Palaquium

Scientific name

Palaquium species, principally P. galactoxylum, P. hexandrum, P. ellipticum, P. obovatum, P. rostratum, P. hornei, P. amboinense. Family: Sapotaceae.

Local names

Red silkwood, bauvudi, sacau (Fiji), pencil cedar (Papua New Guinea), faibaru, maliolo (Solomon Islands), nato, red nato (Philippines), pali, njatuh, balam, punti, nantu, siki, soko, (Indonesia), kha-nunnok (Thailand).

Other species of Palaquium are sold under the standard trade names nyatoh (with other genera of the Sapotaceae family), nyatoh-batu (harder, heavier species) and red silkwood (P. galactoxylum, once harvested from Queensland forests).

Description and natural occurrence

Tall hardwoods to 30 m high and 1.0 m diameter. Some species are buttressed. Colour of the outer bark varies between species from brown, to grey to red.

The trees occur on sites as varied as coastal peat swamps to mountainous regions. Their wide distribution includes Thailand, Malaysia, Philippines, Indonesia, Papua New Guinea, Solomon Islands and Fiji.

Wood appearance

Colour. Heartwood colour varies between species, but is generally pink to red-brown. Sapwood is pink-brown and not always distinct.

Grain. Grain is straight to interlocked with a moderately fine texture.

Wood properties

Density. 540-720 kg/m3 at 12% moisture content; approximately 1.8 m3 of seasoned sawn timber per tonne.

Strength groups. S6 unseasoned; SD7 seasoned.

Stress grades. F4, F5, F7, F8 (unseasoned), F5, F7, F8, F11 (seasoned), when visually stress graded in accordance with A S2082: 2000, Timber - hardwood - visually stress-graded for structural purposes.

Joint groups. JD4 seasoned.

Shrinkage to 12% MC. 4.2% (tangential), 1.5% (radial), P. galactoxylum. 7.8% (tangential), 6.1% (radial) P. hornei. 3.9% (tangential), 1.7% (radial) P. amboinense.

Unit shrinkage. 0.29% (tangential), 0.14% (radial) P. galactoxylum. 0.36% (tangential), 0.28% (radial) P. hornei. 0.25% (tangential), 0.14% (radial) P. amboinense.

Durability above-ground. Class 4 - life expectancy less than 7 years.

Durability in-ground. Class 4 - life expectancy less than 5 years.

Lyctid susceptibility. Untreated sapwood susceptible to lyctid borer attack.

Termite resistance. Not resistant.

Preservation. Sapwood and heartwood cannot be readily impregnated with preservatives using currently available commercial processes.

Seasoning. Care required when drying palaquium to minimise distortion, collapse and checking.

Hardness. Soft (rated 5 on a 6 class scale) in relation to indentation and ease of working with hand tools.

Machining. Working properties vary with silica content. Generally palaquium is easy to work with both machine and hand tools.

Fixing. No difficulties have 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 takes a good polish after filling.

Uses

Construction. Light construction, protected framing and boards, internal covered flooring.

Decorative. Interior joinery, mouldings, lining, panelling, veneer, cabinet work.

Others. Dowels, turnery, carving, furniture carcasses, boat building. Often seen in Australia in outdoor settings and BBQ trolleys.

Identification features

General characteristics

Sapwood. Light pink-brown, only slightly differentiated from heartwood.

Heartwood. Reddish brown, pink brown, tends to fade with exposure.

Texture. Fine and even, grain straight to interlocked or wavy.

Wood structure

Vessels. Medium size, visible to the unaided eye. Some solitary, but mostly as radial multiples of two to six in chain-like formation. Tyloses present. Vessel lines conspicuous.

Parenchyma. Apotracheal as regularly spaced, fine bands.

Rays. Very fine, visible through lens only.

Other features

Burning splinter test. A match size splinter burns to an ash.

Froth test. Most species of palaquium test positive.

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 05 August 2010