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Jarrah

Scientific name

Eucalyptus marginata. Family: Myrtaceae

Description

  • Grows to 30–40m.
  • Stem diameter up to 2m.
  • Bark is rough and persistent, some stringiness and fibrous.

Occurrence

  • Confined to the south west of Western Australia.
  • Timber is readily available.

Appearance

Colour

  • Heartwood is dark red.
  • Sapwood is usually pale yellow.

Grain

  • Moderately coarse texture and even.
  • Wavy, interlocking grain sometimes produces an attractive fiddleback figure (pattern).

Uses

Engineering

  • Sawn and round timber used in constructing wharves and bridges, railway sleepers, cross arms, poles, piles.

Construction

  • Sawn timber in general house framing, flooring, linings, joinery and fencing.
  • Not recommended for poles in-ground in pole-frame construction.

Decorative

  • High-quality indoor furniture, turnery, joinery, parquetry flooring, outdoor furniture.

Others

  • Used, in the past, for bent work, butcher´s blocks, carriage and vehicle building, mauls, cooperage.

Properties

  • Density: 835kg/m3 at 12% moisture content; about 1.2m3 of seasoned sawn timber per tonne.
  • Strength groups: S4 unseasoned, SD4 seasoned.
  • Stress grades: F7, F8, F11, F14 (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: J2 unseasoned, JD2 seasoned.
  • Shrinkage to 12% MC: 7.4% (tangential), 4.8% (radial).
  • Unit shrinkage: 0.30% (tangential); 0.24% (radial)—these values apply to timber reconditioned after seasoning.
  • Durability above-ground: Class 2 (life expectancy 15–40 years).
  • Durability in-ground: Class 2 (life expectancy 15–25 years.
  • Lyctine susceptibility: untreated sapwood is susceptible to lyctid borer attack.
  • Termite resistance: resistant.
  • Preservation: sapwood readily impregnates with preservative but the heartwood can’t be adequately treated using available commercial processes.
  • Seasoning: satisfactorily dries using conventional air and kiln seasoning.
  • Hardness: hard (rated 2 on a 6-class scale)  to indent and work with hand tools.
  • Machining: machines and turns well; a planer blade angle of 15° usually gives the best surface quality.
  • Fixing: no difficulty using standard fittings and fastenings.
  • Gluing: satisfactorily bonds using standard procedures.
  • Finishing: readily accepts paint, stain and polish.

Identification features

General characteristics

  • Sapwood: pale, distinct from heartwood.
  • Heartwood: dark red to pink-red, usually darkens with exposure.
  • Texture: coarse, uniform, grain usually straight, but may be interlocked.

Wood structure

  • Growth rings: mostly absent, but occasionally present as a slight zonate arrangement of thickened fibres.
  • Vessels: large to medium, numerous and mainly solitary, but occasionally in oblique arrangements; obvious vessel lines; frequent tyloses; sometimes has dark red gum deposits.
  • Parenchyma (soft tissue): paratracheal, but not readily visible to the inexperienced observer; not visible without a lens.
  • Rays: fine, numerous, not visible without a lens.

Other features

  • Burning splinter test: match-size splinter burns to charcoal without ash.
  • Gum veins: fairly common.

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.