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The Blackwood Tree (Acacia melanoxylon)
The Australian Blackwood tree is usually found as an understory
tree in large eucalypt forests where rainfall is 750 - 1800
mm annually.
It can be a fine, erect tree 25-30 m high but is more often
16m or less with a trunk 30-100 cm in diameter. The branches
begin well down the trunk, are horizontal or slightly pendulous,
and culminate in a dense rounded crown, the overall effect
being very handsome (*1).
The picture on the right shows me and a
young Blackwood on my golf course. Blackwood is almost a
twin with Hawian Koa and is rapidly gaining recognition
as one of the great guitar woods of the world.
Click on the photo for a full-size view -->
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The Wood:
Blackwood (Acacia melanoxylon)
Size:
A medium sized hardwood of occasional occurrence in table-land
areas in South Australia and all the eastern States, but
the only areas of considerable commercial yield are the
wetter districts of Tasmania.
Description:
The heartwood is golden brown, often with narrow bands of
darker colour indicating growth rings. Sometimes reddish
streaks are also present. The sapwood is distinctly paler
and up to 50mm wide. Texture is medium and even. The grain
is usually straight but sometimes wavy, producing a fiddleback
figure.
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Green density and air dry density (at 12%):
GD about 870 kg/m3, ADD about 640 kg/m3 (40 Lb/Cub. Ft.)
Drying and shrinkage characteristics: Easy to dry with little
checking and negligible collapse. Shrinkage about 1.5% radial,
4% tangential.
Workability:
Easy to work but planer angle may need reducing for figured material.
Good for steam bending. Glues and nails well. It can be bleached
white with ammonia and hydrogen peroxide. The sanding dust is
irritant to the skin and bronchial tubes of some people. Spots
of a dark exudate may appear sometimes but readily sand off and
do not appear to affect finishes.
Use:
Used in furniture, decorative veneer, panelling, carving, turnery,
flooring, boatbuilding, gunstocks.
Availability:
Confined to relatively small sizes. It is a species whose wider
cultivation should be encouraged (*2).
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Blackwood for Guitar making.
Blackwood has similar density and modulus of elasticity
to Maple but is open grained with good light reflection
from medullary rays (like Mahogany) and in figured pieces
displays excellent colour and figure variations.
These properties make Blackwood an excellent guitar wood,
combining the characteristics of the three traditional acoustic
guitar woods (Mahogany, Maple and Rosewood) both in appearance
and acoustic properties.
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In recent years I have "evolved" into using Blackwood
in solid body electrics (bolt-on and plank necks), basses, semi-acoustics
and acoustics. This has involved some minor design changes in
some models and has met with excellent acceptance in the Australian
market, renown for its' conservatism and preference for American
guitars and woods. Although extremely difficult to acquire select
timber, which essentially must be sourced as it is felled and
broken down and seasoned in house, the results have been well
worthwhile (*3).
3 May 1996
References
*1 Holliday, I. (1989). A field guide
to Australian Trees - Hamlyn
*2 Bootle, K. R. (1991). Wood in
Australia - McGraw Hill
*3 Ian Noyce, Noyce Guitars, Ballarat,
Australia.
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