Red mahogany

Scientific name

Eucalyptus resinifera, E. pellita. Family: Myrtaceae

Other names

Red stringybark; red messmate (E. resinifera); red stringybark; Daintree stringybark; large-fruited red mahogany

Description

  • Medium-sized tree grows to 40–45m high and 1–1.5m stem diameter.
  • Bark is rough and persistent (doesn’t shed) up to the small branches.
  • Bark is fibrous with shallow to coarse fissures.
  • E. resinifera is greyish to reddish brown.
  • E. pellita is reddish brown to brown.

Occurrence

  • E. resinifera occurs from Jervis Bay in New South Wales to Coen in Queensland.
  • E. pellita occurs from just north of Townsville to Iron Range on Cape York Peninsula and scattered areas from Gladstone in Queensland to southern coastal New South Wales.
  • Early research trials suggest that future supplies of plantation-grown E. pellita will be available from northern Queensland on suitable soils and where the mean annual rainfall exceeds 900mm.

Appearance

Colour

  • Heartwood ranges from red to dark red.
  • Sapwood is distinctively paler.

Grain

  • Texture is, generally, medium with even grain.
  • Grain may be interlocked, producing an attractive figure (pattern).

Uses

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

Properties

  • Air dry density: 995kg/m3 at 12% moisture content; about 1.0m3 of seasoned sawn timber per tonne—density of 8.5-year-old plantation-grown timber is 70% that of mature, natural grown timber.
  • Strength groups: E. resinifera—S2 unseasoned, SD3 seasoned; E. pellita—(S2) unseasoned, (SD3) seasoned.
  • Stress grades—F11, F14, F17, F22 (unseasoned); F14, F17, F22, F27 (seasoned) when visually stress-graded according to AS 2082—2000, Timber—Hardwood—Visually stress-graded for structural purposes.
  • Joint groups: J1 unseasoned, JD1 seasoned.
  • Shrinkage to 12% MC: E. resinifera—6.3% (tangential), 3.9%(radial); 8.5-year-old plantation-grown E. pellita—5.2% (tangential), 1.9% (radial).
  • Unit shrinkage: E. resinifera—0.34% (tangential), 0.27% (radial)—values apply to timber reconditioned after seasoning; 8.5-year-old plantation-grown E. pellita— 0.28% (tangential), 0.17% (radial).
  • Durability above-ground: Class 1 (life expectancy > 40 years).
  • Durability in-ground: Class 2 (life expectancy 15–25 years).
  • Lyctine susceptibility: untreated sapwood susceptible to lyctid borer attack; timber should be sapwood-free or chemically treated before sale in Queensland.
  • Termite resistance: resistant.
  • Preservation: sapwood readily impregnates with preservative but penetration of heartwood 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; 12kN (mature native), 4.9kN (8.5-year-old plantation timber).
  • Machining: machines well.
  • 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: paler and distinct from heartwood.
  • Heartwood: generally deep red but may be lighter in younger timber.
  • Texture: uniform, coarse grain, often interlocked; an occasional tight gum vein.

Wood structure

  • Growth rings: generally absent, but some specimens may show vessels arranged in zones.
  • Vessels: medium, solitary, distributed in a diffuse pattern; obvious vessel lines on longitudinal surfaces; frequent tyloses and dark red gum deposits.
  • Parenchyma (soft tissue): amount varies, not abundant; diffuse and paratracheal.
  • Rays: fine, visible only with a lens.

Other features

  • Burning splinter test: match-size splinter burns to charcoal without 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.