Red siris

Scientific name

Paraserianthes toona. Family: Leguminosae.

Local names

Mackay cedar, acacia cedar.

Description and natural occurrence

A medium-sized tree reaching 30 m in height and 1 m in stem diameter. Stem not prominently buttressed. Bark grey or brown, scaly in parts, sometimes showing irregular depressions where the bark scales have fallen off. The bark is pink when freshly cut. Distributed mainly in North Queensland coastal rainforests between Mackay and the Endeavour River.

The availability of this timber is very limited.

Wood appearance

Colour. Dark red with some yellow streaks causing a striated pattern on the longitudinal surface. Sapwood is white in colour and up to 50 mm wide.

Grain. Coarse, large pored with pronounced vessel lines and occasional curly grain.

Wood properties

Density. 720 kg/m3 at 12% moisture content; approximately 1.4 m3 of seasoned sawn timber per tonne.

Strength group. (S5) unseasoned; (SD6) seasoned (brackets indicate provisional value).

Stress grades. F5, F7, F8, F11, (unseasoned), F7, F8, F11, F14 (seasoned), when visually stress graded in accordance with AS 2082:2000, Timber - hardwood - visually stress-graded for structural purposes.

Joint groups. JD3 seasoned.

Shrinkage to 12% MC. 4.5% (tangential); 2.0% (radial).

Unit shrinkage. Not available.

Durability above-ground. Class 3 - life expectancy 7 to 15 years.

Durability in-ground. Class 3 - life expectancy 5 to 15 years.

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

Termite resistance. Not 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. Moderately hard (rated 3 on a 6 class scale) in relation to indentation and ease of working with hand tools.

Machining. Machines and turns well to a smooth surface.

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

Construction. As sawn timber for general house framing, flooring, linings, mouldings and joinery.

Decorative. Furniture, turnery, joinery.

Identification features

General characteristics

Sapwood. Creamy yellow, distinct from heartwood.

Heartwood. Red to red brown, often with yellow or lighter coloured streaks.

Texture. Coarse texture, grain usually straight, but occasionally interlocked.

Wood structure

Growth rings. Absent.

Vessels. Medium to large in size, uniformly distributed, solitary, but also in radial chains with an infrequent cluster. Vessel lines conspicuous on longitudinal surfaces. Dark red deposits frequent in the vessels.

Parenchyma. Plentiful, aliform and confluent. The lighter coloured sheaths of soft tissue around the vessels are distinct on all surfaces.

Rays. Fine, invisible without a lens. Ripple marks occasionally present.

Other features

Burning splinter test. A match size splinter burns to a partial dark grey or black ash filament.

Figure. The parenchyma around the vessels, combined with the coloured streaks, give this timber an attractive figure.

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 06 August 2010