Tallowwood

Scientific name

Eucalyptus microcorys. Family: Myrtaceae.

Local name

Tallowwood.

Description and natural occurrence

A moderate to large tree attaining 25 to 60 m in height and 1 to 2 m in stem diameter. The form is generally good with a straight, clear bole to two-thirds of the total height. The bark is soft, flaky, fibrous and persistent to the small branches. The brown to yellow-brownbark often has surface pores and horizontal cracks on under layers and has a characteristic spongy response to finger pressure.

Found in coastal wet sclerophyll forests from Newcastle, New South Wales to Maryborough and Fraser Island, Queensland.

Wood appearance

Colour. The heartwood ranges from pale to dark yellow brown. Sapwood is usually almost white.

Grain. Moderately coarse textured, generally with interlocked grain. Usually free from gum veins.

Wood properties

Density. 1010 kg/m3 at 12% moisture content; approximately 1.0 m3 of seasoned sawn timber per tonne.

Strength groups. S2 unseasoned; SD2 seasoned.

Stress grades. F11, F14, F17, F22 (unseasoned), F17, F22, F27, F34 (seasoned), when visually stress graded in accordance with AS 2082-1979, Visually stress-graded hardwood for structural purposes.

Joint groups. J1 unseasoned; JD1 seasoned.

Shrinkage to 12% MC. 6.1% (tangential); 3.7% (radial).

Unit shrinkage. 0.37% (tangential); 0.28% (radial). These values apply to timber reconditioned after seasoning.

Durability above-ground. Class 1 - life expectancy over 40 years.

Durability in-ground. Class 1 - life expectancy over 25 years.

Lyctine susceptibility. Untreated sapwood 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. Very hard (rated 1 on a 6 class scale) in relation to indentation. Relatively easy to work with hand tools due to its natural greasiness, and hence the descriptive name given to the timber by early settlers.

Machining. Machines and turns well.

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

Gluing. As unseasoned timber in general house framing and as seasoned dressed timber in cladding, internal and external flooring, linings and joinery. Also in fencing, landscaping and retaining walls.

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, mining timbers.

Construction. As unseasoned timber in general house framing and as dressed timber in cladding, internal and external flooring, linings and joinery. Also fencing, landscaping, and retaining walls.

Decorative. Outdoor furniture, turnery, joinery.

Others. Structural plywood, boat building (keel and framing components, planking), coach, vehicle and carriage building, agricultural machinery. Has been used for bearings, mallet heads, mauls, wheel spokes, cooling tower components, tool handles, croquet mallets.

Identification features

General characteristics

Sapwood. Pale, almost white.

Heartwood. Varies from light to dark yellow-brown.

Texture. Moderately coarse, generally with interlocked grain; greasy to touch.

Wood structure

Growth rings. Absent.

Vessels. Medium in size, solitary with some touching; a few in multiples, tending to oblique chains. Tyloses abundant. Vessel lines prominent.

Parenchyma. Visible with the aid of a lens. Abundant, paratracheal and diffuse.

Rays. Fine

Other features

Burning splinter test. Produces a charcoal tipped with grey or white ash.

Figure. Lacking, but possesses a distinctive lustre and greasy appearance.

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 16 August 2010