White cheesewood

Scientific name

Alstonia scholaris; A. actinophylla; Wrightia laevis ssp. Millgar. Family: Apocynaceae

Other names

Milky pine; milkwood

Description

  • Medium to large tree, grows to 35m high.
  • Stem grows to 1m diameter.
  • Bark is light grey to grey, and when cut is yellowish brown and exudes a large quantity of milky sap.

Occurrence

  • Widely distributed in Queensland from near Sarina to Thursday Island.
  • Occurs in:
    • New Guinea
    • Southeast Asia
    • India
    • Sri Lanka.

Appearance

Colour

  • Heartwood is white to cream.
  • Very wide sapwood zone, which is visually indistinct from the heartwood.

Grain

  • Medium to coarse texture.
  • Straight grain.

Uses

  • Construction: plywood centre veneers, mouldings, lining, treated fascia and barge boards.
  • Decorative: carving, turnery.
  • Others: previously used for pattern-making.

Properties

  • Density: A. scholaris—400 kg/m3, A. actinophylla—385 kg/m3 and W. laevis ssp. millgar—335 kg/m3 at 12% moisture content; about 2.5m3 of seasoned sawn timber per tonne.
  • Strength groups: A. scholaris—S7 unseasoned, SD8 seasoned; A. actinophylla—(S7) unseasoned, (SD8) seasoned; W. laevis ssp. Millgar—(S<7) unseasoned, (SD<8) seasoned (brackets indicate provisional value).
  • Stress grades: F4, F5, F7, (unseasoned); F4, F5, F7, F8 (seasoned) when visually stress-graded according to AS 2082—2000: Timber—Hardwood—Visually stress-graded hardwood for structural purposes.
  • Joint groups: A. scholaris and A. actinophylla—J5 unseasoned, JD5 seasoned; W. laevis ssp. Millgar—JD6 seasoned.
  • Shrinkage to 12% MC: 4.0% (tangential), 2.5% (radial).
  • Unit shrinkage: not available.
  • Durability above-ground: Class 4 (life expectancy less than 7 years).
  • Durability in-ground: Class 4 (life expectancy less than 5 years).
  • Lyctine susceptibility: susceptible.
  • Termite resistance: not resistant.
  • Preservation: sapwood readily impregnates with preservative, impregnation but penetration of heartwood is negligible using available commercial processes.
  • Seasoning: can be satisfactorily dried using conventional air and kiln seasoning; very susceptible to blue stain.
  • Hardness: very soft (rated 6 on a 6-class scale) to indent and work with hand tools.
  • Machining: will dress and mould to a smooth finish with sharp blades and cutters.
  • Fixing: no difficulty using standard fittings and fastenings.
  • Gluing: satisfactorily bonds using standard procedures.
  • Finishing: readily accepts paint, stain and polish, but you may need to fill the coarse texture before painting or polishing.

Identification features

General characteristics

  • Sapwood: indistinguishable in colour from heartwood.
  • Heartwood: cream to white.
  • Texture: medium texture, uniform.

Wood structure

  • Vessels: medium to large, elliptical, visible without a lens; mostly solitary but numerous radial pairs, may occur in multiples of 3 or more, or occasionally in clusters; obvious vessel lines on longitudinal surfaces.
  • Parenchyma (soft tissue): visible as numerous fine, wavy apotracheal rows spaced about 2 per mm.
  • Rays: fine to medium, readily visible with a lens.

Other features

  • Burning splinter test: match-size splinter burns to a thin partial ash.
  • Latex canals: may contain elongated radial pockets or latex canals as a feature; jelutong, a very similar imported species, can be distinguished by more closely packed parenchyma and radial canals within the rays.

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.