Merpauh


INTRODUCTION

The Standard Malaysian Name for the timber of Swintonia spp. (Anacardiaceae). Vernacular names applied include merpauh (Peninsular Malaysia) with various epithets, periang (Peninsular Malaysia), pitoh (Sarawak), rengas (Sabah) and selan (Sarawak). Major species include S. floribunda var. penangiana, S. schwenkii and S. spicifera. The sapwood is light brown with a grey or pink tinge and is not sharply differentiated from the heartwood, which is light grey-brown with a pink tinge. Some trees develop a corewood, which is streaked with orange and red lines.

Also known as Kereta and Maban (Indonesia); Muom (Cambodia); Civit, Shitle and Taung-thayet (Myanmar); Civit (Pakistan); Kaluis and Lomarou (Philippines); Muom (Vietnam).


DENSITY

The timber is a Medium Hardwood with a density of 640-880 kg/m3 air dry.


NATURAL DURABILITY

Untreated specimens of merpauh measuring 50 mm x 50 mm x 600 mm achieved an average service life of 1.5 years at the testing ground at the Forest Research Institute Malaysia (FRIM). This placed the timber under the non durable category. The timber is readily attacked by insects and fungi, especially staining fungi, which discolour both the sapwood and heartwood.


PRESERVATIVE TREATMENT

Based on trials carried out on two species of merpauh, it was found that the treatability of the timber varies considerably, from very easy to average.


TEXTURE

Texture is moderately 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 Merpauh
 

Species

Test Condition

Modulus of Elasticity(MPa)

Modulus of Rupture (MPa)

Compression parallel to grain (MPa)

Compression perpendicular to grain (MPa)

Shear strength(MPa)

S. floribunda var. penangiana

Green

14,700

77.0

40.5

4.48

10.9

Air dry

16,300

103.0

51.4

7.24

12.6

S. schwenkii

Green

14,200

76.0

37.7

4.34

10.4

Air dry

15,700

97.0

47.7

6.41

13.4

S. spicifera

Green

16,800

80.0

39.7

-

13.2

Air dry

18,100

108.0

56.6

-

13.3


MACHINING PROPERTIES

It is difficult to very difficult to saw and cross-cut but is easy to plane and the surface produced is smooth.


Machining Properties of Merpauh 

Species

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

S. floribunda var. penangiana

Green

difficult

difficult

easy

smooth

difficult

smooth

-

-

Air dry

very difficult

very difficult

easy

smooth

difficult

smooth

difficult

slightly rough

S. schwenkii

Green

moderately easy

moderately easy

easy

smooth

difficult

smooth

-

-

Air dry

difficult

very difficult

easy

smooth

very difficult

smooth

difficult

rough

S. spicifera

Green

very difficult

very difficult

easy

smooth

very difficult

smooth

-

-

Air dry

very difficult

very difficult

easy

smooth

slightly difficult

smooth

difficult

rough


NAILING PROPERTY

The nailing property ranges from good to very poor depending on species.


AIR DRYING

The seasoning properties of some species tested are summarised below:

Species

Time to air dry (months)

Remarks

13 mm
thick boards

38 mm thick boards

S. floribunda var.
penangiana

2.5

3.5

Fairly fast drying; moderate staining; slight cupping, bowing, twisting and insect attacks.

S. schwenkii

2.5

4.5

Moderate fast drying; moderate staining; slight cupping, bowing, twisting, end-checks and insect attacks.

S. spicifera

2

4

Fairly fast drying; moderate staining; end-checks, slight cupping, bowing, twisting and insect attacks.


KILN-DRYING

Kiln Schedule C is recommended.


Kiln Schedule C

Moisture Content (%)

Temperature (Dry Bulb)

Temperature (Wet Bulb)

Relative Humidity (%)

F

C

F

C

Green

105

40.5

101

38.0

85

60

105

40.5

99

37.0

80

40

110

43.5

102

39.0

75

35

110

43.5

100

38.0

70

30

115

46.0

103

39.5

65

25

125

51.5

109

43.0

60

20

140

60.0

118

47.5

50

15

150

65.5

121

49.0

40


SHRINKAGE

The shrinkage of merpauh is summarised below:

Species

Shrinkage (%)
(Green to air dry)

Remarks

Radial

Tangential

S. floribunda var. penangiana

0.8

1.5

Low shrinkage

S. schwenkii

1.4

2

Average shrinkage

S. spicifera

0.9

1.8

Fairly low shrinkage


DEFECTS

Logs left in the open will sustain fairly severe attacks by insects and staining fungi. While the sapwood is very prone to stain and rot, the heartwood will be discoloured by the stain.


USES

The timber is suitable for light and medium construction under cover. The attractively streaked corewood, if available is suitable for high-class joinery and furniture. The timber is also suitable for interior finishing, panelling, mouldings, partitioning, flooring, door and window frames and sills, plywood, telegraphic and power transmission posts and cross arms, piling and railway sleepers.


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. 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.
  3. MS 544:Part 2:2001. Code of Practice for the Structural Use of Timber: Permissible Stress Design of Solid Timber.
  4. Sim, H. C. 1984. Malaysian Timbers - Merpauh. Malaysian Forest Service Trade Leaflet No. 82. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 8 pp.
  5. 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.