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Grey ironbark

Scientific name

Eucalyptus drepanophylla, E. paniculata. Family: Myrtaceae

Other names

White ironbark; narrow-leaved ironbark

Description

  • Medium-sized tree growing 30–50m.
  • Stem grows to 1.5m diameter.
  • Stem is usually straight and free of branches for a considerable length.
  • Bark is hard, coarse, deeply furrowed and ridged.
  • Bark ranges from dark brown to black and is persistent (doesn’t shed) to the small branches.

Occurrence

E. drepanophylla:

  • Northern New South Wales to Bundaberg, Queensland
  • Scattered patches as far north as the Atherton Tableland.

E. paniculata:

  • New South Wales only from Bega to Coffs Harbour.

Appearance

Colour

  • Heartwood ranges from reddish brown to dark brown.
  • Sapwood is lighter in colour and averages about a 20mm wide band.

Grain

  • Tight and usually straight grained.

Uses

Engineering

  • Sawn and round timber used to construct wharf and bridges, railway sleepers, cross arms, poles, piles, mining timbers.

Construction

  • Unseasoned timber in general house framing.
  • Seasoned dressed timber in cladding, internal and external flooring, linings and joinery.
  • Fencing, landscaping and retaining walls.

Decorative

  • Outdoor furniture, turnery, joinery.

Others

  • Boat building (keel and framing components, planking), coach, vehicle and carriage building, agricultural machinery, mallet heads, mauls, bearings, sporting goods (croquet mallets, parallel bars).
  • Past use for wheel spokes and bowling ninepins.
  • Reputedly, the timber of choice for wooden-hulled vessels used in Antarctic exploration due to the timber’s high strength and toughness providing high resistance to pack ice damage and crushing.

Properties

  • Density: 1105 kg/m3 at 12% moisture content; about 0.9m3 of seasoned sawn timber per tonne.
  • Strength groups: S1 unseasoned, SD1 seasoned.
  • Stress grades: F14, F17, F22, F27 (unseasoned), F22, F27, F34, F34 (seasoned), when visually stress-graded according to AS 2082—2000: Timber—Hardwood—Visually stress-graded hardwood for structural purposes.
  • Joint groups: J1 unseasoned, JD1 seasoned.
  • Shrinkage to 12% MC: 7.5% (tangential), 4.7% (radial).
  • Unit shrinkage: 0.39% (tangential), 0.31% (radial)—these values apply to timber of E. paniculata reconditioned after seasoning.
  • Durability above-ground: Class 1 (life expectancy more than 40 years).
  • Durability in-ground: Class 1 (life expectancy more than 25 years).
  • Lyctine susceptibility: sapwood is not susceptible to lyctid borer attack.
  • Termite resistance: resistant.
  • Preservation: sapwood readily impregnates with preservative, unlike the  heartwood, where penetration is negligible using available commercial processes.
  • Seasoning: satisfactorily dries using conventional air and kiln seasoning.
  • Hardness: very hard (rated 1 on a 6-class scale) to indent and work with hand tools.
  • Machining: not easily worked because of its high density; dressed surfaces have a steely sheen.
  • Fixing: no difficulty 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: almost white, distinct from heartwood.
  • Heartwood: varies from reddish brown to dark brown.
  • Texture: uniform, grain usually straight, sometimes interlocked.

Wood structure

  • Growth rings: absent.
  • Vessels: small to medium, solitary and diffuse, often containing tyloses.
  • Parenchyma (soft tissue): sparse, not visible with a lens.
  • Rays: fine, visible with a lens.

Other features

  • Burning splinter test: produces a complete ash, grey to buff.
  • Splinter shape: fine needle-like splinters are produced when cutting across the grain—characteristic of this species and can be used to separate them from similar species.

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.