Red balau

Scientific name

Shorea principally S. kunstleri, S. guiso, S. collina, S. ochrophloia. Family: Dipterocarpaceae.

Local names

Red selangan, urat mata, seangan merah (Sabah, Sarawak), bangkiri (Borneo), chan (Thailand), guijo (Phillipines), giso, membatu (Indonesia).

Note: The name balau is also used for some species of Hopea.

Description and natural occurrence

Medium to large hardwoods, often buttressed, with a straight cylindrical bole between 30 and 50 m long. Shorea spp. grow across a variety of areas in Indonesia, Malaysia, Thailand and the Philippines.

Wood appearance

Colour. Heartwood red-brown to purple-brown, sapwood distinctly paler.

Grain. Grain varies from straight to interlocked. Interlocking grain produces striped figure on quarter-sawn material. Texture moderately coarse but even.

Wood properties

Density. 840 kg/m3 at 12% moisture content; approximately 1.2 m3 of seasoned, sawn timber per tonne.

Strength groups. S3 unseasoned, SD4 seasoned.

Stress grades. F8, F11, F14, F17 (unseasoned); F11, F14, F17, F22 (seasoned) when visually stress-graded in accordance with AS 2082-2000, Timber - hardwood - visually stress-graded for structural purposes.

Joint groups. JD2 seasoned.

Shrinkage to 12% MC. Shrinkage rates varies considerably between species.

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. Untreated sapwood is susceptible to lyctine borer attack.

Termite resistance. Not resistant.

Preservation. Sapwood readily accepts preservative impregnation.

Seasoning. Care required when drying to avoid splits, checks and distortion.

Hardness. Hard (rated 2 on a 6 class scale) in relation to resistance and ease of working with hand tools.

Machining. Resinous material gums up cutting edges, otherwise relatively easy to machine and turn.

Fixing. Pre-boring recommended when nailing.

Gluing. As with most high-density species, machining and surface preparation should be done immediately before gluing.

Finishing. Satisfactory in relation to painting, staining and polishing.

Uses

Engineering. Heavy engineering.

Construction. Framing, flooring, linings, joinery, fencing.

Decorative. Turnery.

Others. Boat building, vats, casks.

Identification features

General characteristics

Sapwood. Well-defined and paler than heartwood.

Heartwood. Purple red or dark red brown.

Texture. Moderately coarse, even, grain interlocked, hard to cut across end grain; end cut generally shiny; with a degree of lustre on a dressed surface.

Wood structure

Vessels. Mostly solitary with a few radial or oblique groups, medium size, even and diffuse distribution. Tyloses numerous. Vessel lines present.

Parenchyma. Apotracheal - consisting mainly of irregular spaced bands and occasional short tangential lines or diffuse strands. Paratracheal - often as incomplete vasicentric strands around the vessels, barely visible by hand lens, scant to well-defined aliform.

Rays. Fine, generally inconspicuous on the radial surface.

Other features

Burning splinter test. A match size splinter burns to a charcoal.

Intercellular canals. Generally filled with white resin, smaller than the vessels, arranged in concentric formation.

Further reading

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 04 August 2010