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Palaquium

Scientific name

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

Other 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

  • Tall hardwood to 30m high and 1m diameter.
  • Some species are buttressed.
  • Outer bark is brown, grey or red depending on species.

Occurrence

  • Occurs on varied sites from coastal peat swamps to mountainous regions.
  • Widely distributed including:
    • Thailand
    • Malaysia
    • Philippines
    • Indonesia
    • Papua New Guinea
    • Solomon Islands
    • Fiji.

Appearance

Colour

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

Grain

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

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.

Properties

  • Density: 540–720 kg/m3 at 12% moisture content; about 1.8m3 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 according to AS 2082—2000: Timber—Hardwood—Visually stress-graded for structural purposes.
  • Joint groups: JD4 seasoned.
  • Shrinkage to 12% MC: P. galactoxylum—4.2% (tangential), 1.5% (radial); P. hornei—7.8% (tangential), 6.1% (radial); P. amboinense—3.9% (tangential), 1.7% (radial).
  • Unit shrinkage: P. galactoxylum—0.29% (tangential), 0.14% (radial); P. hornei—0.36% (tangential), 0.28% (radial); P. amboinense—0.25% (tangential), 0.14% (radial).
  • 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: be careful when drying to minimise distortion, collapse and checking.
  • Hardness: soft (rated 5 on a 6-class scale) to indent and work with hand tools.
  • Machining: working properties vary with silica content; generally, easy to work with both machine and hand tools.
  • Fixing: no difficulties using standard fittings and fastenings.
  • Gluing: satisfactorily bonds using standard procedures.
  • Finishing: readily accepts paint, stain, and takes a good polish after filling.

Identification features

General characteristics

  • Sapwood: light pink-brown, only slightly distinct from heartwood.
  • Heartwood: reddish brown, pink brown, tends to fade with exposure.
  • Texture: fine and even, grain is straight to interlocked or wavy.

Wood structure

  • Vessels: medium size, visible to the unaided eye; some solitary, but mostly as radial multiples of 2–6 in chain-like form; tyloses ; obvious vessel lines.
  • Parenchyma (soft tissue): apotracheal as regularly spaced, fine bands.
  • Rays: very fine, visible through lens only.

Other features

  • Burning splinter test: match-size splinter burns to an ash.
  • Froth test: most species of palaquium test positive.

Research and resources

  • Boland, DJ, Brooker, MIH, Chippendale, GM, Hall, N, Hyland, BPM, Johnston, RD, Kleinig, DA and Turner, JD 2006, Forest trees of Australia, 5th ed., CSIRO Publishing, Collingwood Australia.
  • Bootle, K 2005, Wood in Australia: Types, properties and uses, 2nd ed., McGraw-Hill, Sydney.
  • Ilic, J 1991, CSIRO atlas of hardwoods, Crawford House Press, Bathurst, Australia.
  • Queensland Government, DAF 2018, Construction timbers in Queensland: Properties and specifications for satisfactory performance of construction timbers in Queensland. Class 1 and Class 10 buildings, Books 1 & 2, Department of Agriculture and Fisheries, Brisbane.
  • Standards Australia, 2000, AS 2082—2000: Timber—Hardwood—Visually stress-graded for structural purposes, Standards Australia International, Strathfield, NSW.