Search Results (449)

Historical buildings are highly prone to degradation because they are continuously exposed to the external environment, which represents an extremely aggressive factor. Globally, there are so many historical buildings that need urgent restoration. This paper focuses on finding a new consolidant for real oak old wood and presents a new recipe based on multi-walled carbon nanotubes (MWCNTs) decorated with zinc oxide (ZnO) nanoparticles dispersed in PHBHV solution, aimed at improving old wood properties. The research was conducted on Banloc Castle oak wood, which is predominant throughout the castle. The obtained treatment was applied by brushing onto the wood surface, while the retention and uniform application of the consolidation were confirmed by optical microscopy. One major advantage of the treatment is that the natural color of the wood is not affected, with the total color difference being very small. Another advantage gained after consolidation was the enhanced hydrophobic behavior of the old wood confirmed through water absorption, humidity and contact angle tests. In contrast, untreated wood exhibited hydrophilic behavior and high water and moisture absorption capacity, making aged wood extremely vulnerable to environmental degradation over time. Mechanical tests confirmed that the consolidant solution significantly improved the properties of the wooden material, due to the effective impregnation of the treatment into the wood structure. Furthermore, the MWCNT-based consolidant inhibited the growth of the Aspergillus niger strain, providing antifungal protection and preventing the colonization of microorganisms within the wood structure and its subsequent degradation. Through the methods investigated in this work, it was proven that the treatment is suitable for the consolidation of aged and degraded oak wood materials. Full article

Novel biobased materials and processing techniques are actively developed for sustainable coatings. This study investigated the potential mutagenicity of novel materials and derived dispersions used for biobased paper and wood coatings using a pilot 384-well test. The standard Ames test was performed for selected materials to compare and validate the results with the non-standard 384-well test. Salmonella Typhimurium strains (TA100 and TA98) were used for testing. Experimental dispersions were prepared using suberin and betulin extracted from outer birch bark. The test set of seven samples (n = 7) included commercial reference samples and additives. Both test methods were suitable for these samples but also highlighted method-specific differences and challenges. For suberin-derived materials and betulin at 0.5–1% concentration, neither of the tests indicated mutagenicity. In the case of some industrial samples, the 384-well test and the standard Ames test gave clearly contradictory results. These can be explained by the test limitations, such as the sample color or compositional instability of dispersions. To summarize, this study indicated the need to test the novel coating materials with multiple concentrations, and several bacterial strains carrying different types of genetic mutations, as well as to use complementary genotoxicity tests for a more accurate toxicity profile. Full article

This study examines the physical and mechanical properties of pedunculate oak (Quercus robur L.) wood samples taken from historical trabaccolo ship Carmen during restoration. The research is based on a methodological approach typical of conservation–restoration practice, in which only a limited number of samples can be taken to preserve the authenticity and integrity of the original material. Two groups of samples were analyzed visually: preserved (bright) wood and wood showing cross-sectional discoloration (dark). Physical properties (color, moisture content, density, porosity and swelling) and mechanical properties (compressive strength, bending strength and modulus of elasticity) were determined according to relevant ISO standards and chemical changes in the wood structure (FT-IR). FT-IR analysis revealed progressive degradation of hemicelluloses and oxidative modification of lignin, which was particularly significant in dark wood samples. The results of tests of physical properties indicate that dark samples exhibit higher moisture content (13%), lower density (about 7%) and greater porosity compared to preserved samples (bright wood). The compressive strength of the bright specimens was 38.3% higher than that of the dark specimens, suggesting reduced mechanical performance of the altered wood. The bending strength and modulus of elasticity of the preserved samples (bright wood) corresponded to literature data for recent oak wood. Full article

Wood coatings play a critical role in protecting wood substrates from environmental degradation, particularly ultraviolet (UV)-induced photodegradation. This review comprehensively examines the mechanisms of wood coating photodegradation, the factors influencing their durability, and current anti-aging strategies. Photodegradation arises from polymer chain scission, chemical structure reorganization, and photo-oxidation of lignin and cellulose, leading to coating chalking, cracking, gloss loss, and color changes, ultimately compromising wood mechanical properties and service life. Key anti-aging strategies include UV absorbers, which convert harmful UV radiation into heat; hindered amine light stabilizers (HALSs) that capture free radicals and quench excited-state molecules; barrier and shielding materials that form dense physical or nanostructured networks to block UV penetration and enhance mechanical and water resistance; and antioxidants that neutralize free radicals or decompose peroxides at the molecular level. Each approach can be employed individually or synergistically to enhance coating durability. Challenges remain in achieving long-term outdoor stability, balancing transparency and UV shielding, optimizing nanoparticle dispersion, and maintaining the activity of natural antioxidants. Future research should focus on multifunctional composite coatings integrating bio-based materials and nanotechnology, smart responsive systems, adaptive protection mechanisms, and standardized long-term evaluation protocols. These advancements will facilitate the development of high-performance, sustainable wood coatings and promote the value-added utilization of wood resources. Full article

This work analyses the influence of hydrothermal treatment (steaming) on the color stability and photochemical degradation of beech wood (Fagus sylvatica L.) with false heartwood under the influence of UV radiation. Samples in the native state and after steaming at temperatures of 105 °C (Mode I) and 120 °C (Mode II) were exposed to simulated aging in a Xenotest device for 360 h. Color changes were assessed in the color space CIE L*a*b* and surface chemical changes using ATR-FTIR spectroscopy. The results showed that unsteamed wood darkens significantly under the influence of UV radiation (ΔL* = −10.2), while wood steamed at 120 °C shows the opposite trend—lightening (ΔL* = +8.8). The color difference ΔE* reached values of 12 to 16 units for unsteamed wood, which indicates a complete color change. Steaming at higher temperatures successfully homogenizes the color of the sapwood and false heartwood and ensures their subsequent uniform visual aging. Full article

In healthy wood, color variations can betray structural changes that substantially affect the quality of the raw material. In the case of silver fir (Abies alba), compression wood is a very common structural anomaly. The material used for this study originates from centenary trees and serves to verify how the color of the wood responds to structural changes caused by the formation of compression wood. The color changes were tracked in the CIELab color space for different types of wood structures, such as normal wood, mild, moderate and severe compression wood. They occur in all directions of the wood, under the influence of compression stress and the cambium age, and they are discussed in relation to fluctuations in chemical composition at the tree level. Results of this study revealed that the color redness and yellowness react promptly to structural changes, and reveal the intensity levels of compression wood (mild, moderate, and severe). It was noticed that lightness is slightly sensitive to the onset of compression wood. Clear trends in wood color change along the trees were observed. The chromatic specificity of compression wood and its relationship with the environment could allow historical reconstruction and monitoring of tree life conditions through wood color. Full article

The influence of growing site conditions on the chromatic properties of heartwood in black locust (Robinia pseudoacacia L.) cultivar ‘Nyírségi’ sampled from five regions of Hungary was investigated in this study. A total of 23 boards (average age of trees: 34.5 years) representing four site types were analyzed by instrumental colorimetry using the CIE Lab system. The overall average color coordinates were L* = 69.9 ± 4.0, a* = 4.0 ± 0.8, and b* = 27.4 ± 2.3. Significant chromatic differences were observed among site types proven by statistical analysis; however, no single site type consistently increased within-site color variability. Average total color differences (ΔE*) ranged from 3.94 to 6.31 across site types, corresponding to “noticeable” to “large” visual differences. Regionally, 89.1% of 55 specimen pairs exhibited clearly perceptible color variation (ΔE* > 2), with 61.8% classified as “large” (ΔE* > 5). Within-tree comparisons revealed ΔE* values of 3.72–3.75 under poor site conditions but <2.0 on good growing sites. The a* and b* components appear with measurable variations across all sites, while the characteristic yellow hue remains distinct and stable independent of site origin due to the high b* value. Full article

This study was carried out to investigate the antimicrobial performance and color stability of silver (Ag)-modified polyurethane and waterborne coating systems applied to Oriental beech (Fagus orientalis L.) wood after the specimens were subjected to UV aging for 24 h. Antimicrobial activity and color stability were evaluated before and after aging against Escherichia coli (E. coli, ATCC 25922), Staphylococcus aureus (S. aureus, NCTC 13552), and Candida albicans (C. albicans) in accordance with the JIS Z 2801 standard. Color changes were determined using CIELab parameters (ΔL*, Δa*, Δb*, and ΔE*) in accordance with the TS EN ISO 16474-3 standard. Prior to UV exposure, the highest antibacterial activity against E. coli occurred in Ag-modified waterborne varnish coatings, whereas the highest antifungal activity against C. albicans occurred in Ag-modified polyurethane paint systems. After UV aging, antimicrobial performance varied depending on the coating type. Particularly, Ag-modified waterborne varnish coatings retained significant antibacterial activity against E. coli and S. aureus and exhibited the highest antifungal performance against C. albicans. Color analysis revealed that UV exposure also caused significant changes in all coating systems. The most pronounced variations were observed for the lightness difference (ΔL*), red–green color difference (Δa*), and yellow–blue color difference (Δb*) parameters, while the lowest total color difference (ΔE*) values were observed for Ag-modified polyurethane and Ag-modified waterborne varnish coatings. Overall, Ag-modified waterborne varnish systems demonstrated superior performance in both antimicrobial activity and color stability after UV aging. Full article

Glued-laminated timber (GLT) and cross-laminated timber (CLT) panels are increasingly used as exposed structural elements in representative buildings. These structures are often part of public-use areas, which require the application of restrictive fire-safety measures without significantly affecting the color of exposed wooden surfaces during the service life of these building elements. The effect of fire-retardant treatments on the color of Scots pine (Pinus sylvestris L.) wood was evaluated using five impregnation agents with different active substances. Changes in gloss and color characteristics—lightness (L*), green-red coordinate (a*), and blue-and-yellow coordinate (b*)—were measured sequentially directly after impregnation, after exposure to variable humidity conditions and after exposure to UV radiation. The total color difference (ΔE*) ranged from 2.82 to 17.76 after impregnation and increased to 6.31–20.71 after aging, indicating a risk of aesthetic deterioration of fire-retardant-treated wood surfaces under typical service conditions for timber structures in representative buildings. The most pronounced color changes were observed for the fire retardant containing potassium and copper compounds (FR4) and the combination of 2-aminoethanol with boric acid (FR5). Full article

Color vision plays a critical role in Diptera behavior, particularly in the detection of oviposition sites. Necrophagous Diptera, like the Calliphoridae, are of forensic importance because the larvae are commonly used to estimate minimum postmortem intervals of human remains. To better understand which species are present, flies are routinely sampled in different habitats using baited traps; however, the influence of trap color on capture efficiency remains poorly understood. In this study, baited bottle traps painted clear, blue, red, and yellow were deployed in wooded habitats to collect adult dipterans. Overall captures were dominated by Lucilia coeruleiviridis (Diptera: Calliphoridae). Clear traps consistently captured a greater diversity of Calliphoridae, Muscidae, and Sarcophagidae. In contrast, yellow traps captured the fewest individuals overall, while red and blue traps yielded intermediate numbers. Dipteran composition in red and yellow traps, however, differed from those in clear traps. Collectively, these results indicate that clear baited traps are more effective for sampling adult necrophagous Diptera, whereas yellow baited traps may be less suitable. Additional investigation is warranted to characterize the complex interactions between visual and olfactory cues underlying attraction and oviposition site selection in necrophagous dipterans. Full article

Wood is a versatile material; however, it is susceptible to changes when exposed to extreme temperatures. This study investigated the physical, chemical, and mechanical properties of raulí (Nothofagus alpina) under different thermal stress conditions. The results showed that the moisture content at temperatures below 5 °C exhibited a significant reduction from 9.7% to 7.5% within the first 20 days. Conversely, under extreme cold (−20 °C), significant changes only occurred after 60 days, with an increase from 9.7% to 11%. At higher temperatures (50 °C, 95 °C, and 120 °C), moisture content dropped sharply after 40 days, nearing 0%. Additionally, analysis showed minor color changes in samples at low temperatures: RW2 (20 d; 5 °C, ΔE* = 3.46) and RW7 (40 d; 5 °C, ΔE* = 0.61); however, color changes were observed at higher temperatures (95–120 °C). RW15 (60 d; 120 °C, ΔE* = 37.16), indicating the degradation of cell wall polymers. Mechanical testing using three-point bending demonstrated that controlled heat treatments can improve the modulus of elasticity (MOE), modulus of rupture (MOR), and fracture energy. The most significant improvements were obtained at 120 °C for 60 days, with increases in MOE, MOR, and fracture energy of 22%, 60%, and 118%, respectively, compared to untreated wood. Full article

Spent coffee grounds (SCGs) and lignin-derived binders, such as ammonium lignosulfonate (ALS), are increasingly being explored as renewable resources to reduce reliance on conventional formaldehyde-based resins in wood-fiber biocomposites. Although prior work has shown that SCG–ALS adhesive systems can achieve promising mechanical performance, two practical aspects essential for industrial applications and circular design remain insufficiently explored: a predictable and reproducible visual appearance and credible end-of-life options. In this study, sustainable wood-fiber biocomposites bonded with SCG and ALS were assessed from an aesthetic performance and end-of-life perspective. Color was quantified in the CIE L*a*b* (CIELAB) space and expressed as total color difference (ΔE*) relative to a reference panel. Increasing total SCG + ALS content from 40 to 75 wt.% based on oven-dry fibers produced pronounced darkening, with lightness decreasing from L* = 47.1 to 34.3 and ΔE* increasing from 18.38 to 32.51. Short-term composting behavior was explored by embedding fragments from formulations with 40–60 wt.% total SCG + ALS (based on oven-dry fibers; equal SCG/ALS shares) into a mixed organic substrate adjusted to an initial C/N ≈ 30 and monitored for 30 days in pots and trays. The process remained predominantly mesophilic (≈14–22 °C); nevertheless, visible microbial colonization and progressive surface degradation were observed, indicating susceptibility to biological activity under moist, nutrient-rich conditions. Overall, the results show that SCG–ALS content strongly governs the visual identity of the biocomposites and suggest composting-oriented routes as a potential end-of-life direction at an exploratory level, while highlighting the need for standardized compostability assessment and longer-term monitoring to substantiate circularity claims. Full article

The textile industry is seeking alternative coloration methods to comply with the global demands for eco-friendly and non-hazardous dyes, as synthetic colorants are costly and substantially toxic in nature, having deleterious effects on the environment as well as ecosystems. This research aimed to develop a printed functional cotton fabric using a new bio-based pigment from acacia wood waste (Acacia nilotica) charcoal. Acacia charcoal was ground into fine powder and added into pigment paste with polyacrylic binder and screen printed on cotton fabric, followed by drying and curing. The printed fabric was tested for color strength (K/S), colorfastness, flame resistance, contact angle (for checking the hydrophobicity), thermal insulation, and tensile strength following standard testing protocols. Using different charcoal concentrations (in the range of 0.5–5%), the samples presented light to dark gray color and the K/S value gradually increased from 1.85 (0.5%) to 12.31 (5%), demonstrating stronger color depth. The printed fabrics revealed good results in terms of color fastness ratings (washing 3–5, dry rubbing 3–5, wet rubbing 3–5), satisfactory flame resistance, good thermal insulation, and excellent hydrophobicity. The obtained results contribute to sustainable and durable textile development for achieving better performance. Full article

A novel composite adhesive for lacquer film restoration was developed by modifying natural lacquer with Tween-20, soy protein isolate (SPI), and nano-SiO₂ to address the bonding failure and interfacial instability of glyoxal-dehydrated lacquerware. The optimal formulation (70% lacquer, 10% Tween-20, 15% SPI, 5% nano-SiO₂) achieved a shear bond strength of 3.8 ± 0.3 MPa, corresponding to a 58% increase compared with pure lacquer (2.4 ± 0.2 MPa). After 30 days of immersion in a pH 4.0 acidic solution, the adhesive retained 91 ± 3% of its initial shear strength, significantly higher than that of pure lacquer (65 ± 5%). Under accelerated aging conditions (50 °C and 95% relative humidity), the composite adhesive exhibited minimal weight gain (1.0 ± 0.2%) and no visible mold growth, whereas pure lacquer showed greater moisture uptake (3.0 ± 0.4%) accompanied by evident fungal colonization. The cured film displayed good color compatibility (ΔE ≈ 2.0) and improved flexibility (elongation at break: 12.5% vs. 4.2%). XPS and FTIR analyses suggested enhanced interfacial bonding through hydrogen-bond interactions and possible Si–O–C linkages at the wood–lacquer interface. Practical restoration of a Warring States period lacquer ear cup (China) demonstrated effective and stable reattachment of detached fragments with satisfactory visual integration and long-term durability. Overall, this work provides a compatible and durable material strategy for the conservation of glyoxal-dehydrated lacquerware. Full article

The antifungal properties of wood are often attributed to extractives that differ between heartwood and sapwood; however, quantitative evaluation methods remain limited. In this study, we investigated differences in fungal susceptibility between heartwood and sapwood of Aomori Hiba (Thujopsis dolabrata var. hondae) using solvent extraction, fungal growth inhibition assays, and digital image analysis. Heartwood and sapwood were distinguished based on anatomical characteristics and color, and extractives were obtained using ethanol as the solvent. Antifungal activity was evaluated against Aspergillus oryzae by monitoring fungal growth on culture media. Quantitative image analysis was applied to grayscale images to assess fungal growth inhibition, enabling objective comparison between samples. The results demonstrated that heartwood extracts consistently exhibited stronger fungal growth inhibition than sapwood extracts, which correlated with higher extractive contents. Image-derived metrics effectively captured differences in fungal growth that were not readily discernible by visual inspection alone. These findings demonstrate that digital image analysis can be effectively integrated with fungal susceptibility assays and extractive measurements to provide a practical framework for preliminary screening of antifungal potential in wood-derived materials. Full article