Adhesion capability of timbers varies greatly depending on anatomical structure and origin of the species. Unlike temperate hardwood, tropical hardwood has slightly different anatomical structure due to the influence of growing season. This study evaluates the anatomical structure of three tropical hardwood species of different densities, namely, batai, sesendok and kedondong and their effects on surface roughness and wettability. Rubberwood was used as control. The fibre length, wall thickness, lumen diameter, fibre diameter, vessel diameter, density, surface roughness and wettability were determined according to the relevant standards. The study showed that the strength of the relationship varied according to species and anatomical structure. Very good correlations (r 2 > 0.8) were obtained between the anatomical characteristics and density, surface roughness and surface wettability for batai, sesendok, kedondong and rubberwood. Rubberwood behaved differently than the three species while batai and sesendok were quite similar. Density and surface roughness were highly influenced by fibre wall and cell wall thicknesses while contact angle, by fibre length, fibre diameter, fibre wall thickness and lumen diameter. Surface wettability of the wood was influenced mainly by fibre wall thickness and surface roughness.

Different loadings of nanoclay, namely 2, 4, 6, 8 and 10% were mixed into water based polyurethane by homogenisation process and were coated on rubberwood panels. Effects of the incorporation of nanoclay on the chemical, thermal properties, adhesion and mechanical properties of the wood coatings were investigated. Fourier transforms infrared analysis revealed that the polyurethane structure did not change by the addition of nanoclay. Thermogravimetric analysis showed that the coatings added with nanoclay possessed higher residual masses. Decomposition temperature of the coatings added with 2, 4 and 6% nanoclay increased, but decreased when higher loadings were used, probably attributed to the nanoclay agglomeration effect. Impact and scratch resistance of the coatings were improved by the addition of up to 6% nanoclay. On the other hand, abrasion resistance of the coatings was improved when 2% nanoclay was added but started to decrease when 4% nanoclay were used. Moreover, the addition of nanoclay slightly reduced the transparency of the water based coating. Therefore, addition of 2% nanoclay would be sufficient to obtain satisfying results as higher nanoclay content did not result in further improvement of the properties.