Merbau

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.

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).