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Forest red gum

Scientific name

Eucalyptus tereticornis, E. blakelyi ssp. blakelyi. Family: Myrtaceae

Other names

Blue gum; red gum; red iron gum

Description

  • Medium to tall forest tree.
  • Grows 20–50m high.
  • Stem diameter up to 2m.
  • Trunk is usually straight and clear for more than half its height.
  • Major limbs are more steeply inclined than in other eucalypt species.
  • Bark surface is smooth with white, grey and bluish patches from bark shedding.
  • Rough, dead bark (dark grey to black) is retained at the base of the stem.

Occurrence

  • The most extensive latitudinal distribution of the Eucalyptus genus.
  • Extends from coastal south-eastern Victoria to northwest of Laura in North Queensland.
  • Found in southern Papua New Guinea.

Appearance

Colour

  • Heartwood ranges in colour from red to dark red.
  • Sapwood is distinctly paler in colour.

Grain

  • Moderately coarse, uniform textured, usually interlocked.

Uses

  • Engineering: sawn and round timber used to construct wharves and bridges, railway sleepers, cross arms, poles, piles (including wharf piles), mining timbers.
  • Construction: sawn timber in general house framing, cladding, fascia and barge boards, internal and external flooring, linings, joinery, fencing, landscaping, retaining walls.
  • Decorative: outdoor furniture, turnery, joinery.
  • Others: structural plywood, boat building (keel and framing components, planking), coach, vehicle and carriage building.

Properties

  • Density: E. tereticornis is 1010kg/m3 and E. blakelyi ssp. blakelyi is 1055kg/m3 at 12% moisture content; about 1.0m3 of seasoned sawn timber per tonne.
  • Strength groups: E. tereticornis—S3 unseasoned, SD4 seasoned; E. blakelyi ssp. Blakelyi—(S3) unseasoned, (SD4) seasoned.
  • Stress grades: F8, F11, F14, F17 (unseasoned); F11, F14, F17, F22 (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: 8.6% (tangential), 4.8% (radial).
  • Unit shrinkage: 0.34% (tangential), 0.25% (radial)—these values apply to timber 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: E. tereticornissapwood not susceptible to lyctid borer attack; E. blakelyi ssp. blakelyi is 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: interlocked grain often makes it difficult to dress cleanly on the radial surface.
  • 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: grey or cream red, distinct from heartwood.
  • Heartwood: ranges from light to dark red.
  • Texture: uniform with interlocked grain.

Wood structure

  • Vessels: small to medium, uniformly distributed; seasonal growth zones often evident; tyloses; vessels appear pink-yellow due to associated parenchyma and deposits when viewed by lens in cross section.
  • Parenchyma (soft tissue): abundant and diffuse, containing deposits and some resin.
  • Rays: fine, visible only with a lens.

Other features

  • Burning splinter test: match-size splinter burns slowly to charcoal with no ash.

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.