The Standard Malaysian Name as well as the ASEAN Standard Name for the timber of Upuna borneensis (Dipterocarpaceae). Vernacular name applied includes upun (Sabah). Only one species has been recorded, viz. U. borneensis. The sapwood is lighter in colour and is distinctly differentiated from the heartwood, which is dark brown.
Also known as Upun batu (Brunei); and Balau penyau, Cangal tanduk and Penyau tanduk (Indonesia).
The timber is very hard and very heavy with a density of 945-1,040 kg/m3 air dry. The timber is classified under Heavy Hardwood in Malaysia.
The timber is very durable under exposed conditions.
It is extremely resistant to preservative treatment.
Texture is fine to moderately fine but even, with straight to shallowly interlocked grain.
The timber falls into Strength Group A (Burgess, 1958) or SG3 (MS 544:Part 2:2001).
It is slightly difficult to saw due to its hardness and resinous nature. Planing is easy and the surface is generally smooth although there is a slight pick-up of grain in radially sawn material.
The nailing property is rated as poor.
The timber seasons moderately slowly, with very minor seasoning defects except for some insect damage. 13 mm thick boards take approximately 3 months to air dry, while 38 mm thick boards take 4 months.
Shrinkage is fairly high, with radial shrinkage averaging 1.8% and tangential shrinkage averaging 2.9%.
The timber is suitable for all forms of heavy construction, heavy duty furniture, flooring (heavy traffic), railway sleepers and power transmission poles, if sufficient lengths can be obtained.
Burgess, H. J. 1958. Strength Grouping of Malaysian Timbers. Malayan Forest Service Trade Leaflet No.25. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 15 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.