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Spear wattle

Scientific name

Acacia rhodoxylon. Family: Leguminosae

Other names

Brown spearwood; rosewood

Description

  • Small tree, grows to 10–15m high.
  • Stem is 15–25cm diameter.
  • Stem and branches are often fluted.
  • Bark is dark and sheds in curly flakes.

Occurrence

  • Found in coastal and subcoastal parts of Central Queensland from near Eidsvold, north to southeast of Mt Garnet.

Appearance

Colour

  • Heartwood is deep red-brown to dark brown.
  • Sapwood is cream to white.

Grain

  • Grain is straight.
  • If present, interlocked or wavy grain gives a 'ring' feature to polished surfaces.
  • Texture is very fine and even.

Uses

Engineering and construction

  • Used extensively, in the past, for fence posts.
  • Not generally available in sizes suitable for engineered uses, even though strong enough—more suited to uses listed below.

Decorative

  • Fancy turnery, walking sticks, 'ringed' timber especially prized.

Others

  • Resonating parts of xylophones.
  • Fingerboards and chin rests for violins (a substitute for ebony).
  • Straight-grained timber may be used for sporting goods.
  • Future potential for use in 'small-volume, high-value' niche markets.

Properties

  • Density: 1280kg/m3 at 12% moisture content; about 0.75m3 of seasoned sawn timber per tonne.
  • Strength groups: (S1) unseasoned, (SD1) seasoned (brackets indicate provisional value).
  • Stress grades: F14, F17, F22, F27 (unseasoned); F22, F27, F34 (seasoned) when visually stress-graded according to AS 2082—2000: Timber—Hardwood—Visually stress-graded hardwood for structural purposes.
  • Joint groups: JD1 seasoned.
  • Shrinkage to 12% moisture content: not available.
  • Unit shrinkage: not available.
  • Durability above-ground: Class 1 (life expectancy more than 40 years).
  • Durability in-ground: Class 1 (life expectancy more than 25 years).
  • Lyctine susceptibility: untreated sapwood susceptible to lyctid borer attack.
  • Termite resistance: not resistant.
  • Preservation: sapwood readily impregnates with preservative but penetration of heartwood is negligible using available commercial processes.
  • Seasoning: dries slowly with little degrade.
  • Hardness: very hard (rated 1 on a 6-class scale) to indent and work with hand tools.
  • Machining: using appropriate tooling and feed speeds, spear wattle dresses and machines well, resulting in a fine polish.
  • Fixing: moderately fissile, be careful using standard fittings and fastenings.
  • Gluing: as with most high-density species, machine and prepare surface immediately before gluing.
  • Finishing: readily accepts paint, stain and polish.

Identification features

General characteristics

  • Sapwood: cream, distinct from heartwood.
  • Heartwood: deep red-brown to dark brown.

Wood structure

  • Vessels: solitary; small, indistinct to the naked eye; moderately numerous (4–12 per mm2).
  • Vessel lines: fine, indistinct.
  • Parenchyma (soft tissue):indistinct under a lens.
  • Rays: fine, barely visible with a lens.

Other features

  • Burning splinter test: match-size splinter burns slowly with a small, steady flame; embers glow for a long time, leaving a charcoal tip.

Research and resources

  • Boland, DJ, Brooker, MIH, Chippendale, GM, Hall, N, Hyland, BPM, Johnston, RD, Kleinig, DA and Turner, JD 2006, Forest trees of Australia, 5th ed., CSIRO Publishing, Collingwood, Australia.
  • Bootle, K 2005, Wood in Australia: Types, properties and uses, 2nd ed., McGraw-Hill, Sydney.
  • Ilic, J 1991, CSIRO atlas of hardwoods, Crawford House Press, Bathurst, Australia.
  • Queensland Government, DAF 2018, Construction timbers in Queensland: Properties and specifications for satisfactory performance of construction timbers in Queensland. Class 1 and Class 10 buildings, Books 1 & 2, Department of Agriculture and Fisheries, Brisbane.
  • Standards Australia, 2000, AS 2082—2000: Timber—Hardwood—Visually stress-graded for structural purposes, Standards Australia International, Strathfield, NSW.