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Keruing

Scientific name

Dipterocarpus species. Family: Dipterocarpaceae

Other names

Bagac; Apitong, Hagokhak, Panau (Philippines); Dan (Vietnam); Yang, Eng (Thailand); Kerunwing, Kruen, Kurjun, Klalar, Lagan (Indonesia)

Description

  • Keruing is the name given to timber from 70 or so species of the genus Dipterocarpus.
  • Large hardwoods with some species growing to 70m high.

Occurrence

  • Indonesia
  • Malaysia
  • Philippines
  • Sabah
  • Sarawak
  • Brunei
  • Pakistan
  • India
  • Burma
  • Borneo
  • Thailand
  • Sri Lanka
  • Kampuchea

Appearance

Colour

  • Variations between species include deep pink, orange-pink, purple-red.
  • Sapwood is usually lighter in shade and may have yellow or greyish tinges.
  • Wood darkens with age.

Grain

  • Grain is generally straight but may be slightly interlocked giving some stripe figure (pattern) on the radial surface
  • Texture varies between species, and area of origin, from fine to coarse but even.

Uses

  • Construction: laboratory flooring (has good acid resistance), internal flooring, protected framing and boards.
  • Decorative: internal joinery and mouldings, lining, panelling.
  • Others: framework of carriages and wagons.

Properties

  • Density: 790kg/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: S3 unseasoned, SD3 seasoned.
  • Joint groups: J2 unseasoned, JD2 seasoned.
  • Shrinkage to 12% MC: shrinkage varies between species but averages about 7.0% (tangential), 3.5% (radial).
  • Unit shrinkage: not available.
  • Durability above-ground: Class 3 (life expectancy 7—15 years).
  • Durability in-ground: Class 4 (life expectancy less than 5 years).
  • Lyctine susceptibility: untreated sapwood susceptible to lyctine borer attack.
  • Termite resistance: not resistant.
  • Preservation: moderately resists impregnating with preservatives, which may cause uneven distribution of preservative.
  • Seasoning: difficult to season without degrade causing checks, splits and warping; pre-steaming before drying can reduce degrade.
  • Hardness: moderately hard (rated 3 on a 6-class scale) to indent and work with hand tools.
  • Machining: silica and resin in the timber can make machining difficult; keep cutting edges sharp, and use tungsten-tipped tools for best results.
  • Fixing: nails satisfactorily; timber may stain with iron fastenings.
  • Gluing: gluing qualities vary.
  • Finishing: timber with high resin content has a poor base for all finish coatings; less resinous timber finishes satisfactorily.

Identification features

General characteristics

  • Sapwood: grey-brown, distinct from heartwood.
  • Heartwood: red-brown to dark brown.
  • Texture: moderately coarse, uniform, straight grain.

Wood structure

  • Growth rings: absent.
  • Vessels: predominantly solitary, large, visible to the naked eye, uniform diffuse distribution; heavily tylosed in some species, but not in others.
  • Parenchyma (soft tissue): apotracheal and paratracheal—apotracheal as scattered or confluent patches containing vertical resin canals; paratracheal very sparse as borders to vessels, often distinct.
  • Rays: 2 distinct sizes—medium and small; medium is visible to the naked eye, and quite prominent on radial surfaces.

Other features

  • Burning splinter test: wood burns to an ash.
  • Intercellular canals: common and prominent; size varies; arrangement is diffuse or in short tangential lines with 2–7 canals in a series.

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.