Woods to Know

Woods to Know: Australian Blackwood

Australian Blackwood (Acacia melanoxylon)

by Peter MacSween

Common names for trees are often misleading and Australian Blackwood is no exception. Let’s face it – the wood is not black; however, it is rich in tannins and these chemicals apparently colour the hands of woodworkers black. Nomenclature aside, the best Australian Blackwood can be a striking timber and is often used as a substitute for Hawiian Koa.
Native to Southern Australia and the island of Tasmania, Blackwood is a fast-growing, ecologically-tolerant species. It reproduces rapidly and has been planted worldwide both as an ornamental and as a timber resource in plantations. Many now consider it an invasive species as it can quickly establish dominance over local species. 


In Australia and Tasmania, it typically grows to heights of 60 - 100 feet with diameters of 2-3 feet. Outstanding individual trees will reach heights of 120 feet. The heartwood is a reddish brown to a rich golden brown. Reddish streaks and bands of dark black can add to its beautiful colouration. The sapwood is straw to pale gray in colour and is sharply demarcated from the heart. The wood dries easily if proper drying schedules are followed. Once dry, the wood is considered to be stable. 
Blackwood has a uniform, fine to medium texture. The most desirable pieces will have a distinctive fiddleback figure in addition to the interesting colours described above.  It is easy to work by machine or by hand. Figured pieces can be difficult to machine. Try skewing the wood as it is fed into the planer and adjusting cutter and feed speeds. Tooling should be sharp. 
Australian Blackwood glues and screws well. Gluing should present few problems although pieces with varying density may be prone to glue squeeze out. Clamping pressure should be carefully monitored. It takes stains very well, although the highly figured boards need little visual help. It will polish to a very high lustrous finish. 
While it is often used as an economical substitute for Koa, it lacks that species’ variations of deep gold and orange. Blackwood is a very attractive species in its own right and is used for a multitude of interior uses in its home range. It is a popular wood for furniture, cabinetry, architectural millwork and flooring. It is also used for gunstocks, decorative turnings and is a popular veneer with designers. It takes well to steam bending and is popular choice for acoustic musical instruments.

Sourcing Australian Blackwood can be a challenge. Australian timbers can be difficult to import into the country, so expect fairly high prices. Figured lumber can also be quite expensive. Reputable wood dealers are you best sources. The highest quality material still comes from Australia and Tasmania, not the other countries where it has been domesticated. Most of the Blackwood I have seen, has been imported for musical instrument use. Resourceful woodworkers may be able to incorporate this material into their projects. If you are patient and willing to source carefully, African Blackwood can be a very rewarding choice for any working project.  
Average Dried Weight40 lbs/ft³A measure of its weight at 12% moisture and an ambient temperature of 70°F.
Specific Gravity.64A measure of the ratio of its density compared to water (at 12% MC)
ShrinkageRadial: 3.9
Tangential: 7.9
Volumetric: 11.9
Radial (the amount of crosswise shrinkage);
Tangential (the amount of lengthwise shrinkage);
Volumetric (the total amount of shrinkage.)
T/R Ratio2:0A measure of the uniformity of tangential to radial shrinkage.
Janka Hardness1,160 lbfA measure of resistance to denting and abrasion.
Crushing Strength7,770 lbf/in²A measure of compression strength parallel to the grain.
Color can be highly variable, but tends to be medium golden or reddish brown, similar to Koa or Mahogany. There are usually contrasting bands of color in the growth rings, and it is not uncommon to see boards with ribbon-like streaks of color. Boards figured with wavy and/or curly grain are also not uncommon.
GrainStraight, sometimes interlocked or wavy.
TextureUniform, fine to medium.
Easily worked with both hand and machine tools, though figured wood and pieces with interlocked grain can cause tearout. Turns, glues, stains, and finishes well. Responds well to steam bending.
Veneer, furniture, cabinetry, musical instruments, gunstocks, turned objects, and other specialty wood objects.
PriceSupplies can be erratic. Check with your local dealer.
Photos and Specifications Courtesy of: The Wood Database