Brown salwood

Scientific name

Acacia aulacocarpa, A. mangium, A. crassicarpa. Family: Leguminosae

Local names

Black wattle, hickory wattle (both species), sally wattle (A. mangium only). A lesser species, A. crassicarpa, is also known as brown salwood.

Description and natural occurrence

Medium sized hardwoods with flanged buttresses at the base, attaining 30 m in height and 1 m diameter on favourable sites. Bark is thin, brown, hard and fissured.

Occurs from northern New South Wales along the eastern coast of Queensland to Cape York, and also in the coastal areas of the Northern Territory.

Wood appearance

Colour. Heartwood varies from light brown to brown, often streaked with darker markings. Sapwood creamy-white to pale brown.

Grain. Grain variable, texture coarse but rather even.

Wood properties

A. aulacocarpa, A. mangium, A. crassicarpa

Density. A. aulacocarpa 800 kg/m3, A. mangium 690 kg/m3 and A. crassicarpa 675 kg/m3 at 12% moisture content; approximately 1.3 m3 of seasoned sawn timber per tonne.

Strength groups. A. aulacocarpa (S4) unseasoned; (SD4) seasoned; A. mangium (S5) unseasoned; (SD5) seasoned; A. crassicarpa (S5) unseasoned; (SD5) seasoned.

Stress grades. A. aulacocarpa F7, F8, F11, F14 (unseasoned), F11, F14, F17, F22 (seasoned); A. mangium F5, F7, F8, F11 (unseasoned), F8, F11, F14, F17 (seasoned); A. crassicarpa F5, F7, F8, F11 (unseasoned), F8, F11, F14, F17 (seasoned) when visually stress graded in accordance with AS 2082-1979, Visually stress-graded hardwood for structural purposes.

Joint groups. A. aulacocarpa JD2 seasoned. A. mangium JD3 seasoned. A. crassicarpa J2 unseasoned; JD3 seasoned.

Shrinkage to 12% MC. 4.2% (tangential); 1.4% (radial). These values apply to A. aulacocarpa.

Unit shrinkage. 0.36% (tangential); 0.14% (radial). These figures apply to timber of A. aulacocarpa reconditioned after seasoning.

Durability above-ground. A. aulacocarpa Class (2) - life expectancy 15 to 40 years. A. mangium Class (3) - life expectancy 7 to 15 years. A. crassicarpa Class (3) - life expectancy 7 to 15 years.

Durability in-ground. A. aulacocarpa Class 2 - life expectancy 15 to 25 years. A. mangium Class 3 - life expectancy 5 to 15 years. A. crassicarpa Class 3 - life expectancy 5 to 15 years.

Lyctine susceptibility. Untreated sapwood susceptible to lyctine borer attack.

Termite resistance. Not resistant.

Preservation. Sapwood accepts preservative impregnation.

Seasoning. Can be satisfactorily dried using conventional air and kiln seasoning methods.

Hardness. Moderately hard (rated 3 on a 6 class scale) in relation to indentation and ease of working with hand tools.

Machining. Relatively easy to work and machine. Turns well to a smooth finish.

Fixing. No difficulties have been experienced with the use of standard fittings and fastenings.

Gluing. Can be satisfactorily bonded using standard procedures.

Finishing. Staining is normally not necessary. It polishes and paints well.

Uses

Construction. Once had limited use in general house framing, flooring, linings and mouldings, but is rarely used for these applications now.

Decorative. Plywood, furniture, shop and office fixtures, joinery, turning, walking sticks.

Others. Fishing rods, archery bows, tool handles (axes and hammers), boat building (light).

Identification features

General characteristics

Sapwood. Creamy-white, distinct from heartwood.

Heartwood. Light-brown through to chestnut, occasionally with darker streaks.

Texture. Medium to coarse. Straight grain. Lustrous.

Wood structure

Vessels. Medium to large, visible without lens, solitary and radial chains of up to three, uniform distribution. A tendency for vessel size to decrease with the zone of latewood. Vessel lines visible.

Parenchyma. Indistinct.

Rays. Very fine, barely visible with lens.

Other features

Burning splinter test. A match size splinter burns to charcoal.

Further reading Boland, DJ, Brooker, MIH, Chippendale, GM, Hall, N, Hyland, BPM, Johnston, RD, Kleinig, DA and Turner, JD 2006, 'Forest trees of Australia', 5th edn, CSIRO Publishing, Collingwood Australia.

Bootle, K 2005, 'Wood in Australia: types, properties and uses', 2nd edn, McGraw-Hill, Sydney.

Hopewell, G (ed.) 2006, 'Construction timbers in Queensland: properties and specifications for satisfactory performance of construction timbers in Queensland, Class 1 and Class 10 buildings', books 1 and 2, Department of Primary Industries and Fisheries, Brisbane.

Ilic, J 1991, 'CSIRO atlas of hardwoods', Crawford House Press, Bathurst, Australia.

Standards Australia, 2000, 'AS 2082-2000: Timber - hardwood - visually stress-graded for structural purposes', Standards Australia.

Last updated 04 August 2010