Walnut, Queensland

Queensland walnut is a large rainforest tree growing to a height of around 35 metres with a stem diameter of up to 1.8 metres. It is restricted to the coastal tablelands of North Queensland, between Innisfail and Atherton, where it is the dominant rainforest tree species.

The heartwood of the species varies in colour, but is usually greyish-brown with streaks of chocolate brown, black or pink. The sapwood, up to 100 millimetres wide, is pale yellow. Queensland walnut timber exhibits medium texture with a moderate natural lustre and shallow open pores. Grain is close and even, usually interlocked, and commonly wavy. This results in a wide variety of figure effects, especially attractive on quarter-sawn surfaces.

Uses for Queensland walnut are mainly decorative and include plywood, veneers, shop and office fixtures, turnery, and musical instruments - notably guitar backs and sides. Queensland walnut is reported to have higher than usual electrical insulation properties, and may be suitable for some types of electrical enclosure applications.

Timber produced from Queensland walnut has a life expectancy of between five and seven years (for in-ground and above ground applications, respectively). The timber is not termite-resistant, and untreated sapwood is susceptible to borer attack. Sapwood (but not heartwood) is readily impregnated with preservatives. Queensland walnut is recommended for use in continuously dry situations that are under cover, well ventilated, clear of the ground and fully protected from the weather and other dampness.

Commercial availability of Queensland walnut timber is currently very limited, due to World Heritage listing of the main sites in which it occurs.