Search Results (15)

This paper provides a systematic review of urushiol-based antibacterial coatings for lacquer art applications, focusing on three key dimensions: molecular mechanisms, durability, and safety. Natural lacquer films form a dense three-dimensional network through laccase-catalyzed oxidative cross-linking, endowing them with excellent mechanical properties and corrosion resistance, while the catechol structure in urushiol confers broad-spectrum antibacterial potential. The article elaborates on the synergistic antibacterial mechanisms of urushiol, including covalent reactions with bacterial proteins via quinone intermediates, induction of oxidative stress, and metal ion chelation. It also reveals the dynamic change pattern of coating antibacterial activity over time, characterized by “high initial efficiency- gradual mid-term decline—long-term stabilization,” a process influenced collectively by side-chain unsaturation, degree of curing, and environmental factors such as temperature, humidity, and light exposure. From an application perspective, this review examines modification approaches such as silver/titanium dioxide composite systems, structurally regulated sustained-release strategies, and anti-adhesion surface designs, while pointing out current limitations in artistic compatibility, long-term durability, and safety assessment. Particularly in scenarios involving food contact and cultural heritage preservation, migration risks from unreacted urushiol monomers and metal nanoparticles, as well as the inherent sensitization potential of urushiol, remain critical challenges for safe application. Accordingly, this paper proposes the establishment of a holistic research framework covering “material design–process control–performance evaluation” and advocates for the development of functional coating systems with low migration, high biocompatibility, and preserved aesthetic value. Such advances are essential to promote the sustainable development and safe application of urushiol-based antibacterial coatings in fields such as cultural heritage conservation, daily-use utensils, and high-end decorative arts. Full article

This study systematically investigates the influence of 3D printing parameters on the surface morphology and coating performance of polylactic acid (PLA) substrates finished with traditional Chinese lacquer. PLA specimens were fabricated using fused deposition modeling (FDM) with varying print speeds, layer heights, and infill densities, followed by natural lacquer coating and controlled curing. Surface roughness, gloss, adhesion, and wear resistance were evaluated through standardized tests, while microstructural analysis using SEM revealed the interfacial morphology and film uniformity. Results indicate that layer height is the most dominant factor, exerting significant effects on all surface and coating properties. Increasing layer height led to higher surface roughness, which in turn reduced gloss due to enhanced diffuse scattering but improved adhesion and wear resistance through stronger mechanical interlocking. Print speed showed a secondary influence on adhesion, attributed to its effect on interlayer bonding and surface porosity, while infill density exhibited minimal influence except on wear resistance. The application of Chinese lacquer significantly reduced surface irregularities owing to its excellent self-leveling and gap-filling capabilities, producing smooth, durable, and well-adhered coatings. Overall, the study demonstrates that integrating traditional lacquer with modern FDM technology provides a sustainable and high-performance finishing solution for 3D-printed PLA, bridging cultural craftsmanship with advanced additive manufacturing for potential applications in decorative, protective, and eco-friendly products. Full article

Chinese lacquer, a historically significant bio-based coating, has garnered increasing attention in sustainable materials research due to its outstanding corrosion resistance, thermal stability, and environmental friendliness. Its curing process relies on the laccase-catalyzed oxidation and polymerization of urushiol to form a dense lacquer film. However, the stringent temperature and humidity requirements (20–30 °C, 70–80% humidity) and a curing period that can extend over several weeks severely constrain its industrial application. Recent studies have significantly enhanced the curing efficiency through strategies such as pre-polymerization control, metal ion catalysis (e.g., Cu²⁺ reducing drying time to just one day), and nanomaterial modification (e.g., nano-Al₂O₃ increasing film hardness to 6H). Nevertheless, challenges remain, including the sensitivity of laccase activity to environmental fluctuations, the trade-off between accelerated curing and film performance, and issues related to toxic pigments and VOC emissions. Future developments should integrate enzyme engineering (e.g., directed evolution to broaden laccase tolerance), intelligent catalytic systems (e.g., photo-enzyme synergy), and green technologies (e.g., UV curing), complemented by multiscale modeling and circular design strategies, to drive the innovative applications of Chinese lacquer in high-end fields such as aerospace sealing and cultural heritage preservation. Full article

This study systematically investigates the effects of repeated Kurome treatment—a physical modification method combining mechanical stirring and oxidative regulation—on the processing characteristics and film properties of Chinese lacquer (urushi). By subjecting raw lacquer to 1–4 cycles of hydration–dehydration (KL1–KL4), the researchers observed a significant increase in viscosity (from 12,688 to 16,468 mPa·s) and a dramatic reduction in curing time (from 74 h to just 3.6 h), driven by deep oxidation of urushiol and quinone-mediated crosslinking, as confirmed by FTIR spectroscopy. The Kurome treatment enabled controlled darkening (L* value decreased from 29.31 to 26.89) while maintaining stable hue and gloss (88.96–90.96 GU), with no adverse effects on abrasion resistance (mass loss of 0.126–0.150 g/100 r) or adhesion (9.58–9.75 MPa). The reduced transparency of the KL3/KL4 films is associated with a densified polymer network, a feature that may benefit protective coatings. Scanning electron microscopy (SEM) analysis confirmed the formation of uniform, defect-free surfaces across all treatment groups. Among them, the KL2 group (viscosity of 14,630 mPa·s, curing time of 9.2 h) exhibited the most favorable balance for industrial applications. This study establishes Kurome technology as a low-carbon, additive-free strategy that enhances the processability of Chinese lacquer while preserving its traditional craftsmanship standards, offering scientific support for its sustainable use in modern coatings and cultural heritage conservation. Full article

In addition to the mechanical properties and barrier performance, one of the key properties of flexible films used in food packaging is the resistance of their gas barrier layer to buckling and bending. Testing the gas barrier before and after mechanical stress is time-consuming and resource-intensive, but important to assure a certain gas barrier during the whole life time of the package until food consumption. The aim of this study was, on the one hand, to identify the most significant influencing factors of a composite lacquer formulation and coating on its buckling resistance and, on the other hand, to show a fast and efficient method to identify defects occurring during buckling. The influence of mechanical stress was simulated via Gelbo-Flex treatment, and the samples were examined and evaluated before and after using light microscopy. The evaluation was verified with scanning electron microscopy (SEM) and helium barrier measurement. Polyethylene terephthalate (PET) and polyethylene (PE) films were coated with composite barrier lacquers made of polyvinyl alcohol (PVA) and montmorillonite (MMT) and the wet coating layer thickness (20, 40, 80, and 130 μm) and the composition of the coating were changed. It was found that thin coatings are more resistant to buckling than thick coatings. It was also shown that a higher proportion of MMT in the coating layer leads to a better gas barrier, but poorer buckling resistance. Additionally, it was found that soft PE films are already subjected to high stresses during the coating process, which means that barrier coatings do not build up ideally. However, the barrier-coated soft film withstood mechanical stress better and lost less barrier by a lower factor than the counterpart on the basis of PET. To conclude, the evaluation of the buckling resistance with microscopy offers an efficient method during lacquer development; however, the final decision on the right lacquer composition is dependent on many factors. Full article

Raw lacquer, known for its superior performance as a natural liquid coating, boasts excellent physical and mechanical properties as well as durability, making it widely used in manufacturing. However, the high hardness of the lacquer film upon complete curing poses challenges for carving and mechanical engraving. Therefore, it is necessary to study the curing process of lacquer films to obtain films suitable for carving or mechanical engraving. This study involves the preparation of raw lacquer with varying amounts of tung oil added, followed by the measurement of film drying time, surface roughness, glossiness, hardness, and adhesion on substrates to determine the optimal drying conditions. Additionally, SEM analysis of the carved surfaces and FT-IR analysis were used to investigate the impact of tung oil addition on lacquer carving performance and its variation. The results indicate that tung oil, to a certain extent, contributes to a smoother lacquer film but adversely affects film hardness and adhesion to Prunus serotina. However, with an increase in the amount of refined tung oil to 15%, the film exhibits improved glossiness, smoother carving tool marks, and reduced debris, thereby validating the feasibility of mechanical carving of tung oil-modified raw lacquer to some extent. Full article

Untreated polyester films and fibers can be hardly printed or coated, in particular if aqueous inks or lacquers have to be applied. Therefore, an adequate primer layer has to be applied first. A cationic polymer formulation based on poly(dimethylamine-co-epichlorohydrin-co-ethylenediamine) (PDEHED) was used as primer layer for digital printing on polyester fabrics. Because of the exceedingly high requirements on the homogeneity of such layers, hyperspectral imaging was used for qualitative and quantitative monitoring of the distribution of the primer layer on the textiles. Multivariate data analysis methods based on the PLS algorithm were applied for quantification of the NIR reflection spectra using gravimetry as a reference method. Optimization of the calibration method resulted in various models with prediction errors of about 1.2 g/m². The prediction performance of the models was proven in external validations using independent samples. Moreover, a special ink jet printing technology was tested for application of the aqueous primer formulation itself. Since possible clogging of jet nozzles in the print head might lead to inhomogeneity in the coatings such as missing tracks, the potential of hyperspectral imaging to detect such defects was investigated. It was demonstrated that simulated missing tracks can be clearly detected. Consequently, hyperspectral imaging has been proven to be a powerful analytical tool for in-line monitoring of the quality of printability improvement layers and similar systems. Full article

In order to control the production cost of lacquer products, Cu–ethanolamine nanozymes were synthesized to simulate laccase to catalyze the oxidation and polymerization of urushiol. First-principles calculation results indicate that the D-band center of Cu center in the nanozymes was closer to the Fermi level than that of laccase, so Cu–ethanolamine was more conducive to the adsorption of substrate. The activation energy of Cu-ethanolamine catalyzed the oxidation of urushiol was significantly lower than that of laccase. Therefore, we inferred that the synthesized Cu–ethanolamine had a better catalytic effect on urushiol and was more conducive to paint film drying. By comprehensive comparison, the drying characteristics of the Cu–ethanolamine and raw lacquer with a 1:20 ratio are found to be closest to those of the raw lacquer, and the drying time is significantly shortened. The reaction results of the drying process performance test on the sample indicate that the composite lacquer can achieve the market-desired effect and performance requirements of the paint process. Full article

The fungal disease of the nail, onychomycosis, which is also the most prevalent nail disturbance, demands effective topical treatment options considering the possible adverse effects of systemic antifungal therapy. The current work is focused on development of an adhesive and resistant, drug-delivering and permeation-enhancing polymeric film containing econazole nitrate (ECN) for topical antifungal treatment. The development of the lacquer formulation was guided by the Quality by Design approach to achieve the critical quality attributes needed to obtain the product of desired quality. Eudragit RSPO at 10% w/w was found to be the ideal adhesive polymer for the application and an optimal permeation-enhancing lacquer formulation was achieved by the optimization of other formulation excipients, such as plasticizer and the solvent system. Additionally, novel experimental enhancements introduced to the research included refined D₅₀ drying time and drying rate tests for lacquer characterization as well as a multi-mechanism permeation-enhancing pre-treatment. Moreover, a practical implication was provided by a handwashing simulation designed to test the performance of the lacquer during actual use. In vitro drug release testing and ex vivo nail permeation testing demonstrated that the optimized nail lacquer performed better than control lacquer lacking the permeation enhancer by achieving a faster and sustained delivery of ECN. It can be concluded that this is a promising drug delivery system for topical antifungal treatment of onychomycotic nails, and the novel characterization techniques may be adapted for similar formulations in the future. Full article

Whether modified poplar can obtain a qualified or even excellent finishing effect on European and American furniture is worthy of deep study. To evaluate whether the conventional non-transparent coating process is suitable for modified poplar, a multi-level hybrid orthogonal experiment method was carried out to start research on how factors affect the paint film performance of the non-transparent coating process. The effect of experimental factors and levels on paint film performance is pointed out, and the optimal factors and levels are found. Parameter optimization of the polyurethane non-transparent finishing process based on modified poplar is carried out. An application basis was provided for the extensive use of modified poplar wood as a substrate in the European and American furniture markets. The conclusions are: (1) gloss of paint film can be improved by increasing the number of nitrocellulose (NC) lacquer transparent topcoats, (2) adhesion and thickness of paint film can be improved by polyurethane (PU) sealing primer, (3) the initial paint film’s abrasion is influenced efficiently by the coating process and coating sanding. PU sealing primer has an efficient influence on the later abrasion of paint film. The effect of modified poplar surface pretreatment on the mass loss of paint film tends to be stable. Full article

In this study, a renewable polymeric material, refined oriental lacquer (ROL), used as a wood protective coating, and the Acacia confusa Merr. heartwood extractive, which was added as a natural photostabilizer for improving the lightfastness of ROL, were investigated. The best extract conditions for preparing heartwood extractives and the most suitable amount of addition (0, 1, 3, 5, and 10 phr) were investigated. The lightfastness index including brightness difference (ΔL *), yellowness difference (ΔYI), and color difference (ΔE *), and their applied properties of coating and film were measured. In the manufacture of heartwood extractives, the yield of extractives with acetone solvent was 9.2%, which was higher than that from toluene/ethanol solvent of 2.6%, and also had the most abundant total phenolic contents (535.2 mgGAE/g) and total flavonoid contents (252.3 μgRE/g). According to the SEM inspection and FTIR analysis, the plant gums migration to the surface of films and cracks occurred after UV exposure. The phenomena for photodegradation of ROL films were reduced after the addition of heartwood extractives. Among the different amounts of the heartwood extractives, the 10 phr addition was the best choice; however, the 1 phr heartwood extractive addition already showed noticeable lightfastness improvement. The drying times of ROL were extended and film performances worse with higher additions of heartwood extractives. Among the ROL films with different heartwood extractive additions, the ROL film with 1 phr addition had superior films properties, regarding adhesion and thermal stability, compared with the films of raw oriental lacquer. Full article

Refined oriental lacquer (ROL) is a natural polymeric material with a satiny texture, elegant beauty, and high durability for wood furniture and handicraft finishing. However, its poor lightfastness, which results from the photo-degradation or photo-oxidation of its main component, catechol derivatives, must be improved for its widespread utilization. In this study, two experiments were performed. First, five types of antioxidants, including three primary antioxidants, such as 2,2′-methylenebis(6-nonyl-p-cresol) (coded as AO-1), 2,2′-methylenebis(6-tert-butyl-4-methylphenol) (AO-2), and bis [4-(2-phenyl-2-propyl) phenyl] amine (AO-N), and two secondary antioxidants, such as tris (2,4-ditert-butylphenyl) phosphite (AO-P) and dilauryl thiodipropionate (AO-S), were investigated to determine which is the most effective for improving the lightfastness of ROL. Secondly, the appropriate quantity of the best antioxidant, including 0, 1, 2, 3, 5, and 10 phr, was also determined. The lightfastness parameters, such as brightness difference (ΔL*), yellowness difference (ΔYI), and color difference (ΔE*), as well as other coating and film properties, were assessed. The results showed that the primary antioxidants had higher efficiency than secondary antioxidants for improving the lightfastness of ROL. Among the primary antioxidants, the 5 phr AO-N was the most effective at improving the lightfastness of ROL; however, 1 phr addition had already shown significantly improved efficiency. In addition, the drying time of ROL was extended and film properties decreased when increasing the content of AO-N, but the 1-phr-containing ROL displayed superior film properties, especially adhesion and bending resistance, compared with the raw ROL film. Full article

Asian lacquer is a special polymeric material tapped from lacquer trees. The tree’s sap is a complex mixture of compounds, such as catechol lipids, polysaccharides, glycoproteins, enzymes, and water. Researchers have not yet quantitatively analyzed blended lacquers. We evaluated the compositions of Japanese and Vietnamese lacquers, and blends of the two, using time-of-flight secondary ion mass spectrometry (ToF–SIMS), pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS), and high-performance liquid chromatography (HPLC). ToF–SIMS provided quantitative results for blended lacquers; provided structural information on polymeric lacquer films; and indicated the presence of dimers of urushiol–urushiol, urushiol–laccol, and laccol–laccol derivatives. We used Py–GC/MS and HPLC to obtain linear calibration curves. The specific peak intensity was a linear function of the ratio of Japanese to Vietnamese lacquer in the blends. For an unknown mixture, all three techniques gave essentially the same results. These quantitative methods will be useful for improving the physical properties of polymeric lacquer films, and evaluating the lacquer quality in industry and historic conservation. Full article

Self-cleaning and/or photocatalytic films on polymer substrates have found numerous applications during the past decades. However, the common demand for high-temperature post synthesis treatment limits the application to temperature resistant substrates only. Herein, we prepared self-cleaning photocatalytic films on four thermosensitive polymeric substrates: polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), and acryl coated polyester (PES) fabric (D2) with poly(vinylidene fluoride) (PVDF) containing lacquer (D1). TiO₂ was prepared via a low-temperature sol-gel process using titanium(IV) isopropoxide and zirconium(IV) butoxide as precursors with various loading levels of Zr; 0, 5, 10, and 20 mol.%, and deposited on the substrates by using a SiO₂ binder in form of thin films (ca. 200 nm thick) via dip-coating. The films were characterized by SEM, hardness test, UV-Vis, photothermal beam deflection spectroscopy, and IR spectroscopy, while photocatalytic activity was measured by the fluorescence-based method of the terephthalic acid probe and wetting by contact angle measurements. Films containing 10 mol.% of Zr showed the best compromise regarding photocatalytic activity and mechanical stability while from substrates point of view PVC performed the best, followed by PMMA, D1, and D2. The beneficial role of SiO₂ binder was not only guaranteeing excellent mechanical stability, but also to prevent the D1 polymer from deterioration; the latter was found to be labile to long-term solar-light exposure due to degradation of the top PVDF layer. Full article

Two kinds of aqueous acrylic polyols (single step and multi step synthesis type)have been investigated for their performance in the two-component aqueous polyurethaneapplication, by using more selective catalysts. The aliphatic polyfunctional isocyanatesbased on hexamethylen diisocyanates have been employed as suitable hardeners. Thecomplex of zirconium, commercially known as K-KAT^®XC-6212, and manganese (III)complexes with mixed ligands based on the derivative of maleic acid have been used ascatalysts in this study. Both of the aqueous polyols give good results, in terms of applicationand hardness, when elevated temperatures and more selective catalysts are applied. A moreselective catalyst promotes the reaction between the isocyanate and polyol component. Thisincreases the percentage of urethane bonds and the degree of hardness in the films formedfrom the two components of aqueous polyurethane lacquers. The polyol based on the singlestep synthesis route is favourable concerning potlife and hardness. The obtained resultsshow that the performance of the two-component aqueous polyurethane coatings depends onthe polymer structure of the polyols as well as on the selectivity of the employed catalyst. Full article