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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.

 




All Copyright 2008 Reserved By Chea Sa Timber Sdn. Bhd.
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All Copyright 2008 Reserved By Chea Sa Timber Sdn. Bhd.
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