Jarrah

Scientific name

Eucalyptus marginata. Family: Myrtaceae

Local name

Jarrah

Description and natural occurrence

This tree reaches a height of 30 to 40 m with a stem diameter of up to 2 m. Its bark is rough and persistent, somewhat stringy in appearance, with a fibrous texture. Jarrah is confined to the south west of Western Australia.

The timber is readily available.

Wood appearance

Colour. The heartwood is dark red. Sapwood is usually pale yellow.

Grain. Moderately coarse textured and even. Wavy, interlocking grain produces attractive fiddleback figure in some samples.

Wood properties

Density. 835 kg/m3 at 12% moisture content; approximately 1.2 m3 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 in accordance with AS2082-1979, 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 to 40 years.

Durability in-ground. Class 2 - life expectancy 15 to 25 years.

Lyctine susceptibility. Untreated sapwood is susceptible to lyctid borer attack.

Termite resistance. Resistant.

Preservation. Sapwood readily accepts preservative impregnation but penetration of heartwood is negligible using currently available commercial processes.

Seasoning. Can be satisfactorily dried using conventional air and kiln seasoning methods.

Hardness. Hard (rated 2 on a 6 class scale) in relation to indentation and ease of working with hand tools.

Machining. Machines and turns well. A planer blade angle of 15 degrees appears to give best surface quality.

Fixing. No difficulty has been experienced with the use of standard fittings and fastenings.

Gluing. Can be satisfactorily bonded using standard procedures.

Finishing Will readily accept paint, stain and polish.

Uses

Engineering. As sawn and round timber in wharf and bridge construction, railway sleepers, cross arms, poles, piles.

Construction. As 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. Has been used for bent work, butcher´s blocks, carriage and vehicle building, mauls, cooperage.

Identification features

General characteristics

Sapwood. Pale in colour, 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 in size, numerous and mainly solitary, but occasionally in oblique arrangements. Vessel lines conspicuous. Tyloses frequent. Dark red gum deposits also sometimes present.

Parenchyma. 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. A match size splinter burns to charcoal without ash.

Gum veins. Fairly common.

Further reading

Boland, DJ, Brooker, MIH, Chippendale, GM, Hall, N, Hyland, BPM, Johnston, RD, Kleinig, DA and Turner, JD 2006, 'Forest trees of Australia', 5th edn, CSIRO Publishing, Collingwood Australia.

Bootle, K 2005, 'Wood in Australia: types, properties and uses', 2nd edn, McGraw-Hill, Sydney.

Hopewell, G (ed.) 2006, 'Construction timbers in Queensland: properties and specifications for satisfactory performance of construction timbers in Queensland, Class 1 and Class 10 buildings', books 1 and 2, Department of Primary Industries and Fisheries, Brisbane.

Ilic, J 1991, 'CSIRO atlas of hardwoods', Crawford House Press, Bathurst, Australia.

Standards Australia, 2000, 'AS 2082-2000: Timber - hardwood - visually stress-graded for structural purposes', Standards Australia.

Last updated 04 August 2010