Short rotation teak (SRT) has a diameter of around 30 cm at the age of 15 years; however, the wood still has low quality, especially in dimensional stability and biological durability. The objective of this study was to improve dimensional stability and biological durability of SRT through modification treatment using non-biocide chemicals, citric acid (CA) and benzophenone tetracarboxylic acid (BPTCA). SRT sapwood was impregnated by 20% and 40% of CA or BPTCA followed by heating in the oven at 150 °C for 2 h. Dimensional stability, strength, surface characteristics and durability against termite attacks of the modified woods were evaluated. Results show that dimensional stability as anti-swelling efficiency (ASE) increased by an average of 46% (CA) and 50% (BPTCA) after treatments. Durability against termites showed that the modified woods were categorized to be class 1 (very durable). Fourier Transform Infrared (FTIR) and X-ray Diffraction observations indicated a possible chemical reaction between the wood components with CA and BPTCA. The water-based acrylic and oil-based alkyd contact angle values of the modified woods were lower than 90°, indicating their high wetting ability against the varnish liquids. The treatment can be applied to improve the quality of SRT for high-quality wood product utilization.

Chemical and thermal modification can change the hydrophilic properties of wood, and thus affect their coating performance. This study determined the surface characteristics of chemically and thermally modified short rotation teak wood. The characteristics studied were surface roughness, surface free energy (SFE), contact angle, wettability, and coating bonding quality. Results show that the surface of short rotation teak became smoother after chemical and thermal modifications; however, surface roughness increased after furfurylation. The total SFE of chemically and thermally modified teak wood decreased after treatment. The decrease in the total SFE caused the decrease in the constant contact angle change rate (K-value). The K-values for water-dispersed polyurethane and acrylic paints were nearly 0, which indicated their lower wettability. The paint bonding quality decreased after accelerated weathering. Short rotation teak with Glycerol-Maleic Anhydride (GMA)-thermal treatment can be considered for exterior applications with a proper selection of paint.