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Keruing

Keruing vary in colour from pinkish-brown to dark brown heartwood, often with a purple tint. The grain is straight to shallowly interlocked, and texture is moderately coarse but even. Some species contain oleo-resin which excudes, especially on the end grain.

 

Scientific Name: Dipterocarpus

 

Preferred Common Names: Keruing

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Discription

 

There are more than seventy species of this genus in South East Asia. In general the timbers of the different species are very similar. The trees vary from 30 to 60m in height with a clear bole up to 21m with a breast height diameter of 1 to 1.8m.

The heartwood is pinkish-brown to dark brown and well defined from the grey sapwood. The texture is moderately coarse and even, the grain straight or interlocked.

The timber dries slowly, even at high temperatures and is inclined to distort and to develop end-splits. Resin exudation is common. The timber generally saws well, but silica causes rapid dulling of cutting tools, therefore tungsten carbide-tipped saws are recommended for dry timber. Nailing is satisfactory but glueing is sometimes difficult. The finish, like the other working qualities, depends on the resin content of the species. Durability and resistance are moderate.

The Sapwood is grey in colour and distinct, often containing evidence of wood borer attack. The heartwood varies from a pinkish brown through to a dark brown. The grain is coarse, open, interlocked but fairly even; and typically covered with a resinous exudation that is sticky to the touch.

Uniform drying can be slow and difficult to achieve in a kiln. It will cup badly and distort generally; resins present will end up as hard globules over all surfaces! Even when air-dried, Keruing is not particularly stable; it responds by expanding and contracting with the seasons. Sawing Keruing can be difficult; the saw's teeth tend to clog up with resinous deposits and need cleaning regularly. A slightly fibrous finish is usual when planed, and once more the resin can be a problem. Keruing is easy to split, so pre-drill everything before nailing or screwing.

A medium to heavyweight timber, Keruing has found many uses in the construction applications. Not one of the best timbers for joinery.

Any location that is exposed to sunlight should be avoided, as the resin will continue to come out even through painted or finished surfaces. High temperatures will cause resin exudation, Distortion, especially cupping, is considerable and slight collapse may occur.

There is high shrinkage in drying and large movement in service.

Uses

  • Deck substructures

  • Frame and hull work for boats

  • Sleepers

  • Fencing

  • Poles

Properties

Dry Mass per kg

 

Modulus of rupture

 

Fibre stress at P.L. (Point Load)

 

Modulas of elastisity

 

Compresstion parallel to grain

 

Compression perpendiccular to grain

 

 

 

Shear parallel to grain

 

Impact Bending

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750 kg/m3 (Wet density 850 - 950 kg/m3)

 

113 MPa

78 MPa

 

19190 MPa

 

65.2 MPa (Maximum crushing strengh)

 

14.7 MPa (Stress at 2.54mm deflection)

 

7.2 MPA (Stress at Point Load)

 

10.1 MPa (Maximum shearing strengh)

32.8 MPa (Toughness)