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 575-735 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 | ||||
| Re-sawing | 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.
| FKiln Schedule J | |||||
|---|---|---|---|---|---|
| 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
- 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.
- 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.
- 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.
- MS 544:Part 2:2001. Code of Practice for the Structural Use of Timber: Permissible Stress Design of Solid Timber.
- 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.