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Kempas

Scientific name

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

Other names

Impas (Sabah); Tualang (Malaysia); Tapang, Kayu raja, Mengris (Sarawak); Manggis (Philippines); Oempas (Sumatra); Ginoo (Palawan); Mengaris (Borneo)

Description

  • K. excels:
    • very large tree growing to 60m high
    • high, wide-spreading buttresses
    • clean, columnar bole (trunk) with little taper
    • bark is smooth, corky and grey.
  • K. malaccensis:
    • usually smaller, growing to 50m tall
    • more slender in form.

Occurrence

  • Occurs throughout Borneo, Malaysia, the Philippines, Indonesia and Papua New Guinea.

Appearance

Colour

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

Grain

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

Uses

  • Decorative: parquetry flooring, panelling, furniture, shop fitting.
  • Others: railway sleepers, poles, posts in Southeast Asia, but not recommended for these applications for long-term use in Australia; plywood, flooring, decking (but refer unsuitable use below); walking sticks, charcoal, shingles, chemical vats, cargo handling pallets.
  • Unsuitable use: timber including phloem (bark) has reduced strength and will split when exposed to the weather, making it unsuitable for some uses, such as exposed decking.

Properties

  • Density: 515-545kg/m3 at 12% moisture content; about 1.8m3 of seasoned sawn timber per tonne.
  • Strength groups: G. fasciculiflora and G. leichhardtii—S6, G. dalrympleana—(S7) unseasoned, G. fasciculiflora—(SD6), G. leichhardtii—SD6, G. dalrympleana—(SD7) seasoned (brackets indicate provisional value).
  • Stress grades: G. fasciculiflora and G. leichhardtii—F4, F5, F7, F8; G. dalrympleana—F4, F5, F7 (unseasoned); G. fasciculiflora, G. leichhardtii—F7, F8, F11, F14; G. dalrympleana—F5, F7, F8, F11 (seasoned) when visually stress-graded according to AS 2082—2000: Timber—Hardwood—Visually stress-graded for structural purposes.
  • Joint groups: J4 unseasoned, JD4 seasoned.
  • Shrinkage to 12% MC: G. leichhardtii—3.7% (tangential), 1.6% (radial).
  • Unit shrinkage: G. leichhardtii—0.26% (tangential), 0.15% (radial)—these values apply to timber reconditioned after seasoning.
  • Durability above-ground: Class (1) (life expectancy over 40 years).
  • Durability in-ground: Class 1 (life expectancy over 25 years).
  • Lyctine susceptibility: Untreated sapwood susceptible to lyctine borer attack.
  • Termite resistance: not resistant.
  • Preservation: sapwood readily impregnates with preservative, but penetration of heartwood is negligible using available commercial processes.
  • Seasoning: air seasons very slowly; requires mild schedules for satisfactory kiln drying.
  • Hardness: soft (rated 5 on a 6-class scale) to indent and work with hand tools.
  • Machining: machines well due to its slightly greasy nature.
  • Fixing: due to natural acidity, use non-corrosive fittings and fastenings.
  • Gluing: satisfactorily bonds using standard procedures.
  • Finishing: readily accepts stain, polish and paint.

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 varies but rarely straight.

Wood structure

  • Growth rings: indistinct.
  • Vessels: diffuse porous arrangement, few and medium to moderately large; solitary or in radial groups of 2–3; frequent deposits.
  • Parenchyma (soft tissue): 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.

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.
  • Queensland Government, DAF 2018, Construction timbers in Queensland: Properties and specifications for satisfactory performance of construction timbers in Queensland. Class 1 and Class 10 buildings, Books 1 & 2, Department of Agriculture and Fisheries, Brisbane.
  • Standards Australia, 2000, AS 2082—2000: Timber—Hardwood—Visually stress-graded for structural purposes, Standards Australia International, Strathfield, NSW.