Tualang

Scientific Name:
Koumpassia excelsa

Other Names and Species:
Dëoh
Honey Bee Tree
Kayu Rajah
Mengaris
Manggis
Menggeris
Tapang

Origin:
Southeast Asia. The Standard Malaysian Name for the timber of Koompassia excelsa (Leguminosae). Vernacular names applied include kayu raja (Sarawak), mengaris (Sabah) and tapang (Sarawak). Tualang is a monospecific timber.

Weight:
The timber is a Medium Hardwood with a density of 800-865 kg/m3 air dry.

Use:
Tualang’s many uses include flooring, furniture, railroad ties, building construction, and utility poles. Heavy construction, like posts, beams, joists, columns (heavy duty), piling, railway sleepers and power transmission poles. Untreated, the timber is suitable for flooring (heavy traffic), panelling, mouldings, heavy duty furniture, fender supports, office and shop fittings, tool handles (impact) and plywood.

General characteristic:
The sapwood of tualang is gray-white to yellowish-brown while the heartwood ranges from dark red when fresh cut, changing to a deep chocolate brown color with time. Texture is rather coarse but even except in areas where included phloem occurs. Grain is interlocked, often deeply interlocked.  Tualang has a coarse and generally even texture.

Working properties:
Tualang requires special tips (chromium-plated is suggested) or band saws to cut properly. Special nails are suggested to prevent staining. Glue requires some effort to set properly but will hold well once installed. Tualang polishes to a high, lusterous finish and holds stain well, with some filling required

Drying and shrinkage:
The timber dries moderately slowly to slowly with slight end-checking, surface-checking and insect attacks as the main sources of degrade. 13 mm thick boards take 3.5 months to air dry, while 38 mm thick boards take 6 months. Shrinkage is average, with radial shrinkage averaging 1.5% and tangential shrinkage averaging 1.7%.

Durability:

The durability rating is based on the standard graveyard tests conducted at the Forest Research Institute Malaysia (FRIM) on specimens of dimension 50 mm x 50 mm x 600 mm. In the first series of such tests, all 6 specimens were completely destroyed after 3.5 years. In the second test, 60 specimens were used and the average service life was 3 years. The sapwood of the timber is susceptible to both powder-post beetle and fungi attacks, while the heartwood is readily destroyed by termites.

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