BALAU, RED / SELNGAN BATU MERAH
INTRODUCTION
The Standard Malaysian Name for the heavy, red to red-brown timbers of the genus Shorea (Dipterocarpaceae). Vernacular names applied are too many to be listed here except for the more common ones, viz. balau laut merah (Peninsular Malaysia), balau merah (Peninsular Malaysia), damar laut merah (Peninsular Malaysia), membatu (Peninsular Malaysia), red selangan batu (Sabah and Sarawak), selangan batu merah (Sabah and Sarawak), semayur (Sarawak), seraya (Peninsular Malaysia) and seraya batu (Peninsular Malaysia). Major species include S. collina, S. guiso, S. inaequilateris, S. kunstleri and S. ochrophloia. The sapwood is pink, purple-brown or grey-brown and is fairly distinct from the heartwood, which is light to deep red-brown.
Also known as Selangan merah (Brunei); Balau merah and Gisok (Indonesia); Mai si khao (Laos); Guijo (Philippines); Chan, Lantan and Teng-tani (Thailand); and Chai (Vietnam).
DENSITY
The timber is a Heavy Hardwood with a density of 800-880 kg/m3 air dry.
NATURAL DURABILITY
The timber is moderately durable under exposed conditions (lasting from 2 to 5 years). The timber is subject to subterranean termite and fungal attacks.
PRESERVATIVE TREATMENT
Both S. guiso and S. ochrophloia have been found to be very difficult to treat with preservatives.
TEXTURE
Texture is moderately fine to slightly coarse and even, with deeply interlocked grain.
STRENGTH PROPERTIES
The timber falls into Strength Group A (Engku, 1988b) or SG 3 (MS 544:Part 2:2001).
| Strength Properties of Red Balau | ||||||
|---|---|---|---|---|---|---|
| Species | Moisture Content (%) | Modulus of Elasticity(MPa) | Modulus of Rupture (MPa) | Compression parallel to grain (MPa) | Compression perpendicular to grain (MPa) | Shear strength(MPa) |
| S.guiso | Green | 13700 | 94 | 43.6 | 5.52 | 10.1 |
| Air dry | 14,800 | 100 | 55.2 | 5.52 | 12.0 | |
| S.kunstleri | Green | 19,000 | 105 | 57.9 | 7.03 | 9.3 |
| Air dry | - | - | - | - | - | |
| S.ochrophloia | Green | 15,900 | 85 | 43.7 | - | 10.1 |
| Air dry | 17,000 | 99 | 55.3 | - | 9.9 | |
MACHINING PROPERTIES
It is easy to difficult to saw and work, although planing is easy and the surface produced is smooth to slightly rough.
| Machining Properties of Red Balau | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Species | Test Condition | Sawing | Planing | Boring | Turning | ||||
| Rip-sawing | Cross Cutting | Ease of planing | Quality of finish | Ease of boring | Quality of finish | Ease of turning | Quality of finish | ||
| S. guiso | Green | easy | easy | easy | smooth | easy | smooth | - | - |
| Air dry | slightly difficult | slightly difficult | easy | slightly rough | easy | smooth | moderately easy | moderately smooth | |
| S.kunstleri | Green | easy to difficult | slightly difficult | easy | smooth | easy | smooth | - | - |
| Air dry | difficult | slightly difficult | easy | smooth | slightly difficult | smooth | easy | smooth | |
| S.ochrophloia | Green | slightly difficult | easy | easy | slightly rough | easy | slightly rough | - | - |
| Air dry | slightly difficult | easy | easy | slightly rough | moderately easy | slightly rough | difficult | smooth to rough | |
NAILING PROPERTY
Nailing property varies according to species; S. guiso is reported to be excellent, while S. ochrophloia is good and S. kunstleri is poor.
AIR DRYING
The seasonig properties of some of the species tested are summarised below:
| Species | Time to air dry (months) | Remarks | |
|---|---|---|---|
| 13 mm thick boards | 38 mm thick boards | ||
| S.guiso | 4 | 6 | Fairly slow drying; moderate end-checking; slight cupping, splitting, surface-checking, insect attacks and staining. |
| S.kunstleri | 4 | 6 | Fairly slow drying; moderate end-checking; slight splitting and surface-checking. |
| S.ochrophloia | 3 | 5 | Fairly slow drying; moderate end-checking; slight splitting and surface-checking. |
KILN-DRYING
Kiln Schedule G is recommended.
| Kiln Schedule G | |||||
|---|---|---|---|---|---|
| Moisture Content (%) | Temperature (Dry Bulb) | Temperature (Wet Bulb) | Relative Humidity (%) (approx.) | ||
| °F | °C | °F | °C | ||
| Green | 120 | 48.5 | 115 | 45.0 | 85 |
| 60 | 120 | 48.5 | 113 | 45.0 | 80 |
| 40 | 130 | 54.5 | 123 | 50.5 | 80 |
| 30 | 140 | 60.0 | 131 | 55.0 | 75 |
| 25 | 160 | 71.0 | 146 | 63.5 | 70 |
| 20 | 170 | 76.5 | 147 | 64.0 | 55 |
| 10 | 180 | 82.0 | 144 | 62.5 | 40 |
SHRINKAGE
The shrinkage of red balau is summarised below:
| Species | Shrinkage (%) (Green to air dry) | Remarks | |
|---|---|---|---|
| Radial | Tangential | ||
| S.guiso | 1.6 | 3.6 | High shrinkage |
| S.kunstleri | 2.2 | 3.3 | High shrinkage |
| S.ochrophloia | 1.4 | 3.2 | High shrinkage |
DEFECTS
The logs are generally free from defects.
USES
The timber is suitable for heavy construction under cover, beams, posts, joists, rafters, pallets (heavy duty), columns (heavy duty), tool handles (impact), joinery, cabinet making, fender supports, vehicle bodies (framework and floor boards), ship and boat building (keels, keelsons and framework), plywood, heavy duty furniture, flooring (heavy traffic), door and window frames and sills, staircase (carriage, angle block, rough bracket, riser, tread, bullnose, round end, winder, stringer and newel), cooling tower (structural members), railway sleepers (treated) as well as telegraphic and power transmission posts and cross arms (treated).
REFERENCES
- Engku Abdul Rahman Chik. 1988b. Basic And Grade Stresses For Some 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 Red Balau. Malaysian Forest Service Trade Leaflet No. 45. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 7 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 Insitute Malaysia, Kuala Lumpur. 48 pp.
- MS 544: Part 2: 2001: Code Of Practice For 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 Record No. 30. Forest Research Institute Malaysia Kuala Lumpur. 201 pp.