Kapur

Kapur

INTRODUCTION

The Standard Malaysian Name for the timber of Dryobalanops spp. (Dipterocarpaceae). Vernacular names applied to this timber include kapur(Peninsular Malaysia, Sabah and Sarawak) with various epithets, keladan (Peninsular Malaysia) and kelansau (Sarawak). Major species include D. aromatica, D. beccarii,D. keithii, D. lanceolata, D. oblongifolia and D. rappa. The sapwood is yellowish brown and sharply defined from the heartwood, which is reddish brown.

DENSITY

The timber is a Medium Hardwood with a density of 580-820 kg/m³ air dry.

NATURAL DURABILITY

Standard graveyard test of untreated D. aromatica and D. oblongifolia specimens of dimension 51 mm x 51 mm x 610 mm had been conducted in the Forest Research Institute Malaysia (Jackson, 1965). From the studies conducted, the average service life of D. oblongifolia and D. aromatica were 1.9 and 6.0 years respectively. It can be seen that there is a remarkable difference in the natural durability of these two species and based on the weakest species, kapur is therefore classified as not durable. It is known that these two species are resistant to fungal attack, but are susceptible to termite attack.

PRESERVATIVE TREATMENT

The timber is not amenable to preservative treatment and it is classified as difficult to treat.

TEXTURE

Texture is moderately coarse and even with straight or shallowly interlocked or sometimes deeply interlocked grain.

STRENGTH PROPERTIES

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

Strength Properties of Kapur

Species	Test condition	Modulus of Elasticity (MPa)	Modulus of Rupture (MPa)	Compression parallel to grain (MPa)	Compression perpendicular to grain (MPa)	Shear strength (MPa)
D. aromatica	Green	15,900	84	46.5	4.2	8.4
	Air dry	18,700	114	61.7	5.5	10.5
D. oblongifolia	Green	13,200	73	39.2	5.1	8.1
	Air dry	-	-	-	-	-

MACHINING PROPERTIES

The timber of D. rappa is easy to work while the other species range from moderately easy to slightly difficult.

Sawing and Woodworking Properties of Kapur

Species Tested	Test Condition	Sawing		Planning		Boring		Turning
		Re-sawing	Cross-Cutting	Ease of planing	Quality of finish	Ease of boring	Quality of finish	Ease of turning	Quality of finish
D.  aromatica	Green	moderately easy	easy	easy	moderately smooth	easy	smooth	-	-
	Air dry	easy	easy	easy	moderately smooth	easy	smooth	easy	moderately smooth
D. oblongifolia	Green	easy to slightly difficult	easy	easy	rough	easy	smooth	-	-
	Air dry	slightly difficult	easy	easy	smooth	easy	smooth	easy	moderately smooth

NAILING PROPERTY

Nailing property is good in D. rappa and poor in the other species.

AIR DRYING

The timber dries moderately slowly to slowly with little degrade. The seasoning properties of some species are summarised below:

Species	Time to air dry (months)		Remarks
	13 mm thick boards	38 mm thick boards
D. aromatica	2	5	Fairly slow drying; moderate end-splitting; splitting and surface-checking.
D. rappa	4	6	Slow drying; moderate cupping due to very high differential shrinkage.

KILN-DRYING

Kiln Schedule E is recommended. Care must be taken to stack the timber properly as there is a strong tendency to cup. 25 mm thick boards are expected to kiln-dry in 14 days.

Kiln Schedule E

Moisture Content (%)	Temperature (Dry Bulb)		Temperature (Wet Bulb)		Relative Humidity (%) (approx.)
	F	C	F	C
Green	120	48.5	115	46.0	85
60	120	48.5	113	45.0	80
40	125	51.5	116	46.5	75
30	130	54.5	117	47.0	65
25	140	60.0	120	49.0	55
20	155	68.0	127	53.0	45
15	170	76.5	136	58.0	40

SHRINKAGE

The shrinkage of some species are summarised below: 

Species	Shrinkage (%) (Green to air dry)		Remarks
	Radial	Tangential
D. aromatica	2.1	4.6	Very high shrinkage.
D. oblongifolia	1.7	3.8	High shrinkage.
D. rappa	1.5	5.1	Very high differential shrinkage.

 DEFECTS

The most common defect that is associated with the timber is the pin-holes. It was reported that the pin-holes are more frequently found in D. aromatica than in D. oblongifolia (Desch, 1941). The pin-holes are caused by one of the small ambrosia beetles. The attack usually begins in the living tree and the attack cannot continue in seasoned wood. Spongy heart may occur in logs but the presence is usually insignificant. 

USES

The timber is suitable for medium construction, posts, beams, joists, rafters, door and window frames and sills, fender supports, telegraphic and power transmission posts and cross arms, flooring, staircase (treads, angle blocks, rough brackets, bullnose, riser, balustrade, carriage, stringers, round end and winder), vehicle bodies (frame-work, floor boards and planking), ship and boat building (keels, keelsons and framework), pallets (heavy and permanent types), tool handles (impact), cooling tower (structural members), plywood, laboratory benches, column (light duty) and railway sleepers. In domestic flooring and internal fittings where finished appearance is important, care should be taken in fixing because of a tendency to develop an unsightly black stain in contact with iron nails, screws or other fittings.