Chengal

Scientific name

Balanocarpus heimii. Family: Dipterocarpaceae

Local names

Penak, chengai

Description and natural occurrence

Chengal is a straight-boled, large hardwood attaining 25 m in height on good sites. It occurs in peninsular Malaysia in a wide range of conditions from low-lying swamp flats to hills at 10,000 m. It also has a limited occurrence in Thailand.

Wood appearance

Colour. Sapwood is pale yellow and well defined. Heartwood is yellow to dark brown, often with a green tinge.

Grain. Grain is usually slightly interlocked producing a vague ribbon figure on the radial face. Chengal has an even, medium texture.

Wood properties

Density. 930 kg/m3 at 12% moisture content; approximately 1.0 m3 of seasoned sawn timber per tonne.

Strength groups. S1 unseasoned; SD2 seasoned.

Stress grades. F14, F17, F22, F27 (unseasoned), F17, F22, F27, F34 (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. 6.3% (tangential); 1.0% (radial).

Unit shrinkage. Not available.

Durability above-ground. Class 1 - life expectancy over 40 years.

Durability in-ground. Class 1 - life expectancy over 25 years.

Lyctine susceptibility. Sapwood is not susceptible to lyctine borer attack.

Termite resistance. Resistant.

Preservation. Sapwood moderately resistant to preservative treatment.

Seasoning. Chengal is a slow seasoning timber with very low shrinkage and dries with minimal degrade.

Hardness. Hard (rated 1 on a 6 class scale) in relation to resistance to indentation and ease of working with hand tools.

Machining. Works well for a high-density timber except for the presence of resin. A cutting angle of 20° recommended on interlocked, quarter-sawn material to prevent ´picking-up´.

Fixing. Pre-drilling recommended prior to nailing.

Gluing. Due to high density, machining and surface preparation should be done immediately prior to gluing.

Finishing. Care needed due to presence of resin. A good finish can be obtained.

Uses

Engineering. Used for structural members requiring high strength and durability, railway sleepers, wharf and bridge constructions, poles, piles, mining timbers.

Construction. Heavy duty flooring, decking.

Others. Boat building, truck bodies, casks, vats, churns.

Identification features

General characteristics

Sapwood. Well defined from heartwood.

Heartwood. Dark tan-brown, planed surface lustrous, sometimes with subdued strip figure.

Texture. Moderately fine and even texture, interlocked grain, hard to cut across the grain.

Wood structure

Vessels. Medium size, predominantly solitary, others in radial pairs or short multiples, evenly distributed. Filled with tyloses.

Parenchyma. Numerous short fine apotracheal strands and tangential lines closely spaced, often not clearly visible with hand lens.

Rays. Moderately fine, inconspicuous on a radial surface.

Ripple marks. Characteristic and very distinct.

Intercellular canals. Vertical canals, smaller than vessels, filled with white resin, in concentric formation and often discontinuous.

Other features

Burning splinter test. A match size splinter burns to ash.

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