This study aimed to evaluate the effect of oil-heat treatment on the anatomical, physical, and chemical properties of the tropical fast-growing wood species as gmelina (Gmelinaarborea) and mindi (Melia azedarach) wood. Vessel lumen area and diameter in radial and tangential direction of both species increased with increasing temperature. The fiber lumen areas in both woods were remarkably decreased by oil-heat treatment, and the fiber wall area increased considerably with increasing temperature. Both woods tended to gain weight after heat treatment at 180°C and 200°C, and then lose weight after heat treatment at 220°C. The density of mindi increased greatly at 180°C and 200°C and slightly decreased at 220°C. The dimension of the specimens in tangential direction increased with heat treatment, but the rate decreased with increasing temperature. The relative crystallinity and crystallite width of the heat-treated woods were greater than those of the untreated wood. In the Fourier transform infrared analyses, the peaks from the carbohydrates were changed after oil-heat treatment, mainly due to the degradation of hemicellulose. Consequently, it was revealed that the heat treatment affected various properties of gmelina and mindi woods. Differing characteristics between the species were also noted.

Most of wood in Indonesia is dominated by fast-growing wood such as gmelina (Gmelina arborea) and materials such as coconut (Cocos nucifera). Using fast-growing woood natural forests, increase economic growth, and is more environment friendly. The objective of this study was to improve the wood properties of G. arborea and C. nucifera via hot oil treatment. The experiment was conducted in a lab-scale furnace using a commercial grade palm oil at 180ºC, 200ºC, 220ºC, and 240ºC for 3 h. The effect of hot oil treatment on color change, physical, and mechanical properties was evaluated. The results showed that increasing treatment temperature increase of the overall color change (ΔE*) in both G. arborea and C. nucifera. The density of G. arborea and C. nucifera decreased with increased temperature. The results also showed that increase in temperature reduced the moisture content, density and water absorption in both woods. The compressive strength of G. arborea and C. nucifera decreased with the increase in treatment temperature.

Fast growing wood has high potential in increasing numbers but has a low quality so that it requires modification to improve wood quality. Oil heat treatment (OHT) is one of a wood modification method using vegetable oil as a heat conducting medim. The objective of this study was to analyze the effect of temperature OHT on color change (ΔL*, Δa*, Δb*, and ΔE), physical properties (density, moisture content, water absorption, and weight changes), and the compressive strength of mindi (Melia adezarach) and sengon (Paraserianthes falcataria). OHT was conducted using 2 hours duration on temperature 180C, 200C, 220C, and 240C. The results showed that the effect of temperature on wood color inflicted an increase in the values of ΔL*, Δa*,Δb*, and ΔE on higher temperature of OHT. The effect of temperature on the physical properties of wood results in an increase on density at certain temperature and wood species as well as decreasing moisture content, water absorption, and weight changes of wood on higher temperature of OHT. The effect of temperature on mechanical properties of wood results in increasing compressive strength at certain temperatures and types of wood, but there is decrease compressive strength in the higher temperature of OHT.Keywords:   Color change, oil hot treatment, mechanical properties, physical properties