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Taun

Scientific name

Pometia spp. Principally P. pinnata, P. tomentose. Family: Sapindaceae

Other names

Malugai (Philippines); kasai; sibu (Sarawak, Sabah); truong (Vietnam); aia fai; mala; ula; ako dawa (Solomon Islands); tava (Western Samoa); ahabu; matoa (Papua New Guinea); malugay; akwa

Description

  • Large hardwood with irregular bole (trunk) up to 25m.
  • Sometimes fluted with buttresses varying from shallow to high-plank type.
  • Cross-section is often elliptical with poor form, causing short log lengths.
  • Centre log diameter up to 2m.

Occurrence

  • Occurs in low-lying coastal and riverine areas from Sri Lanka through Southeast Asia, Papua New Guinea to the Solomon Islands and Samoa.

Appearance

Colour

  • Heartwood is pink-brown to red-brown, darkening with age.
  • Sapwood is pale to pink-buff and not always demarcated from heartwood.

Grain

  • Straight grained, occasionally interlocked.
  • Texture is moderately coarse.

Uses

  • Construction: sawn timber in general house framing, cladding, fascia and bargeboards, internal flooring, plywood; not suitable for external decking under Queensland conditions.
  • Decorative: lining, panelling, joinery, cabinetwork, outdoor furniture, carving, turnery, veneers; suitable for steam bending.
  • Others: boat building, handles, cooperage.

Properties

  • Density: 700kg/m3 at 12% moisture content; about 1.4m3 of seasoned sawn timber per tonne.
  • Strength groups: S4 unseasoned, SD4 seasoned.
  • Stress grades: F7, F8, F11, F14 (unseasoned); F11, F14, F17, F22 (seasoned) when visually stress-graded according to AS 2082—2000: Timber—Hardwood—Visually stress-graded for structural purposes.
  • Joint groups: S3 unseasoned, SD3 seasoned.
  • Shrinkage to 12% MC: about 5.6% (tangential), 3.4% (radial).
  • Unit shrinkage: Pometia pinnata—0.27% (tangential), 0.21% (radial)—these values apply to timber reconditioned after seasoning.
  • Durability above-ground: Class 2 (life expectancy 15–40 years).
  • Durability in-ground: Class 3 (life expectancy 5–15 years).
  • Lyctine susceptibility: untreated sapwood is susceptible to lyctid borer attack.
  • Termite resistance: not resistant.
  • Preservation: sapwood is moderately resistant to impregnating with preservative.
  • Seasoning: seasons fairly well—be careful as some collapse will occur; response to reconditioning varies.
  • Hardness: moderately hard (rated 3 on a 6-class scale) to indent and work with hand tools.
  • Machining: saws and turns easily with only moderate blunting of cutting edges.
  • Fixing: no difficulty using standard fittings and fastenings; bores readily, and holds nails and screws well.
  • Gluing: satisfactorily bonds using standard procedures.
  • Finishing: polishes to a smooth, high finish; takes paints and stains well.

Identification features

General characteristics

  • Sapwood: lighter colour but not always distinct from heartwood.
  • Heartwood: shades of red-brown, darkens with exposure.
  • Texture: medium to coarse and uniform, grain is interlocked.

Wood structure

  • Vessels: medium to large, visible without lens; solitary and radial groups generally 2–3 but occasionally 3–8; many groups consist of a large pore with a tail-like appendage of 4–8 small pores; prominent vessel lines, darker than the background surface; some tyloses.
  • Parenchyma (soft tissue): apotracheal as concentric terminal bands, and paratracheal as narrow borders to the pores.
  • Rays: fine, visible only with a lens; appear flecked with white due to the presence of crystals.

Other features

  • Burning splinter test: match-size splinter burns to an ash.
  • Frothing test: positive, with profuse and persistent lather.

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.