Kempas

Scientific name

Koompassia spp. principally K. malaccensis, K. excelsa. Family: Leguminosae.

Local names

Impas (Sabah), tualang (Malaysia), tapang, kayu raja, mengris (Sarawak), manggis (Philippines), oempas (Sumatra), ginoo (Palawan), mengaris (Borneo)

Description and natural occurrence

K. excelsa is a very large tree attaining 60 m in height, with high, wide-spreading buttresses and a clean, columnar bole with little taper. The bark is smooth, corky and grey in colour. K. malaccensis is usually smaller, up to 50 m tall, and more slender in form.

Species of kempas occur through Borneo, Malaysia, the Philippines, Indonesia and Papua New Guinea.

Wood appearance

Colour. Heartwood pink when freshly cut, darkening to a deep orange-brown to red brown after exposure. Sapwood pale yellow to pink-brown and distinct from heartwood.

Grain. Grain is interlocked, spiral or wavy. Texture coarse and even, except when zones of included phloem (bark) present.

Wood properties

Density. 880 kg/m3 at 12% moisture content; approximately 1.1 m3 of seasoned sawn timber per tonne.

Strength groups. S2 unseasoned; SD2 seasoned.

Stress grades. F11, F14, F17, F22 (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. J3 unseasoned; JD2 seasoned.

Shrinkage to 12% MC. Approximately 3% (tangential); 2% (radial).

Unit shrinkage. Not available

Durability above-ground. Class 3 - life expectancy 7 to 15 years.

Durability in-ground. Class 3 - life expectancy 5 to 15 years.

Lyctine susceptibility. Untreated sapwood susceptible to lyctid borer attack.

Termite resistance. Not resistant.

Preservation. Sapwood readily accepts preservative impregnation.

Seasoning. Included phloem (bark) causes the timber to split during drying, but clean material seasons well if care taken.

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

Machining. Interlocking grain can cause difficulty, as does the fibrous nature of kempas. Difficult to work with hand tools.

Fixing. Pre-boring advisable when nailing close to edges. The timber is slightly acidic and may corrode iron fastenings.

Gluing. Can be satisfactorily bonded using standard procedures.

Finishing. Kempas can be sanded to a good finish but requires filling prior to polishing. Stains and accepts paint satisfactorily.

Uses

Decorative. Parquetry flooring, panelling, furniture, shop fitting.

Others. Used for railway sleepers, poles, posts in South-East Asia, but not recommended for these applications for long-term use in Australia. Plywood, flooring, decking (but see the note below). Walking sticks, charcoal, shingles, chemical vats, cargo handling pallets.

Note: Stock containing included phloem (bark) has reduced strength and will split when exposed to the weather, making it unsuitable for some applications, such as exposed decking.

Identification features

General characteristics

Sapwood. Pale yellow to pink-brown, distinct from the heartwood.

Heartwood. Orange-brown to red brown.

Texture. Coarse and even, grain variable but rarely straight.

Wood structure

Growth rings. Indistinct.

Vessels. Diffuse porous arrangement, few in number, medium sized to moderately large, solitary or in radial groups of 2 to 3. Deposits frequently present.

Parenchyma. Aliform and confluent.

Rays. Fine, barely visible with the naked eye.

Other features

Burning splinter test. Match size splinter burns to a full white ash.

Ripple marks. Present.

Further reading

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.

Last updated 27 August 2010