Merbau


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).


USES

Merbau is a very attractive wood, with its growth ring figure and deep colour. The timber is suitable for interior finishing, panelling, mouldings, office fittings, flooring (heavy traffic), superior joinery, cabinet-making, musical instruments, ornamental items and carvings. The timber is widely used for the manufacture of reproduction antique furniture and strip flooring in the country. It is also suitable for heavy construction, power transmission poles, railway sleepers, decking, columns (heavy duty), door and window frames and sills, fender supports, staircase (apron lining, rough bracket, baluster, balustrade, carriage, handrail, newel, riser, stringer, tread, bullnose, round end and winder), heavy duty furniture, tool handles (impact) and pallets (heavy permanent type).


REFERENCES

  1. Engku Abdul Rahman Chik. 1998b. Basic and Grade Stresses for Strength Groups of Malaysian Timbers. Malayan Forest Service Trade Leaflet No. 38. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 13 pp.
  2. Foxworthy, F. W. & Woolley, H. W. 1930. Durability of Malayan Timbers. Mal. For. Rec. No. 8.
  3. Jackson, W. F. 1965. The Durability of Malayan Timbers. Malaysian Forest Servive Trade Leaflet No. 28.
  4. Menon, K. D. 1958. Susceptibility of Commercial Species of Malayan Timbers to Powder-post Beetle Attack. Malaysian Forest Servive Trade Leaflet No. 27.
  5. Menon, P. K. B. 1986. Uses of Some Malaysian Timbers. Revised by Lim, S. C. Timber Trade Leaflet No. 31. The Malaysian  Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 48 pp.
  6. MS 544:Part 2:2001. Code of Practice for the Structural Use of Timber: Permissible Stress Design of Solid Timber.
  7. Ser, C. S. 1982. Malaysian Timbers - Merbau. Malaysian Forest Service Trade Leaflet No. 65. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kepong. 5 pp. 
  8. Wong, T. M. 1982. A Dictionary of Malaysian Timbers. Revised by Lim, S. C. & Chung, R. C. K. Malayan Forest Records No. 30. Forest Research Institute Malaysia, Kuala Lumpur. 201 pp.