Coronavirus (COVID-19) update: We are currently updating information following recent Queensland and Australian Government announcements. Find assistance and support for coronavirus affected businesses and industries.

Grey gum

Scientific name

Eucalyptus propinqua var. propinqua, E. punctata. Family: Myrtaceae

Other names

Grey iron gum (both species); small fruited grey gum E. propinqua var. propinqua

Description

  • Grows to 40m high and 1m diameter.
  • Form is generally good on better sites with a straight bole (trunk) extending for half or two-thirds the tree's height.
  • Bark decorticates (sheds) in large irregular patches exposing a cream to bright-orange surface, which weathers to grey or grey-brown.

Occurrence

  • Varieties of grey gum occur along the east coast of Australia from Wyong, New South Wales, to Maryborough and inland to the Carnarvon Ranges and Blackdown Tablelands in Queensland.

Appearance

Colour

  • Heartwood is red to red-brown.
  • Sapwood is distinctly paler.

Grain

  • Grain usually interlocked, with coarse but even texture.
  • Occasionally marked by grub holes.

Uses

  • Engineering: railway sleepers, landscaping sleepers, cross-arms, poles, piles, mining timbers.
  • Construction: framing, flooring, retaining walls.
  • Others: boat building, butcher's blocks.

Properties

  • Density: 1055kg/m3 at 12% moisture content; about 1.0m3 of seasoned sawn timber per tonne.
  • Strength groups: S1 unseasoned, (SD2) seasoned.
  • Stress grades: F14, F17, F22, F27 (unseasoned); F17, F22, F27, 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: 7.0% (tangential), 4.5% (radial).
  • 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: sapwood not susceptible to lyctid borer attack.
  • Termite resistance: resistant.
  • Preservation: sapwood readily accepts preservative.
  • Seasoning: slow to dry, but little degrade occurs.
  • Hardness: very hard (rated 1 on a 6-class scale) to indent and work with hand tools.
  • Machining: machines well, however, be careful with interlocked grain.
  • Fixing: no difficulties with 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: pale, reddish brown distinguishable from heartwood.
  • Heartwood: reddish brown to red.
  • Texture: medium to coarse, interlocked grain.

Wood structure

  • Vessels: small, solitary, uniform distribution; vessel lines prominent in some specimens of darker colour; abundant tyloses.
  • Parenchyma (soft tissue): not visible with lens.
  • Rays: fine.

Other features

  • Burning splinter test: match-size splinter burns to charcoal leaving 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.