INTRODUCTION

The Standard Malaysian Name for the timber of Intsia spp., principally I. palembanica (Leguminosae). Vernacular names applied include merbau ipil (Peninsular Malaysia) and ipil laut (Sabah) for I. bijuga. Major species include I. bijuga and I. palembanica. The sapwood is pale yellow to light buff and is sharply differentiated from the heartwood, which is yellowish to orange-brown when fresh, darkening to brown or dark red-brown on exposure.

Also known as Kwila (Australia); Merbau (Brunei); Krakasprek (Cambodia); Vesi (Fiji); Besi kesia, Ipil, Kayu besi and Merbau (Indonesia); Tat-takun (Myanmar); Komu (New Caledonia); Bendora and Kwila (Papua New Guinea); Ipil, Ipil laut and Malaipil (Philippines); Ifilele (Samoa Islands); Lumpha, Lumphor thale, Lum-por and Maka-mong (Thailand); and Gonuo (Vietnam).

DENSITY

The timber is a Heavy Hardwood with a density of 515-1,040 kg/m3 air dry.

NATURAL DURABILITY

The timber of merbau is classified as durable under exposed conditions. The classification is based on the standard graveyard tests of untreated specimens of dimension 50 mm x 50 mm x 600 mm conducted at the Forest Research Institute Malaysia (FRIM). Two such tests were conducted on the species I. palembanica. In the first series of such tests, the average service life for 14 test specimens was 5.5 years (Foxworthy & Woolley, 1930). In the second test, the average service life for 60 specimens was 6 years (Jackson, 1965).

PRESERVATIVE TREATMENT

The timber is classified as very difficult to treat with preservatives.

TEXTURE

Texture is rather coarse but even, with interlocked grain.

STRENGTH PROPERTIES

The timber falls into Strength Group B (Engku, 1988b) or SG 4 (MS 544:Part 2:2001).

Strength Properties of Merbau

Test Condition

Modulus of Elasticity(MPa)

Modulus of Rupture(MPa)

Compression parallel to grain

(MPa)

Compression perpendicular to grain

(MPa)

Shear strength(MPa)

Green

13,900

89.0

46.7

6.4

10.8

Air dry

15,400

116.0

58.2

9.2

12.5

MACHINING PROPERTIES

It is moderately easy to resaw and cross-cut when green but is slightly difficult when dried. Planing is easy to slightly difficult and the planed surface is smooth in most cases except for slight picking up of grain on the radial face.

Machining Properties of Merbau

Test Condition

Sawing

Planing

Boring

Turning

Resawing

Cross Cutting

Ease of planing

Quality of finish

Ease of boring

Quality of finish

Ease of turning

Quality of finish

Green

moderately easy

moderately easy

easy

smooth

easy

smooth

Air dry

slightly difficult

slightly difficult

slightly difficult

smooth

easy

smooth

easy

smooth

NAILING PROPERTY

Nailing property is rated as very poor.

AIR DRYING

The timber seasons slowly without any degrade except for some powder-post-beetle attacks on the sapwood. 13 mm thick boards take approximately 4.5 months to air dry, while 38 mm thick boards take 6 months.

SHRINKAGE

Shrinkage values are particularly low. Radial shrinkage averaging 0.9% and tangential shrinkage averaging 1.6%.

DEFECTS

The logs are generally free from common defects. However, it has been reported that the timber is highly susceptible to powder-post beetle attacks (Menon, 1958).