Keruing

Scientific name

Dipterocarpus species (combined group of about 70 species). Family: Dipterocarpaceae

Local names

Apitong, hagokhak, panau (Philippines), dan (vietnam), yang, eng (Thailand), kerunwing, kruen, kurjun, Klalar, lagan (Indonesia), bagac.

Description and natural occurrence

Keruing is the name given to timber from 70 or so species of the genus Dipterocarpus. They are large hardwoods, some species attaining a height of 70 m.

Keruing occurs throughout Indonesia, Malaysia, Philippines, Sabah, Sarawak, Brunei, Pakistan, India, Burma, Borneo, Thailand, Sri Lanka and Kampuchea.

Wood appearance

Colour. Heartwood varies between species but is most commonly red-brown. Variations 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 resulting in some stripe figure on the radial surface. Texture varies between species and area of origin from fine to coarse but even.

Wood properties

Density. 790 kg/m3 at 12% moisture content; approximately 1.3 m3 of seasoned sawn timber per tonne.

Strength groups. S3 unseasoned, SD3 seasoned.

Stress grades. F8, F11, F14, F17 (unseasoned), F14, F17, F22, F27 (seasoned), when visually stress graded in accordance with AS 2082-2000, Timber - hardwood - visually stress-graded for structural purposes.

Joint groups. J2 unseasoned; JD2 seasoned.

Shrinkage to 12% MC. Shrinkage varies between species but averages approximately 7.0% (tangential); 3.5% (radial).

Unit shrinkage. Not available.

Durability above-ground. Class 3 - life expectancy 7 to 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. Keruing is moderately resistant to impregnation with preservatives, resulting in a possibility of 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) in relation to indentation and ease of working with hand tools.

Machining. The presence of silica and resin can make machining difficult. Cutting edges must be kept sharp, and tungsten-tipped tools give best results.

Fixing. Nails satisfactorily; stock may stain with iron fastenings.

Gluing. Gluing qualities variable.

Finishing. Stock with high resin content has a poor base for all finish coatings. Less resinous stock finishes satisfactorily.

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.

Identification features

General characteristics

Sapwood. Grey-brown, distinct from heartwood.

Heartwood. Red brown to dark brown.

Texture. Moderately coarse, uniform, straight grain.

Wood structure

Vessels. Predominantly solitary, large, visible to the naked eye, uniform diffuse distribution. Heavily tylosed in some species, but not in others.

Parenchyma. Apotracheal and paratracheal; apotracheal as scattered or confluent patches containing vertical resin canals; paratracheal very sparse as borders to vessels, often distinct.

Rays. Of two distinct sizes; medium and small. Medium size visible to the naked eye, quite prominent on radial surfaces.

Other features

Burning splinter test. The wood burns to an ash.

Intercellular canals. Common and prominent, variable in size, arrangement diffuse or in short tangential lines with 2-7 canals in a series.

Further reading

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 03 August 2010