Drilling resistance method to evaluate density and hardness properties of resinous wood of agarwood (Aquilaria malaccensis)
Gaharu or agarwood is produced by certain trees in response to fungal infections and wounds. The response is a pathological process that alters the physiological and chemical compounds produced in tree wood, yielding a fragrant resinous material. We investigated the density and hardness properties of agarwood using the drilling resistance method in 25 disks of Aquilaria malaccensis that had previously been inoculated with Fusarium solani. A micro drilling technique was applied in two directions across the diameter of the disks to measure resistance, starting in the part containing agarwood. In addition, hardness properties were determined based on the Janka test and density was measured based on the gravimetric method. We found that hardness properties varied greatly in disks containing agarwood. A low correlation was found between the amplitude of resistance and hardness and density, indicating that other variables beyond density are also involved in the changes of wood properties in agarwood. A strong correlation was observed between hardness and wood density.