Search Results (103)

This article presents a comprehensive analysis of the polychrome paintings on the Flower Peking Opera Theatre in Bozhou, Anhui Province, China. A multi-technique approach was employed, including polarized light microscopy (PLM), X-ray fluorescence (XRF), micro-Raman spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy with energy-dispersive spectrometry (SEM-EDS), and Herzberg staining to determine the composition and methodologies involved in the formation of the pigment layer, the white primer, and the ground layer. The analysis identified cinnabar (red), both artificial ultramarine and Prussian blue (blue), a mixture of barite and gypsum (white), a mixture of chromite and Prussian blue (green), and carbon black (black) in the pigment layer. The ground layer was found to consist of clay and plant fibers (cotton and hemp), while the white prime layer was primarily composed of barite and gypsum. This research provides insights for future conservation and restoration efforts. Full article

This study examines the pigment-dependent photoaging behavior of laboratory-prepared mock-up Chinese lacquer coatings colored with cinnabar, orpiment, and lapis lazuli under high-pressure mercury-lamp irradiation. Colorimetric results showed rapid changes within the first three days, with maximum ΔE values of 14.05 (red), 16.74 (yellow), and 17.97 (blue) after 30 days. Cinnabar-based films exhibited the highest color stability, whereas orpiment and lapis-lazuli coatings underwent pronounced hue shifts and chroma increases. Gloss loss and surface roughness evolution displayed a strong negative correlation: orpiment coatings experienced the most severe degradation, with gloss decreasing by over 60% and surface roughness increasing by approximately 70%, while cinnabar coatings showed the least decline (≈55% gloss loss; ≈27% roughness increase). SEM analysis further revealed extensive cracking and particle fragmentation in orpiment films, moderate surface disruption in lapis-lazuli films, and minimal microstructural damage in cinnabar films. Non-invasive reflection-mode FTIR spectroscopy confirmed these trends, showing minimal chemical change in cinnabar coatings but significant carbonyl growth, C–O–C band broadening, and aliphatic chain cleavage in orpiment and lapis-lazuli coatings. These results highlight the critical role of pigment chemistry in modulating UV-induced degradation pathways. Integrating optical, morphological, and chemical evidence, this study establishes a clear pigment-dependent degradation mechanism and provides valuable guidance for evaluating the long-term stability of lacquered cultural heritage and optimizing modern lacquer formulations. Full article

Urban pollution—especially SO₂ and particulate matter—rapidly darkens and degrades outdoor-exposed wall paintings due to soiling. Laser cleaning has emerged as a cutting-edge solution, offering selective removal of contaminant layers while preserving the integrity of the underlying materials. This study explores the performance of a 355 nm Nd:YAG laser in cleaning artificially aged paint mock-ups coated with real diesel soot and exposed to an accelerated aging test with SO₂ exposure. Traditional mineral pigments—silicates (Egyptian blue, ultramarine blue, and green earth), oxides (chromium green, mars red), and a sulphide (cinnabar)—were applied following fresco and secco (egg yolk) techniques, allowing researchers to uncover how pigment chemistry and binders affect laser sensitivity. Damage thresholds were first determined for each pigment and painting technique via digital photography, stereomicroscopy, and colour spectrophotometry. Cleaning efficacy was then assessed by stereomicroscopy, colour spectrophotometry, Fourier-transform infrared spectroscopy, and scanning electron microscopy. The results revealed clear patterns: silicate pigments exhibit stability under laser irradiation, enabling safe cleaning, whereas mars red and cinnabar remain highly sensitive regardless of the technique. Generally, secco paintings were more susceptible to laser radiation than fresco. These finding provide practical guidance for optimising laser-cleaning protocols while safeguarding the delicate surfaces of historic wall paintings. Full article

Animal-derived adhesives have historically played a critical role in East Asian polychrome artworks, yet their influence on coating properties remains insufficiently understood. In this study, three traditional animal glues—bone glue, hide glue, and fish glue—were systematically compared as binding media for cinnabar (red), orpiment (yellow), and lazurite (blue) coatings on pinewood substrates. FTIR spectra of all glues exhibited characteristic collagen-related absorption bands, with bone glue showing a stronger hydroxyl peak at 3280 cm⁻¹. Viscosity analysis revealed bone glue as the most stable, reaching 120 ± 6 mPa·s at 20% concentration, compared with lower values for fish glue and hide glue. Colorimetric analysis indicated that cinnabar coatings were primarily affected by glue concentration, while orpiment coatings showed significant glue-type effects on chroma, with hide glue producing the highest saturation. Lazurite coatings displayed the strongest adhesive-related differences: hide glue enhanced saturation, whereas fish glue increased lightness. Gloss remained consistently low (<3 Gloss Units (GUs)), in line with the matte appearance of historical coatings, although bone glue produced smoother cinnabar surfaces (Ra = 1.72 µm, GU = 3.09). Two-way ANOVA confirmed that both the glue type and concentration significantly influenced chroma, gloss, and roughness. These findings demonstrate that although all animal glues share a collagenous origin, their distinct physicochemical properties shape the optical and microstructural qualities of polychrome coatings, offering a scientific basis for adhesive selection in cultural heritage conservation. Full article

This study developed a waterborne UV-curable acrylic composite coating incorporated with carved lacquer powder and systematically investigated the effects of powder and deionized water content on its properties. The results showed that the carved lacquer powder content significantly influenced the optical, mechanical, and curing behaviors of the coating, while the water content had negligible impact. Specifically, increasing the powder content reduced lightness, enhanced red hue, and decreased gloss. An optimal comprehensive performance was achieved at 20% powder content, with adhesion reaching grade 5, flexibility of 10 mm, and impact resistance of 6 kg·cm. FTIR analysis confirmed that high powder content (≥20%) led to incomplete curing due to UV shielding. The coatings showed moderate resistance to water, acid, and saline environments but poor alkaline resistance due to the chemical instability of cinnabar. SEM revealed increased surface roughness at high powder loading (30%). More importantly, this work presents a sustainable approach to recycle carved lacquer waste and demonstrates a viable strategy for incorporating traditional cultural heritage materials into advanced functional coatings. The study demonstrates that carved lacquer powder can be effectively integrated into UV-curable coatings to achieve unique decorative effects, and a content of approximately 20% is recommended to achieve balanced properties. Full article

Chinese lacquer (urushi), a traditional East Asian coating material, has been used for more than 7000 years due to its durability, gloss, and cultural significance. However, its long-term stability under natural light remains insufficiently studied, especially regarding the role of mineral pigments in modulating photoaging behavior. In this study, three traditional lacquer coatings pigmented with cinnabar (HgS), orpiment (As₂S₃), and lapis lazuli were subjected to natural light aging for nine weeks. Colorimetric analysis revealed rapid chromatic changes during the initial stage of exposure, followed by slower transformations, with cinnabar-based red lacquer showing superior stability compared to orpiment- and lapis-based coatings. Gloss measurements and surface roughness analyses demonstrated a strong negative correlation, with yellow lacquer exhibiting the most severe gloss loss (≈30%) and roughness increase (≈89%), consistent with scanning electron microscopy observations of microcracking and surface deterioration. Fourier-transform infrared spectroscopy (FTIR) indicated pigment-dependent oxidative degradation, characterized by intensified carbonyl and aromatic C=C bands. Collectively, the results confirm that mineral pigments strongly influence the optical, chemical, and structural stability of lacquer coatings. From a conservation perspective, cinnabar-based lacquers exhibit higher resilience, whereas orpiment- and lapis-colored coatings are highly vulnerable, underscoring the need for pigment-specific preservation strategies for lacquerware cultural heritage. Full article

Two gold-decorated wooden sculptures of Qing Dynasty collected in Qianjiang Cultural Administration Institute, Chongqing, China, holds significant cultural value. Although in appearance they were preserved completely, the wooden bodies exhibited a certain degree of decay with severe peeling of the surface painted layer and gold lacquer layer. In this study, the samples from the sculptures were characterized by microscopy, SED–EDS (Scanning Electron Microscopy and Energy Dispersive Spectrometer) analysis, and Raman spectroscopy, while the preservation state of wooden core was assessed through the fluorescence microscopy and NREL (National Renewable Energy Laboratory) chemical analysis methods. Findings reveal that the raw material for wooden sculpture is cypress, and holocellulose content of wooden core is as low as 32%. The raw materials for red pigment include cinnabar (HgS) and hematite (Fe₂O₃). There are multiple layers of lacquer and gold can be observed. There is a layer made of clay, gypsum, or brick ash beneath the lacquer layer and colored layer. The gold layer on the surface adopted traditional Chinese gilding technique which is called sticking gold. This study provides insights into the material properties and technological features of these wooden sculptures, offering a reference for future protection of similar sculptures. Full article

The Chengyang City (城阳城) site in Xinyang, Henan Province, China, was a significant northern military stronghold of the Chu state during the Warring States period (475/403–221 BCE). The lacquered armor unearthed from Tomb M18 provides critical material evidence for studying ancient military technology and lacquer craftsmanship. In this study, a comprehensive analytical approach combining ultra-depth optical microscopy, Fourier-transform infrared spectroscopy (FTIR), confocal micro-Raman spectroscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) and pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) were employed to systematically characterize the structural and compositional features of the armor samples. The results indicate that the armor was constructed with a leather substrate and lacked any lacquer ash layer, while the surface exhibited multiple layers of mixed laccol and urushiol-based lacquer coatings. Cinnabar (HgS) was identified as the primary red pigment, and no carbon black or iron-based blackening agents were detected in the dark lacquer layers. Notably, the presence of laccol suggests that such lacquer resources may have also been produced in mainland China, offering new perspectives on the prevailing view that associates laccol exclusively with “Vietnamese lacquer.” This study elucidates the technological characteristics of mid-Warring States period lacquered armor, provides scientific insights into ancient lacquering techniques, and contributes valuable data for the conservation and restoration of similar cultural heritage artifacts. Full article

This paper focuses on the study of the arena wall decoration in the amphitheater at the archaeological site of Viminacium. The architectural characteristics of the amphitheater, along with the spectacle iconography, have made this finding one of the most interesting discoveries at Viminacium, as well as in a wider context. A multidisciplinary approach that included an iconographic and archaeological study, as well as Energy Dispersive X-ray Fluorescence (EDXRF), X-ray Powder Diffraction (XRD), and Raman and Fourier-transform Infrared (FTIR) spectroscopy analysis, was applied to determine the palette of the pigments used for the arena wall decoration and understand the iconography and its context in more detail. Among the commonly used earth pigments (yellow, red, brown, and green colors), copper-based pigments (green and blue Egyptian blue), and the most precious ones for the period—namely, cinnabar and lapis lazuli—were identified. The applied analytical techniques enabled a tentative suggestion of the origin of the raw materials of some of the pigments that were used, such as marine sediments or rocks from different destinations. Due to the fact that the Viminacium amphitheater constitutes a typical example of a provincial building reserved for public spectacles, the results of this study will significantly contribute to our understanding of the function of the amphitheaters in the Danubian region, as well as throughout the Roman world. Full article

Mining activity in Peru generates environmental liabilities with the potential to release toxic metals into the environment. This study conducted a comprehensive physical, chemical, mineralogical, and toxicological characterization of ten active and inactive tailings samples from the Arequipa region in southern Peru. Particle size distribution analysis, inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and the Toxicity Characteristic Leaching Procedure (TCLP) followed by ICP-MS were employed. The results revealed variable particle size distributions, with the sample of Secocha exhibiting the finest granulometry. Chemically, 8 out of 10 samples exhibited concentrations of at least two metals surpassing the Peruvian Environmental Quality Standards (EQS) for soils with values reaching >6000 mg/kg of arsenic (Paraiso), 193.1 mg/kg of mercury (Mollehuaca), and 2309 mg/kg of zinc (Paraiso). Mineralogical analysis revealed the presence of sulfides such as arsenopyrite, cinnabar, galena, and sphalerite, along with uraninite in the Otapara sample. In the TCLP tests, 5 out of 10 samples released at least two metals exceeding the environmental standards on water quality, with concentrations up to 0.401 mg/L for mercury (Paraiso), 0.590 mg/L for lead (Paraiso), and 9.286 mg/L for zinc (Kiowa Cobre). These results demonstrate elevated levels of Potentially Toxic Elements (PTEs) in both solid and dissolved states, reflecting a critical geochemical risk in the evaluated areas. Full article

Mineral characterization of gold-bearing metasomatites in the Khaptasynnakh ore zone of the Anabar Shield is provided in detail. The following ore formation sequence of mineral associations in the Khaptasynnakh zone was found: pyrite and pyrrhotite → gersdorffite and molybdenite → chalcopyrite, sphalerite, and galena → bornite and chalcocite → tellurides, native gold, stibnite, cinnabar, and native bismuth. Native gold is characterized by varying fineness (550 to 926‰) and Cu impurity (up to 7.87%) values. Most often, it forms symplectite intergrowths with Au telluride–calaverite. Native gold and Au tellurides showed inclusions of chalcocite, bornite, altaite, tellurobismuthite, rickardite, petzite, and clausthalite. A two-stage formation process of the examined gold is suggested: Low-fineness gold was introduced into the system during early potassium metasomatism, while higher-fineness gold related to silica metasomatism resulted from its additional mobilization by fluid during late-stage formation. The low-temperature gold–telluride association observed in the mineral paragenesis of ore-bearing rocks, as well as its inclusions in native gold, suggests epithermal gold–telluride mineralization. Mineral inclusions examined in placer gold validate a genetic relation between the examined ores and gold placers in the Khaptasynnakh ore zone. Full article

This study analyzes a lacquered ear cup excavated from the Luobowan tomb complex in Guigang, Guangxi, attributed to the Nanyue Kingdom of the early Han dynasty. A range of analytical techniques, including optical microscopy (OM), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), pyrolysis–gas chromatography–mass spectrometry (Py-GC-MS), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD), were employed to investigate the structural layers, material composition, and preservation state of the artifact. The lacquerware consists of four traditional layers: a wooden core, fabric reinforcement, lacquer ground, and lacquer film, reflecting Central Plains lacquerware techniques. The wooden core was identified as Phoebe sp., and the fabric layer is likely hemp, though fiber degradation limited exact identification. The lacquer ground layer contains natural lacquer mixed with SiO₂ from brick or tile powder. The lacquer film is a blend of Chinese and Vietnamese lacquer, with no synthetic additives or plant oils detected. The red lacquer layer contains cinnabar (HgS) as a pigment, while the black lacquer uses carbon black. Differences in moisture content between the red and black lacquer films are attributed to variations in surface porosity and pigment characteristics. This research provides valuable insights into Nanyue lacquer technology and preservation challenges. Full article

The colour degradation of murals presents a significant challenge in the conservation of architectural heritage. Previous research has often concentrated on localized pigment changes while paying insufficient attention to the interaction between colour variation and indoor environmental conditions. Although non-destructive analytical techniques are widely used in heritage studies, their integrated application in combination with colourimetry has been limited, particularly in the context of Tibetan Buddhist murals in highland continental climates. This study investigates the murals of Liuli Hall in Meidai Lamasery, Inner Mongolia, as a representative case. We employed a comprehensive methodology that combines non-destructive analytical tools, gas chromatography–mass spectrometry, and quantitative colour analysis to examine pigment composition, binding material, and surface deterioration. Through joint analysis using the CIE Lab and CIE LCh colour space systems, we quantified mural colour changes and explored their correlation with material degradation and environmental exposure. The pigments identified include cinnabar, atacamite, azurite, and chalk, with animal glue and drying oils as binding materials. Colourimetric results revealed pronounced yellowing on the east and west walls, primarily caused by the ageing of organic binders. In contrast, a notable reduction in brightness on the south wall was attributed to dust accumulation. These findings support tailored conservation measures such as regular surface cleaning for the south wall and antioxidant stabilization treatments for the east and west walls. Initial cleaning efforts proved effective. The integrated approach adopted in this study provides a replicable model for mural diagnostics and conservation under complex environmental conditions. Full article

This study presents the first scientific characterization of the white preparatory layer and polychrome pigments on painted wooden figurines excavated from the Mawangdui Tomb No. 1, dating to the Han dynasty. A combination of analytical techniques, including XRF mapping, SEM, ATR-FTIR, XRD, and Raman spectroscopy, was used to investigate the composition, structure, and potential additives in the white layer. The results reveal that the preparatory layer is primarily composed of gypsum (CaSO₄·2H₂O) and calcite (CaCO₃), with minor phases such as anhydrite and larnite. SEM observations show a porous microstructure of needle-like crystals, while spectroscopic data suggest possible traces of organic binders. The preparatory layer was likely applied to smooth surface irregularities and support polychrome decoration, such as cinnabar and carbon-based pigments, and may have also functioned as a putty in localized areas. This represents the first confirmed use of gypsum-based plaster in ancient Chinese woodcarving, showing unexpected parallels with surface preparation techniques used in New Kingdom Egypt. However, the presence of organic additives and the internal structure of the figurines remain unresolved due to equipment limitations. These findings provide new insights into ancient material practices and highlight the importance of environmental control and material-specific conservation strategies for fragile gypsum-based heritage objects. Full article

The existence of historical pigments databases is important to speed up cultural heritage research. Knowledge of their chemical composition and their manufacture contributes to the study of art history and helps develop accurate conservation-restoration strategies. In this study, a total of nineteen pigments, among which we find silicates (Egyptian blue, natural and synthetic blue ultramarine, green earth and chrysocolla), oxides (natural and synthetic hematite, red and yellow natural ochres, and chromium green), carbonates (natural and synthetic azurite, natural and synthetic malachite, and white lead), sulphides (natural and synthetic cinnabar, and orpiment) and acetates, (verdigris) have been characterized by Fourier Transform Infrared-Spectroscopy in Attenuated Total Reflection (ATR-FTIR) and Diffuse Reflectance (DRIFT) modalities. Considering the latter, there is still a great deal of uncertainty in the interpretation of the different IR vibrational bands. Therefore, a comparative study between these two techniques has been carried out to highlight the potential of DRIFT spectroscopy as a portable and non-destructive technique that allows the differentiation and characterization of historical pigments in the field of cultural heritage. Before performing FTIR analysis, pigments were analysed using X-ray diffraction (XRD) to detect impurities and/or additives in the pigments. Differentiation between natural and synthetic pigments was possible due to the identification of impurities in natural pigments, and manufacture-related compounds or additives in synthetic pigments. Results obtained in this study have proven DRIFT to be a very useful analytical technique for in situ characterization of heritage materials. This study serves as an initial step in clarifying the challenges and uncertainties associated with interpreting spectra obtained through the DRIFT modality. However, the use of other complementary analytical techniques is required. Full article