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Particleboards, which are widely used in various fields, are commonly coated with solid and liquid surface coating materials to achieve better physical, mechanical, and aesthetic results. This study produced low-density particleboards from waste wood bark using different adhesive mixtures and densities. These particleboards were then coated with three types of varnish: water-based (Aq), polyurethane-based (Pu), and oil/wax-based (Ow). The color, gloss, and surface roughness values of the coated boards were determined to investigate the effect of varnish type, total adhesive usage, and density on these properties. In the board groups produced with the same glue ratio and density, the roughness values obtained with Ow varnish application were mostly higher compared to Aq and Pu. In the Ow varnish type, the roughness (Rmax) decreased linearly with increasing total adhesive amount in particleboards produced at low density (320 kg/m3). The highest color change (ΔE*) values for all variations were obtained in the Ow varnish type, while the highest gloss values were achieved at 85° and in the B2 (4%-420 kg/m3) board group. It was concluded that higher density should be preferred for smoother and glossier surfaces, which are important in terms of surface properties and aesthetics. Overall, these findings highlight the preference for higher density to achieve smoother and glossier surfaces in areas where surface properties and aesthetics are significant.

Particleboards, which are widely used in various fields, are commonly coated with solid and liquid surface coating materials to achieve better physical, mechanical, and aesthetic results. This study produced lowdensity particleboards from waste wood bark using different adhesive mixtures and densities. These particleboards were then coated with three types of varnish: water-based (Aq), polyurethane-based (Pu), and oil/wax-based (Ow). The color, gloss, and surface roughness values of the coated boards were determined to investigate the effect of varnish type, total adhesive usage, and density on these properties. In the board groups produced with the same glue ratio and density, the roughness values obtained with Ow varnish application were mostly higher compared to Aq and Pu. In the Ow varnish type, the roughness (Rmax) decreased linearly with increasing total adhesive amount in particleboards produced at low density (320 kg/m³). The highest color change (ΔE*) values for all variations were obtained in the Ow varnish type, while the highest gloss values were achieved at 85° and in the B2 (4%-420 kg/m³) board group. It was concluded that higher density should be preferred for smoother and glossier surfaces, which are important in terms of surface properties and aesthetics. Overall, these findings highlight the preference for higher density to achieve smoother and glossier surfaces in areas where surface properties and aesthetics are significant. [ABSTRACT FROM AUTHOR]

Wood-derived bio-oil was used to decrease formaldehyde emissions from urea-formaldehyde (UF) resin during the process of making three-layered plywood. The obtained bio-oil urea formaldehyde (BUF) resins were characterized by their physical, chemical, and mechanical properties (e.g., viscosity, solid content, pH value, shelf life, formaldehyde emissions, and bonding strength), analyzed for their specifications, and characterized with Fourier transform infrared spectroscopy and thermogravimetric analysis. The synthesized resins were further employed to prepare the plywood with the veneers glued. The resulting BUF plywood displayed much lower formaldehyde emissions and comparable bonding strength. For the modification on formaldehyde emission of the plywood, it was concluded that the bio-oil can be used to effectively reduce formaldehyde emissions from UF wood adhesive.