Properties and Uses

Tualang

The Standard Malaysian Name for the timber of Koompassia excelsa (Leguminosae). The timber is a medium hardwood with a density of 800–865 kg m^–3air dry. The sapwood is buff-coloured or yellow-brown, often with a pink tinge and is sharply differentiated from the heartwood, which is reddish brown to deep brick-red-brown when fresh and darkens with age to a deep chocolate-brown. Texture is rather coarse but even except in areas where included phloem occurs. Grain is interlocked, often deeply interlocked. The timber is very strong (Strength group A). It is easy to resaw and cross-cut when green but is slightly difficult to resaw when dry. Planing is easy in either condition and the surface produced is smooth to moderately smooth. Nailing property is rated as good. The timber dries moderately slowly to slowly with slight end-checking, surface-checking and insect attacks as the main sources of degrade. 13 mm boards take 3.5 months to air dry, while 38 mm boards take 6 months. Shrinkage is average, with radial shrinkage averaging 1.5% and tangential shrinkage averaging 1.7%. The timber is moderately durable and is highly amenable to preservative treatment.

USES: Treated, the timber is suitable for all heavy construction, like posts, beams, joists, railway sleepers and power transmission poles. Untreated, the timber is suitable for parquet and strip flooring, panelling and heavy-duty furniture.

Vernacular names applied include kayu raja (Sar.), mengaris (Sab.) and tapang (Sar.). This is a monospecific timber.