the degradation of papers and show potential applications in cultural relic appraisal. In this study, an analytical approach based on solid phase microextraction combined with gas chromatography-mass spectrometry (SPME-GC/MS) was proposed for the evaluation of volatile organic compounds (VOCs) emitted by Chinese traditional handmade papers. The VOCs evaluations and artificial aging processes were both applied to recent-made papers and naturally aged papers from a traditional Chinese calligraphy and painting scroll (collected by the National Museum of China). To be noticed, a large number of aliphatic acids, aldehydes, ketones, furan derivatives, benzene series and terpenoid substances indicated that the VOCs signals not only reveal the degradation of paper but also tentatively reflect the storage environment along hundreds of years ago. The semi-quantitative evaluation of markers indicated that the historical paper is under a serious degradation due to the high capacity it releases. Our results provided a path way to get the degradation information of ancient paintings as well as potential realistic applications such as the conservation of paper-based relics and the environmental protection in libraries and museums.

In this work we explore the chemical effects of particulate matter on paper. We exposed paper made of pure cellulose to the environment in different locations in central London, outdoors (in sheltered conditions) and indoors, for a period of up to 6 months. We monitored particulate matter (PM) deposition by counting the particles deposited every month with a scanning electron microscope. We analysed elemental composition of the deposited particles using inductively coupled plasma mass spectrometry. After accelerated degradation of the exposed samples, we determined the degree of polymerisation using viscometry. We observed higher deposition rates and higher metal concentration outdoors than indoors. Elemental analysis of the deposited particles revealed the presence of some transition metals (Fe, Cu, Cr) that can contribute to the degradation of cellulose fibres through the Fenton reaction. By comparing the degree of polymerisation of protected, unprotected and unexposed samples we could determine the relative contribution of PM deposition on the increase of the degradation rate. We found that the surface concentration of iron correlates with the reduction in the degree of polymerisation of the exposed paper. The results suggest that the presence of Fenton metals in PM has a significant effect on the acceleration of the degradation of cellulose. However, we estimate that this will unlikely occur at the levels of area coverage by PM that are typically avoided in indoor heritage through preventive maintenance and cleaning.