Alstonia scholaris; Alstonia actinophylla; Wrightia laevis ssp. Millgar. Family: Apocynaceae.
Milky pine, milkwood.
|Description and natural occurrence|
A medium size to large tree attaining a height of 35 m and 1 m in stem diameter. The bark is light grey to grey, and when cut is yellowish-brown and exudes a large quantity of milky sap.
This species is widely distributed in Queensland from near Sarina to Thursday Island. It also occurs in New Guinea, South-East Asia, India and Sri Lanka.
Colour. The heartwood is white to cream with a very wide sapwood zone, which is visually indistinct from the heartwood.
Grain. Medium to coarse in texture; straight grained.
Density. A. scholaris 400 kg/m3, A. actinophylla 385 kg/m3 and W. laevis ssp. millgar 335 kg/m3 at 12% moisture content; approximately 2.5 m3 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 in accordance with AS 2082-1979, 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 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. Very susceptible to blue stain.
Hardness. Very soft (rated 6 on a 6 class scale) in relation to indentation and ease of working with hand tools.
Machining. The timber will dress and mould to a smooth finish with sharp blades and cutters.
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, but because of the coarse texture, filling may be necessary before painting or polishing.
Construction. Plywood centre veneers, mouldings, lining, treated fascia and barge boards.
Decorative. Carving, turnery.
Others. Has been used for pattern making.
Sapwood. Indistinguishable in colour from heartwood.
Heartwood. Cream to white in colour.
Texture. Medium textured, uniform.
Vessels. Medium to large in size, elliptical in shape, visible without a lens. Mostly solitary but numerous radial pairs and multiples of three or more may occur; occasionally in clusters. Vessel lines conspicuous on longitudinal surfaces.
Parenchyma. Visible as numerous fine, wavy apotracheal rows spaced about two per mm.
Rays. Fine to medium, readily visible with a lens.
Burning splinter test. A match size splinter burns to a thin partial ash.
Latex canals. May contain elongated radial pockets or latex canals as a characteristic. Note: This timber is very similar to the imported species, jelutong, from which it can be separated by the latter's more closely packed parenchyma and radial canals within the rays.
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.