The development of convolutional neural network (CNN) techniques has advanced image classification in various fields, including autonomous vehicles, medical care, and cultural heritage science1, 2-3. This study employed CNN techniques to process large numbers of micrographs, build a dataset of pigment microstructures, and classify their manufacturing processed. As research that automatically classified such micro-morphological features using CNNs remains limited, this study provides an early framework demonstrating the potential of deep learning-based morphological analysis in pigment research within cultural heritage. A dataset of 2654 SEM micrographs was established and analyzed using four architectures-AlexNet, GoogLeNet, ResNet, and VGG. Evaluation metrics such as accuracy, precision, recall, F1-score, and confusion matrix were applied, with VGG16 achieving the highest overall performance. The CNN models reached over 97% accuracy using an 80/20 split for cross-validation. These results indicate that the manufacturing process of a pigment can be inferred rapidly by comparing and classifying its micrographs.

You-Man, a traditional adhesive material in polychrome painting of Ancient Chinese architectural, is made by mixing tung oil, flour, and lime water. However, You-man has notable shortcomings, including a long drying time and poor aging resistance, which can lead to cracking and peeling of the pigment layer in architectural polychrome painting, thereby affecting the lifespan of the painted cultural heritage. This study aims to obtain a modified You-Man with a shorter drying time and better weather resistance by adding various functional modification materials, such as toluene diisocyanate (TDI), silica, and bentonite. The modified You-Man from the three groups were evaluated for drying time, hardness, adhesion, hydrophobicity, thermal expansion coefficient, moisture expansion coefficient, moisture absorption, and aging resistance. Comprehensive performance evaluations revealed that group Modified You-Man 2 (MYM-2, is composed of 58.00 % You-Man, 2.00 % TDI, and 40.00 % silica), demonstrated the best performance: compared to traditional You-man, the drying time was reduced by 75.00 %, the thermal expansion coefficient decreased by 48.69 %; the moisture expansion coefficient decreased by 51.79 %. Furthermore, no significant structural damage was observed after 100 days of accelerated aging experiment. MYM-2 has been initially used for the restoration of the polychrome painting on ancient architecture in the Forbidden City, and after nearly two years of outdoor testing, it has shown promising results. Notably, this study introduces a novel approach combining thermomechanical analyzer (TMA) and module of humidity generation (MHG) to test the thermal and moisture expansion coefficients of key You-Man and wooden substrates, providing valuable guidance for assessing the weather resistance of the modified You-Man.

Palm leaf manuscripts, crafted from specially treated palm leaves, are invaluable historical documents. However, they degrade and tend to become brittle over time. To date, plant essential oils and glycerin are the used materials to improve the flexibility of palm leaf manuscripts, but the effective duration of these materials is short due to their volatility. This work introduces ionic liquids, a nonvolatile and stable material, to achieve durable toughening of the palm leaf manuscripts. We select 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]), one of the most used ionic liquids, as the subject of research. We find that [BMIm][BF4] does not alter the palm leaf manuscripts' appearance and significantly improves their tensile strength and fracture toughness by 39.9 and 101.0%, respectively, while reducing the bending modulus by 25.7% and increasing the bending fracture deflection by 2.6 times. Notably, [BMIm][BF4]'s toughening effect for palm leaf manuscripts is sustainable for over 2 months, outperforming traditional methods that last only about 1 week. Even under harsh conditions, such as low humidity, high temperatures, alkalinity, and UV exposure, [BMIm][BF4] still maintains its effectiveness. Through the analysis of its composition, structure, and theoretical simulation, we reveal that [BMIm][BF4] penetrates the manuscripts, filling the pores between the inner structure of them and adsorbing strongly with cellulose. This enhances load transfer and reduces the stress concentration, resulting in increased toughness. This research provides innovative materials for palm leaf manuscript conservation and deepens our understanding of their mechanical properties.

Palm Leaf Manuscripts are valuable cultural assets, and understanding the impact of environmental factors on their properties is essential for effective conservation. This study simulated aging to assess the effects of relative humidity (RH) on the manuscripts using various techniques, including SEM, DVS, TMA, FT-IR, and XRD. The results show that exposure to extreme dry or humid conditions negatively affects the manuscripts. In dry conditions, they experience bending, cracking, reduced mechanical strength, lower hygroscopicity, and chemical degradation. In humid conditions, fungal growth compromises the manuscripts’ structure. These changes affect color, gloss, hygroscopic behavior, cellulose crystallinity, and thermal stability, weakening mechanical properties. Manuscripts stored at 50% RH showed no significant damage, suggesting that this level is optimal for their preservation. This study provides insights into the degradation mechanisms of Palm Leaf Manuscripts under different humidity conditions and offers recommendations for their preservation.

This study investigates the classification of pigment-manufacturing processes using deep learning to identify the optimal model for cultural property preservation science. Four convolutional neural networks (CNNs) (i.e., AlexNet, GoogLeNet, ResNet, and VGG) and one vision transformer (ViT) were compared on micrograph datasets of various pigments. Classification performance indicators, receiver-operating characteristic curves, precision–recall curves, and interpretability served as the primary evaluation measures. The CNNs achieved accuracies of 97–99%, while the ViT reached 100%, emerging as the best-performing model. These findings indicate that the ViT has potential for recognizing complex patterns and correctly processing data. However, interpretability using guided backpropagation approaches revealed limitations in the ViT ability to generate class activation maps, making it challenging to understand its internal behavior through this technique. Conversely, CNNs provided more detailed interpretations, offering valuable insights into the learned feature maps and hierarchical data processing. Despite its interpretability challenges, the ViT outperformed the CNNs across all evaluation metrics. This study underscores the potential of deep learning in classifying pigment manufacturing processes and contributes to cultural property conservation science by strengthening its scientific foundation for the conservation and restoration of historical artifacts.

This study examines how natural aging affects the hygroscopic, kinetic, and thermodynamic properties of ancient Tibetan Palm Leaf Manuscripts. The results show aging increases equilibrium moisture content and hygroscopicity, with a noticeable hysteresis effect, suggesting enhanced moisture stability at low to moderate humidity. The GAB and H-H models indicate aging accelerates cellulose degradation, adds adsorption sites, and promotes physical adsorption. Kinetic studies reveal a faster moisture absorption and release rate with aging, especially under varying humidity. Thermodynamic analysis shows that as moisture content rises, the adsorption and desorption processes become more spontaneous. Infrared spectral analysis confirms significant degradation of cellulose and hemicellulose, increasing hydroxyl groups and hygroscopicity. The study suggests that these manuscripts are best preserved in a controlled environment with moderate humidity (50-60% RH) and cooler temperatures to maintain moisture stability and flexibility while preventing damage from excessive fluctuations.

As archaeological endeavors progress in our nation, shipwreck artifacts are discovered and excavated, and their preservation is increasingly prioritized. Various degradation factors in the burial environment cause irreversible changes in the picroscopic morphology, chemical composition. cellulose crystallite structure, and physical and mechanical properties of Archaeological wood. Therefore, it is crucial to accurately assess the preservation condition of shipwood before implementing conservation measures. This study aims to ensure the effective overall preservation and protection of the shipwreck artifacts xcavated at the Huai'an Watergate Site Park of the Grand Canal in Jiangsu Province. To this end, representative shipwreck wood samples were selected, and their degradation degree was comprehensively evaluated. First, the wood species of the Archaeological wood were identified, and the degradation level was preliminarily classified based on the maximum water content MWC) and basic density (BD). Additionally, the relative crystallinity of wood cellulose was calculated using X-ray diffraction (XRD), and the thermal stability of the archaeological wood was determined through thermogravimetric analysis (TGA). Based In these analyses, infrared spectroscopy (FTIR) was used to detect changes wood's chemical structure. The results showed that The selected archaeological wood is Cinnamomum sp. and can be classified into three degradation levels, slight moderate and severe. The relative crystallinity of cellulose in sound wood is 58. 87%, while that in archaeological wood ranges from 17.16% to 36.42%, indicating degradation in the crystalline regions of the cellulose. The maximum pyrolysis temperature of sound wood 366.73 degrees C. whereas that of archaeological wood ranges from 340.38 C to 365.67 C. suggesting that large molecules in the Archaeological wood gradually decompose into smaller molecules, Infrared spectroscopy revealed that hemicellulose degradation was the most severe during the degradation process, with the characteristic peak at 1 735 em' attributed to the acetyl groups in the side chains of hemicellulose, completely disappearing in moderately and severely degraded samples. As the degradation level creased, the intensity of the characteristic peak at 897 cm gradually decreased, and the characteristic peak at 1 424 cm Shifted to a lower wavenumber, indicating that some hydrogen bonds in the cellulose were gradually destroyed as the degradation The lignin structure remained relatively stable, with the intensity of the characteristic peaks related to the romatic skeleton significantly increasing. The ratio of lignin to cellulose further confirmed the above results. This study Brovides a more intuitive evaluation of the preservation status of archaeological wood and offers reliable fundamental data for the Subsequent conservation work of the shipwreck artifacts.

Mingjiao Temple is located in Chengdu,Sichuan Province.The Juehuang Hall is the only surviving structure of the original Mingjiao Temple complex.The main part of the hall was constructed during the early Hongwu period of the Ming Dynasty(1368-1382)and was completed no later than the first year of the Chenghua reign(1465).The interior of Juehuang Hall retains a significant number of Ming Dynasty murals,which exhibit the distinctive characteristics of the official architectural style of the Northern country.These murals are a rare example of Ming Dynasty architectural painting and hold significant research value.Previous research on the paintings in the Juehuang Hall has focused on their form and aesthetic style,with no scientific analysis of their production techniques and materials.This study employs a high-resolution digital microscope,laser Raman spectrometer,scanning electron microscope,and energy dispersive spectrometer to analyze and identify the pigments from the paintings in the Juehuang Hall.The results indicate that the green pigments in the Mingjiao Temple's Juehuang Hall paintings are malachite and copper chloride,the red pigments are iron oxideand red lead,the white pigment is lead white,the blue pigment is indigo,and the black pigment is carbon black.Furthermore,the eaves paintings within the Juehuang Hall exhibit multi-layered paintings and the practice of mixing pigments for color adjustment.Synthetic ultramarine and Paris green are absent in these eaves paintings,which were commonly used in the Qing Dynasty's middle and later periods.The painting technique,characterized by the direct application of pigments onto the wooden components without a preparatory ground layer,suggests that these paintings are likely remnants from the Ming Dynasty,aligning with the documented period of the paintings'creation.This study is the first scientific analysis of the production techniques and materials of the Juehuang Hall paintings,and the preliminary findings have enriched the understanding of the application of pigments in Ming Dynasty architectural paintings,providing a reference for subsequent research and conservation efforts.

Cultural heritage objects, including traditional Chinese polychrome paintings on architectures (Caihua) and wooden architectural components, frequently exhibit surface defects that are highly sensitive to environmental factors, resulting in progressive deterioration. However, due to limited data acquisition methods and quantitative analysis models, the stability and risks of defects such as cracks during environmental changes remain unclear. This study integrates photogrammetry and digital image processing to investigate through-cracks and craquelures on the surface of a well pavilion within the Palace Museum, Beijing. We confirmed the activity of these cracks, quantified crack widths, and studied the environmental influences on their development. Over a monitoring period of more than 15 months, the widths of seven cracks on four beams were measured alongside various environmental factors. Correlation analyses identified air humidity as the most significant factor influencing crack width fluctuations (p < 0.01). Numerical simulations revealed that short-term humidity exposure induces surface swelling and crack closure, whereas prolonged humidity leads to internal moisture transport and crack reopening. Furthermore, fitting parameters indicating the severity of crack variation correlated well with the degradation levels of the wooden components. In summary, this study establishes a monitoring and quantification procedure for assessing crack activity, explores the influence of humidity through numerical simulations, and identifies a potential indicator for the non-destructive assessment of timber component stability. The proposed framework offers an exploratory approach to addressing critical challenges in the health monitoring of wooden architectural components.

Lignin-like materials share chemical similarities with wood and exhibit excellent mechanical properties along with resistance to aging and microbial degradation. This study focuses on eugenol as a target lignin-like monomer. Three eugenol nanoemulsions with concentrations of 10%, 20%, and 30% were prepared using surfactant Pesticide Emulsifier 1602 and co-surfactant diethylene glycol mono butyl ether (DEGBE). Laccase facilitated the in-situ polymerization of eugenol on the cell walls of waterlogged archeological wood (WAW) from the Nanhai No.1 shipwreck at temperatures of 35 degrees C degrees C, 45 degrees C, and 55 degrees C for dehydration and consolidation purposes. The 30 wt% eugenol emulsion at 45 degrees C showed the best consolidation effectiveness, with a minimal shrinkage rate of 3.62% and a 400-1000% increase in bending strength compared to controls. The polymer reinforced the decayed wood while preserving cellular lumens, offering an innovative, environmentally sustainable conservation method for WAW.

The Nanhai No. 1 shipwreck is an ancient wooden ship in the Southern Song Dynasty. Currently, serious challenges of microbial diseases exist on the hull wood. This study aimed to obtain microbial samples from the ship hull in December 2021 and analyze the microbial diseases through scanning electron microscopy and high-throughput sequencing to preserve the Nanhai No. 1 shipwreck. The biodegradation mechanism of diseased microorganisms was explored through whole genome sequencing and the detection of enzyme activity and gene expression levels of diseased microorganisms under different conditions. The results showed that there was obvious fungal colonization on the surface of the hull wood and Fusarium solani NK-NH1 was the dominant disease fungus on the surface. NK-NH1 has strong cellulose and lignin degradation ability. Its whole genome size is 52,389,955 bp, and it contains 17,402 genes. It has a variety of key enzyme genes involved in cellulose and lignin degradation. The NK-NH1 dominant degrading enzyme lignin peroxidase has the highest enzyme activity at pH = 4, NaCl concentration of 30%, and FeSO4 concentration of 50 mg/L, while laccase has the highest enzyme activity at pH = 4, NaCl concentration of 10%, and FeSO4 concentration of 100 mg/L. The above research results prove that NK-NH1 is a key fungus to the biodegradation of ship hull wood when it is exposed to air, low pH, high salt, and rich in sulfur iron compounds. This study provides a theoretical basis for the preservation of the Nanhai No. 1 shipwreck.

Scientific analysis of excavated pottery reveals critical archaeological insights, yet data on Han Dynasty pottery remains limited. This study focuses on pottery artifacts excavated from the Daqu burial site in Beijing, renowned for their polychrome decorations and size. Utilizing optical microscopy (OM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray Fluorescence (XRF), this study examined five substrate samples sourced from fragments of pottery towers and ellipse-shaped dishes. All samples exhibited similar inclusions and the same firing atmosphere. The mineralogical analysis indicated that quartz and feldspar are predominant components, with minor constituents like chlorite and kaolinite observed in the coarse pottery of the ellipse-shaped dish. Minor mineral variations suggest differences in firing temperatures. The resemblance between low-value pottery cups and delicate polychrome towers suggests they were crafted locally. These findings advance our understanding of ceramic materials and techniques in late Eastern Han Dynasty Beijing, providing crucial insights for future studies on ancient Chinese economy and society.

Tetraethoxysilane (TEOS) is the most commonly used silicon-based reinforcement agent for conserving art relics due to its cost-effectiveness and commercial maturity. However, the resulting silica gel phase is prone to developing cracks as the gel shrinks during the sol–gel process, potentially causing severe damage to the objects being treated. In this study, dodecyltrimethoxysilane (DTMS) was introduced into TEOS to minimize this shrinkage by adding elastic long chains to weaken the capillary forces. The gel formed from the DTMS/TEOS hybrid material was transparent and crack-free, featuring a dense microstructure without mesopores or micropores. It exhibited excellent thermal stability, with a glass transition temperature of up to 109.64 °C. Evaluation experiments were conducted on artificially aged, handmade bamboo paper. The TEOS-based hybrid material effectively combined with the paper fibers through the sol–gel process, polymerizing into a network structure that enveloped the paper surface or penetrated between the fibers. The surface of the treated paper displayed excellent hydrophobic properties, with no significant changes in appearance, color, or air permeability. The mechanical properties of the treated bamboo paper improved significantly, with longitudinal and transverse tensile strengths increasing by up to 36.63% and 44.25%, respectively. These research findings demonstrate the promising potential for the application of DTMS/TEOS hybrid materials in reinforcing paper relics.

Palm leaf manuscripts, which are crucial carriers of historical, religious, scientific, and artistic information in East and Southeast Asia, specifically encapsulate significant aspects of Buddhist culture and thus require comprehensive research and preservation efforts. The base material of palm leaf manuscripts is processed palm leaves, which are hygroscopic and profoundly affected by environmental humidity. Currently, there is a research gap regarding the impact of traditional processing crafts and natural aging on the hygroscopicity of palm leaf manuscripts. Utilizing dynamic water vapor sorption (DVS), the hygroscopic properties of palm leaves from various years were assessed before and after traditional processing in Yunnan Province, China. The results show that traditional processing slightly increases the equilibrium moisture content (EMC) in environments with 0 to 60% relative humidity (RH), but significantly lowers EMC in high humidity environments, with reductions up to 19.01%. Additionally, hysteresis doubled post-processing, indicating enhanced stability under fluctuating humidity conditions. Sorption models suggest that traditional processing increases the number of adsorption sites while reducing physical adsorption or capillary condensation. FT-IR (Fourier-transform infrared spectroscopy) analysis indicates that the relative contents of cellulose and hemicellulose were reduced by 39.90% and 3.97%, respectively. Degradation occurring in both the crystalline and amorphous regions of cellulose. After natural aging, the hygroscopicity of processed palm leaves improved across the entire humidity range of 0 to 95%, and there was a slight increase in hysteresis. This is due to the increase in both adsorption sites and physical adsorption capabilities. FT-IR results also indicate that the relative contents of cellulose and hemicellulose were decreased by 57.52% and 19.83% after nature aging, respectively. These findings confirm that traditional processing improves the writability and humidity resilience of the leaves, while natural aging enhances their overall hygroscopic properties. This research contributes to our understanding of how humidity damages palm leaf manuscripts. aids in determining optimal RH ranges for storage, and assesses the effectiveness of consolidation treatments in their long–term preservation.

The Dingtao M2 tomb, the largest and best-preserved imperial “Huangchangticou” tomb in China, holds great significance for its conservation. Currently, varying degrees of microbial degradation are occurring on the surfaces of the M2 tomb. This study aimed to determine the microbial diversity of the M2 tomb and its surrounding environment during July 2021 and August 2022. High-throughput metagenomic sequencing revealed that the dominant fungus on the surface of the tomb chamber was Dacrymyces stillatus (DTT1) in July 2021, which changed to Talaromyces pinophilus (DTT2) in August 2022. Enzymatic activities for cellulose and lignin degradation suggested that DTT1 has high levels of manganese peroxidase, lignin peroxidase, laccase, and cellulase. The wood of the tomb contained higher levels of Fe2+ and Ca2+, and experiments with different concentration gradients of these ions in the culture medium revealed that DTT1 exhibited greater activity of cellulose and lignin degradation in environments with higher concentrations of Fe2+ and Ca2+. DTT2 degraded both cellulose and lignin. Lastly, a laboratory plate inhibition experiment demonstrated that isothiazolinone fungicide had a significant fungicidal effect on these two dominant fungi. This study provides valuable data and a theoretical basis for the preservation of the M2 tomb and other wooden cultural relics.

Hygroscopicity is one of the most important properties of wood and plays a decisive role in its dimensional stability. In this context, conservation plans for waterlogged archaeological wood (WAW) and relevant waterlogged artefacts must be created. The size of the sample required for a moisture sorption assessment may affect the results for (and thus the perception of) the hygroscopicity of a testing artefact. Herein, to investigate the effects of the sample size on the hygroscopicity of WAW as measured via dynamic vapour sorption (DVS), typical WAW and recent (i.e., sound) wood are processed into four differently sized samples, ranging in thickness from 200 mesh to millimetre. The equilibrium moisture contents (EMCs) of the wood samples are simultaneously measured using simultaneous DVS. The sorption isotherms show that the EMC values of the recent wood at each relative humidity increase as the sample size decreases, with the superfine powder sample achieving the highest EMC of all of the recent samples. Although the WAW has a higher EMC than that of recent wood, the effect of the size of the WAW sample on its hygroscopic properties is surprisingly not as pronounced as that for the recent wood. In addition, the hysteresis between the samples of different sizes of the archaeological wood is significantly smaller than that for the reference samples. Furthermore, regarding the standard deviations of the parameters obtained from the Guggenheim Anderson de Boer and Hailwood–Horrobin models, the values for WAW are all much smaller than those for the reference wood. This further verifies the disappearance of the size effect of the hygroscopicity for WAW.

A greater understanding of moisture sorption behaviour of aged wooden structural components, which has a close relationship with dimensional stability, is required to effectively evaluate and preserve historical artefacts. This study focused on the effects of aging on Baotou beam samples from a Chinese historical wooden building. An analysis of the sorption isotherms and hysteresis loops of a naturally aged, decayed sample (AOS), an aged sound sample (AIS), and a reference sample (RS), using classical sorption isotherm models revealed that the moisture sorption behaviour of samples from the same growth ring in a Baotou beam can differ significantly. AOS showed higher hygroscopicity than AIS, and both these samples were more hygroscopic than RS. Furthermore, the mono/multilayer moisture contents of AOS were always higher than those of AIS and RS. In addition, Fourier transform infrared, second-derivative infrared, and two-dimensional correlation infrared spectroscopy were used to investigate chemical changes in the samples. The relative hemicellulose and lignin contents of the samples changed significantly with wood aging. Furthermore, AOS exhibited the highest calcium oxalate content, which may be associated with fungal infections. Overall, these results provide valuable insights into the effects of aging on wood samples and the dimensional stability of timber structures, which could inform future research on methods for the preservation or restoration of aging timber structures.

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.

Waterlogged archaeological wood samples may degrade during long-term immersion in microbial-activity environments, which causes its biodegradation. Simultaneous dynamic vapor sorption (SDVS) and two-dimensional correlation infrared (2D COS-IR) spectroscopy reveal the degradation inhomogeneity of waterlogged fir wood from the Shengbeiyu shipwreck. The waterlogged and reference wood exhibit type II sorption isotherms. The equilibrium moisture contents of waterlogged archaeological fir wood from a decay region (WFD) were 22.5% higher than those of waterlogged archaeological fir wood from a sound region (WFS). WFD exhibits a higher measurable sorption hysteresis than WFS, implying greater variation in the surface moisture content in the WFD region compared to the WFS region, which may compromise the dimensional stability of the shipwreck. 2D COS-IR spectra confirmed the inhomogeneous degradation of the waterlogged wood via numerous mechanisms. The efficacy of SDVS and 2D COS-IR spectroscopy in the evaluation of the degradation state of waterlogged wood was demonstrated. This study verifies the existence of hygroscopic and chemical differences between visually similar samples from the same shipwreck.

故宫奉先殿是明清两代皇帝祭祀祖先的家庙,保留了为数不多的清初彩画,是研究清初彩画的珍贵实物.该研究通过扫描电子显微镜、傅里叶红外光谱、热裂解气相色谱-质谱、X射线衍射、同步热分析仪、碘显色法等多种分析方法首次对奉先殿前殿内檐彩画的地仗样品进行制作材料和工艺研究,发现奉先殿地仗中无机物主要有砖灰、石灰,有机物有桐油、淀粉,未检测出血料,研究结果与文献所载清代官式做法一致.该研究是首次对奉先殿彩画地仗的科学分析,是对稀有清初官式彩画地仗研究的有益补充.