White mahogany

Scientific name

Eucalyptus acmenoides, E. umbra ssp. umbra, E. carnea, E. tenuipes. Family: Myrtaceae.

Local names

Yellow stringybark, white stringybark.

Description and natural occurrence

E. acmenoides is a tall tree attaining a height of 60 m and a stem diameter over 1 m. E. umbra ssp. umbra and carnea are small to medium sized trees of 8 to 25 m in height and up to 1 m stem diameter. The greyish-brown bark of these species is rough, fibrous and persistent over the whole trunk and branches and tends to be stringy.

E. acmenoides is common in coastal areas from Sydney, New South Wales, to Rockhampton, Queensland, and isolated areas north to the Atherton Tableland.

E. umbra ssp. umbra occurs from Sydney, New South Wales, to Cooktown in Queensland, though absent between Rockhampton and Townsville. E. umbra ssp. carnea occurs from Wyong, New South Wales to Bundaberg in Queensland.

Sawn timber of white mahogany is readily available.

Wood appearance

Colour. Heartwood yellow brown, having a close resemblance to tallowwood. Sapwood is usually paler in colour and less than 20 mm wide.

Grain. Generally medium textured and uniform; however, at times it can be interlocked. Greasy to feel, but not as pronounced as in tallowwood and spotted gum.

Wood properties

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

Strength groups. Eucalyptus acmenoides S2 unseasoned; SD3 seasoned. E. umbra ssp. umbra, E. carnea, E. tenuipes (S2) unseasoned; (SD3) seasoned
(brackets indicate provisional value).

Stress grades. F11, F14, F17, F22, (unseasoned), F14, F17, F22, F27(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. E. acmenoides 6.0% (tangential); 3.5% (radial). E. umbra ssp. carnea 5.4% (tangential); 2.8% (radial).

Unit shrinkage. Not available.

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

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

Lyctine susceptibility. Eucalyptus acmenoides, E. umbra ssp. umbra, E. carnea sapwood not susceptible to lyctid borer attack; E. tenuipes susceptible.

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 and ease of working with hand tools.

Machining. Machines and turns well due to its greasy nature.

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

Gluing. As with most high-density species, machining and surface preparation should be done immediately before gluing.

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 sawn timber in general house framing, cladding, internal and external flooring, linings, joinery, fencing, landscaping, retaining walls.

Decorative. Outdoor furniture, turnery, joinery.

Others. Structural plywood, boat building (keel and framing components, planking), coach, vehicle and carriage building, agricultural machinery.

Identification features

General characteristics

Sapwood. Creamy-brown and distinctly lighter than heartwood.

Heartwood. Light brown to yellow-brown.

Texture. Medium textured and uniform; grain interlocked; greasy to feel, but not as pronounced as in tallowwood and spotted gum.

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 17 August 2010