Mersawa


INTRODUCTION

The Standard Malaysian Name for the timber of Anisoptera spp. (Dipterocarpaceae). The common vernacular names applied include kijal (Terengganu), loh (Pahang), medang sawa (Peninsular Malaysia), mersawa (Peninsular Malaysia and Sarawak) with various epithets, pengiran (Sabah) with various epithets, rengkong (Pahang), sanai (Peninsular Malaysia), sepah petri (Negeri Sembilan) and terbak (Kedah, Perlis and Kelantan). Major species include A. costata, A. curtisii, A. grossivenia, A. laevis, A. marginata, A. megistocarpa and A. scaphula. The sapwood is not sharply defined from the heartwood, which is light to dark yellow and darkens on exposure.  

Also known as Anisoptera (Australia); Mersawa (Brunei); Phdiek, Trabak and Ven ven (Cambodia); Ketimpun, Masegar, Mersawa and Mersawa daun lebar (Indonesia); Bak and Mai Bak (Laos); Boilam, Kaban, Kaban thangyin and Kaunghmu (Myanmar); Garawa (Papua New Guinea); Afu, Dagang, Dagum and Palosapis (Philippines); and Kabak, Krabak, Kra-Bark, Pik and Tabak (Thailand).


DENSITY

The timber is a Light Hardwood with a density of 515-735 kg/m3 air dry.


NATURAL DURABILITY

Untreated specimens of A. marginata of size 50 mm x 50 mm x 600 mm were planted at the test site at the Forest Research Institute Malaysia (FRIM). The timber lasted only 5 years, thus is classified as moderately durable under exposed conditions. It is very susceptible to fungal attacks. Specimens of A. laevis of size 50 mm x 50 mm x 600 mm were treated with diesel/fuel mixture and planted at the test site at FRIM in 1979. After two years, all the specimens are still sound.   


PRESERVATIVE TREATMENT

The timber is classified as difficult to treat with preservatives.   


TEXTURE

Texture is moderately coarse but even, with shallow to deeply interlocked and sometimes slightly spiral grain.


STRENGTH PROPERTIES

The timber falls into Strength Group C (Engku, 1988b) or SG 6 (MS 544:Part 2:2001).


Strength Properties of Mersawa
 

Species

Test Condition

Modulus of Elasticity(MPa)

Modulus of Rupture (MPa)

Compression parallel to grain (MPa)

Compression perpendicular to grain (MPa)

Shear strength(MPa)

A. laevis

Green

9,200

49

26

5.65

7.4

A. marginata

Green

12,600

54

28.9

5.52

7.1


MACHINING PROPERTIES

It is difficult to resaw and cross-cut and have a dulling effect on the cutters, due to the presence of silica. The timber is difficult to plane but the surface produced is smooth.


Machining Properties of Mersawa
 

Species

Test Condition

Sawing

Planing

Boring

Turning

Ripping

Cross Cutting

Ease of planing

Quality of finish

Ease of boring

Quality of finish

Ease of turning

Quality of finish

A. laevis

Green

difficult

difficult

difficult

smooth

easy

moderately smooth

-

-

Air dry

difficult

difficult

difficult

smooth

easy

rough

easy

smooth

A. marginata

Green

difficult

difficult

difficult

smooth

easy

moderately smooth

-

-

Air dry

difficult

difficult

difficult

smooth

easy

rough

easy

smooth


NAILING PROPERTY

The nailing property is rated as good.


AIR DRYING

The timber dries very slowly but with only slight degrades. Minor cupping, bowing and surface-checking are noted during drying. 13 mm thick boards take 6 months to air dry, while 25 mm and 38 mm thick boards take 7.5 and 9 months respectively.


KILN-DRYING

Kiln Schedule E is recommended. The timber dries slowly and maintains high moisture content in the core. 25 mm thick boards take approximately 16-17 days to kiln-dry from 50 to 10% moisture content.


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

48.5

55

20

155

68.0

127

53.0

45

10

170

76.5

136

58.0

40


SHRINKAGE

Shrinkage is high, radial shrinkage averaging 1.4% and tangential shrinkage averaging 3.5%.


DEFECTS

Mersawa is free from defects although some spongy heart is present in some logs. The sapwood is liable to be attacked by ambrosia beetles if the logs are left lying in the forest after felling and such attack has been known to extend to the heartwood.


USES

The timber is extremely popular as a plywood species. Other uses include light construction, door and window frames and sills (internal use only), posts, beams, joists, rafters, furniture, pallets (expendable type), packing boxes and crates, joinery, cabinet making, flooring, staircase (newel, sprandrel framing, tread, bullnose, round end and winder), tool handles (non-impact) and disposable chopsticks.


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. Lopez, D.T. 1981. Malaysian Timbers - Mersawa. Malaysian Forest Service Trade Leaflet No. 56. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 8 pp.
  3. 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.
  4. MS 544:Part 2:2001. Code of Practice for the Structural Use of Timber: Permissible Stress Design of Solid Timber.
  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.