Purpose The surface characteristics of wood such as surface roughness, surface free energy (SFE) and wettability are important properties influencing further manufacturing processes such as gluing and coating. The purpose of this study is to determine the influence of surface roughness of ten tropical woods on their SFE, wettability and bonding quality for water-based acrylic and solvent-based alkyd varnishes. Design/methodology/approach The woods tested in this study were fast-growing teak, afrika, sungkai, mindi, merbau, durian, lamtoro, pulai, acacia and kempas. Wood surfaces were prepared in unsanded and sanded using an abrasive paper of 120 grits. SFE values were calculated based on the Rabel method. Wettability values were measured based on the contact angle between varnish liquids and wood surfaces using the sessile drop method, and the S/G model was used to evaluate the wettability of the varnishes on the woods surface. The bonding quality of the varnishes was measured using a cross-cut test based on the ASTM 3359-02 standard. Findings The results show that unsanded kempas wood had the roughest surface with a Ra value of 16.24 µm, whereas sanded lamtoro wood has the smoothest surface with a Ra value of 6.86 µm. The unsanded afrika wood had the highest SFE value of 53.61 mJ/m2, whereas sanded fast-growing teak had the lowest SFE value of 36.17 mJ/m2. Sanded merbau woods had the lowest K value of 0.022 for the water-based acrylic varnish, whereas unsanded afrika wood had the highest K value of 9.253 for the alkyd varnish. Afrika wood with the highest K values (highest wettability) for both acrylic and alkyd varnishes produced the highest bonding quality (grade 4-5). Compared to the water-based acrylic varnish, the solvent-based alkyd varnish was more wettable and generated better bonding quality. Research limitations/implications Improving the quality of fast-growing wood from plantation by painting could be considered to increase their use for higher value wood products. Practical implications Compared to water-based acrylic varnish, solvent-based alkyd varnish was more wettable and generated better bonding quality. Originality/value The originality of this research is to evaluate the values of surface free energy. SFE could be used to quantitatively determined the wettability of paints liquid in the surface of wood

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Gum benzoin (Styrax benzoin) is one of nontimber forest product classified into the resin group. The aim of the study was to determine the component from gum benzoin as an antibacterial against Staphylococcus aureus. Indonesian gum benzoin was obtained from North Sumatra and has antibacterial activity against S. aureus with the MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentrationo) values of its ethyl acetic extract of 1.00 mg/mL and 2.00 mg/mL, respectively. Thin layer chromatography (TLC) was used in purification of ethyl acetate extract of the gum benzoin. The active component was detected by TLC contact bioautography. The bands with Rf of 0.21, 0.77, and 0.87 had growth inhibition activity to the S. aureus. The active antibacterial band with Rf of 0.21 was isolated and it could be an alkaloid component.