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This study aimed to investigate the effects of mineral impregnation on fir wood using magnesium-based compounds. Two methods, combination and separate treatment, were used to impregnate heat-treated and non-treated samples. The Bethel method, involving vacuum and pressure, was employed for the impregnation process. The impregnated samples underwent assessments for weight gain, volumetric bulking, water soaking tests, water droplet contact angle, mechanical properties, and fire resistance. Additionally, SEM and EDAX analyses were conducted to evaluate the changes in the wood structure pre- and post-impregnation. The findings revealed the filling of pores and cavities in certain areas with Sorel cement, particle accumulation in cell walls and cell lumina, and an increase in the presence of Mg, Cl, and O elements in the impregnated samples. Furthermore, the physical property analyses indicated improved wood properties post-impregnation, with the combination impregnation method demonstrating the most notable performance in terms of weight gain percentage. Electron microscopy confirmed the formation of the magnesium oxychloride cement structure within the cell voids of both types of wood. The mineralization of the wood structure with magnesium compounds resulted in increased dimensional stability, reduced water absorption, and enhanced bulking and density of the wood. Moreover, the contact angle of water droplets on the wood’s surface decreased following impregnation with magnesium compounds, while the surface roughness of the wood increased. Mineral impregnation significantly enhances the bending strength, modulus of elasticity, impact resistance, and fire resistance of wood, regardless of heat treatment. The combined impregnation method consistently outperforms the other method.

Supercritical CO 2 offers an alternative method of removing wood moisture and reducing cellular collapse compared to traditional drying techniques. The technique has been previously demonstrated for Pinus radiata and Eucalyptus nitens dewatering and was modified in this study for New Zealand red beech ( Nothofagus fusca ) heartwood, which is notoriously difficult to dry without causing excessive distortion. The technique was also successfully extended to drying below the fibre saturation point. A specific dewatering and drying schedule was developed for N. fusca because of negligible dewatering using a schedule previously designed for wood with an open hydrofluidic network of interconnected vessels. An anatomical assessment confirmed lumen pathways were occluded with tyloses and polyphenol resins. A fluid dynamics assessment concluded that permeability measurements are recommended together with tortuosity and porosity information for improved wood species dewatering characterisation. Using the dewatering and drying schedule, collapse was successfully reduced by 92% for both normalised internal wood area and void collapse when compared to oven-dried samples. The beech specimens took 18 days to reach 17.3% moisture content (MC) but displayed some checking from early dewatering depressurisation, compared to air-dried control specimens which showed no collapse or checking but took 6 months to reach 12% MC. Supercritical CO 2 dewatering and drying could be combined with extractives separation, preservative treatment, and mechanical forming of wood in one plant to make a potentially economically viable process with improved energy, environmental and carbon footprints. A techno-economic analysis is suggested to fully compare supercritical drying of wood against conventional drying operations.

Background The identification of tropical African wood species based on microscopic imagery is a challenging problem due to the heterogeneous nature of the composition of wood combined with the vast number of candidate species. Image classification methods that rely on machine learning can facilitate this identification, provided that sufficient training material is available. Despite the fact that the three main anatomical sections contain information that is relevant for species identification, current methods only rely on transverse sections. Additionally, commonly used procedures for evaluating the performance of these methods neglect the fact that multiple images often originate from the same tree, leading to an overly optimistic estimate of the performance. Results We introduce a new image dataset containing microscopic images of the three main anatomical sections of 77 Congolese wood species. A dedicated multi-view image classification method is developed and obtains an accuracy (computed using the naive but common approach) of 95%, outperforming the single-view methods by a large margin. An in-depth analysis shows that naive accuracy estimates can lead to a dramatic over-prediction, of up to 60%, of the accuracy. Conclusions Additional images from non-transverse sections can boost the performance of machine-learning-based wood species identification methods. Additionally, care should be taken when evaluating the performance of machine-learning-based wood species identification methods to avoid an overestimation of the performance.

To accelerate development of new and improved wood adhesives for engineered wood products, the optimal adhesive penetration into wood needs to be better understood for specific products and applications. Adhesive penetration includes both flow of adhesives into wood micron-scale voids and infiltration into the polymer components of the wood cell wall layers. In this work, X-ray computed tomography (XCT) and X-ray fluorescence microscopy (XFM) were used to study adhesive flow and infiltration. Model wood–adhesive bondlines were made using loblolly pine (Pinus taeda) latewood substrates and bromine-substituted phenol formaldehyde (BrPF) resins with different weight-average molecular weights (MW). The Br substitution facilitated both qualitative and quantitative observations using XCT and XFM. The BrPF resin flow into wood was visualized using XCT volume reconstructions and quantified by calculating the weighted penetration (WP). Examination of the shape of the cured BrPF–air interface in longitudinal tracheid lumina revealed that capillary action often played a role in BrPF flow. XFM mapping revealed the pathways of BrPF infiltration into the wood cell walls, and the results were used to calculate BrPF cell wall weight percent gain (WPGCW) in individual wood cell walls. Both WP and WPGCW decreased with increasing BrPF MW. Additionally, the middle lamella had higher WPGCW than its neighboring secondary cell walls, and within a given bondline the WPGCW decreased with increasing distance of the cell from the bondline. The results provide new insights that are needed in the development of improved models to understand and predict wood–adhesive bondline performance.

Increased wood density is obtained by compressing the wood porous structure under suitable moisture and temperature conditions to improve its physical, mechanical and color properties. A recently proposed wood densification method based on partial removal of lignin and hemicellulose in hot water solution of sodium hydroxide and sodium sulphite has shown promising results on solid wood. However, its applicability and effect on thin wood veneers have not been tested yet. In this study, the timing of the method has been adapted to estimate the densification treatment intensity dependence of wood properties (wood density and modulus of elasticity) and color change of softwood (Norway spruce) and hardwood (beech) veneers. Compared to control, density and rigidity increased, with improved wood properties peaking after only 90 s of treatment intensity. Furthermore, the color became darker after treatment compared to control, with no significant color difference between treatment intensities. In conclusion, densification of veneers, according to the presented adapted method, provides a significant improvement of veneers physical and mechanical properties, and produces color changes perceptible by the human eye. Our results can be further implemented and adapted to application in industrial plants, calling for new application of densified veneers.

Manii (Maesopsis minii) is a fast-growing wood that is mainly produced for light construction and woodworking. The wood has low durability properties and requires improvements in quality. This research aims to evaluate the combination effect of boric acid, seed oil, and heating on the color of manii wood and its resistance against subterranean termites and decay fungi. The wood samples were modified by combining boric acid, neem oil, tamanu oil, and candlenut oil and heating at 70 °C and 140 °C for 4 h. The color change in the wood was evaluated using the CIELab method, while the resistance against subterranean termites (Coptotermes curvignathus) and decay fungi (Schizophyllum commune) was tested according to the SNI 7207-2014 standard. The results show that a significant color change occurred after the oil treatments. L and b values generally decreased, while the a values usually slightly increased after treatment. Boric acid significantly increased the resistance of manii wood against tested termites and fungi. The seed oils also improved wood resistance against termites, while the wood resistance against fungi significantly improved from the combination of boric acid and seed oil treatment. The lowest weight loss in termite and fungal tests occurred with the combination of boric acid and candlenut oil with heating at 140 °C.

The Moratuwa Woodworking Industry Cluster (MWIC) is a geographically concentrated cluster of over 1,600 small-to-medium scale wood-based manufacturing and retail facilities in Sri Lanka. Firms include furniture manufacturers, carpentry shops, sawmills, and integrated sawmills. The concept of industrial symbiosis explores the synergies between industrial facilities to exchange energy, water, by-products, and waste to achieve a higher efficiency in resource utilization. This research was undertaken to address the lack of quantitative information on wood residues generated within the MWIC. A survey of 180 primary and secondary wood product manufacturers was undertaken to quantify MWIC firm by-product production and consumption of wood residues to establish a baseline for possible end use and waste synergies. The total population of enterprises generating wood waste is 730; retail facilities are not included. Sawmills produce approximately 66% of the 6,490 MT of MWIC's monthly wood residue generation, with the balance produced by carpentry and integrated enterprises. Teak ( Tectona grandis ) and mahogany ( Swietenia macrophylla ) are the dominant species used in the MWIC, accounting for most of the wood waste. Three main types of wood waste were identified in the survey: sawdust (76.5%), boards with significant wane (16.5%) unusable for further products, and offcuts (6.9%). Only 55% of the wood waste generated in MWIC is currently used; the remaining 45% is taken to landfills or disposed of in other ways, such as discarded in waterways or other nonapproved locations. Improved wood waste sorting by type at the mill level and aggregated wood waste within the MWIC was determined to increase the usability of wood waste as potential inputs in other wood manufacturing sectors in the MWIC.

This study investigated whether improved downy birch could perform as well as improved silver birch, and whether there was sufficient genetic variation and control for non-destructive testing (NDT) values to include them as selection traits in breeding programs. NDT tools were applied to a 15-year-old downy birch family trial intermixed with improved silver birch. Average diameters, fissured bark height, and grain angle were higher for silver than downy birch. The genetic analysis for downy birch provided estimates of narrow-sense heritability (h2) for acoustic velocity and Pilodyn penetration depth that were above 0.3 but had low genetic variation. Grain angle had relatively high genetic variability (18%) and an h2 of 0.20. A subsample of 49 trees had 4 mm cores x-rayed for wood density estimates, and 34 stems had 12 mm cores macerated for cell measurements. t-tests revealed that average wood density and cell measurements were not significantly different between species. For silver and downy birch, fiber length and vessel length increased between inner and outer measurement positions, and fiber length was reasonably correlated with acoustic velocity. Silver birch tended to have denser and stiffer wood, while downy birch had less rough bark and straighter grain, and these results are in agreement with existing knowledge. The h2 values were similar to those observed in other birch species and indicate there is potential to breed for improved wood density and grain angle in downy birch.

Information on the weathering behaviour of Cunninghamia lanceolata (Lamb.) Hook. is needed to provide references for wood weatherproof pre-treatment and to improve wood utilization. Therefore, this study was conducted to understand the variation in the intrinsic weathering behaviour of Cunninghamia lanceolata (Chinese fir) under natural conditions. Wood samples from 15 Cunninghamia lanceolata trees aged 26–30 years old were used. The structural degradation and discoloration of wood surfaces before and after exposure were compared. The results show that the weathering behaviour of wood was weakened from heartwood to sapwood and enhanced from the bottom to the top. This study provided information for weatherability research and improved wood utilization of Cunninghamia lanceolata.

Wood is an environmentally friendly material, but some natural properties limit its wide application. To study the effect of a combination of heat treatment (HT) and wax impregnation (WI) on wood hygroscopicity, dimensional stability, and mechanical properties, samples of Pterocarpus macrocarpus Kurz wood were subjected to HT at a moderate temperature of 120 °C and a high temperature of 180 °C, for a 4 h duration. Subsequently, half of the 120 °C HT samples were treated with WI at 90 °C. The results showed that 180 °C HT and WI decreased the capacity of adsorption and liquid water uptake and swelled the wood significantly, while WI had the biggest reduction. The effect of 120 °C HT was significant only on decreasing the capacity of adsorption and the swelling of liquid water uptake. The bending strength (MOR) of wood decreased only after 180 °C HT, and 120 °C/4h HT and WI had no significant influence on MOR. The bending stiffness (MOE) increased significantly after 180 °C HT and WI, while 120 °C/4h HT had no significant influence on MOE. Therefore, the combination of moderate-temperature HT can act synergistically in the improvement of certain aspects of wood properties such as capacity of water adsorption and liquid water uptake. WI effectively improved wood hygroscopicity, dimensional stability, and mechanical properties.