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TENGKURUNG (Blumeodendron tokbrai)
Trade Name
Tengkurung
Scientific Name
Blumeodendron tokbrai (Blume) J.J. Smith
Family
EUPHORBIACEAE
Common Names
Keterung (Indonesia); Ki kukuran (Indonesia); Tokbrai (Indonesia); Gaham badak (Malaysia)
Scientific Name Synonyms
Blumeodendron vernicosum (Hook. f.) Gage.; Blumeodendron elateriospermum J.J. Smith; Blumeodendron borneense Pax & K. Hoffm.
Description Of The Tree
Botanical Description
It is a dioecious, small to medium-sized or rarely large tree up to 35 m tall. The bole is usually straight, up to 120 cm but generally 40-50 cm in diameter, sometimes fluted or with small buttresses, occasionally stilt-rooted in peat-swamp forest.
Natural Habitat
Blumeodendron is found in primary or secondary forests, generally at low altitudes, but it has been reported up to 2,700 m of altitude.
Wood Identification
Anatomic Description Of Wood
Wood diffuse porous. Vessels per mm2 5 to 20. Occasionally vessels per mm2 less than 6. Simple perforation plates. Intervessel pits large, 10 micras or more. Apotracheal axial parenchyma diffuse and/or diffuse in aggregates. Occasionally apotracheal axial parenchyma diffuse and/or diffuse in aggregates. Occasionally paratracheal axial parenchyma scanty and/or vasicentric. Prismatic crystals in chambered axial par Rays more than 10 per mm (abundant). Occasionally rays of two distinct sizes. Ray height more than 1 mm. Occasionally larger rays more than 4 seriate. Occasionally sheath cells. Occasionally aggregated rays. Prismatic crystals in radial alignment in procumbent Occasionally fibers with distinctly bordered pits.
Availability
Cites Status
Unrestricted
General Wood Description
Color
The heartwood is pale yellow-brown or straw-brown with a slight pink tinge, not clearly differentiated from the sapwood.
Grain
The grain is usually straight, sometimes slightly interlocked.
Texture
Texture is usually moderately coarse.
Natural Durability
The wood is non-durable, with an average service life of 1.5 years in a graveyard test in Malaysia.
Natural durability index (1= Very high durability, 7=Vey low durability)
5
Resistance To Impregnation
This species is easy to treat with preservatives.
Wood Physical Properties
Basic Density or Specific Gravity (O.D. weight/vol. green) (g/cm³)
0.65
Air-dry Density (Weight and volume at 12%MC) (g/cm³)
0.73
Total shrinkage Tangential (Saturated to 0%MC) (%)
8.8
Total shrinkage Radial (Saturated to 0%MC) (%)
4.7
Drying Defects
Ease of Drying: Air seasoning is reported to be slow. Quarter sawing is recommended to minimize surface checking. In Indonesia it takes 3 months to season 20 mm thick boards from 40% to 14% moisture content. Drying Defects: Risk of surface checking. Kiln Schedules: The recommended kiln schedule is a temperature of 35 to 65 degrees with a corresponding relative humidity of 70% to 30%.
Recommended Dry Kiln Schedule
UK-K
Dimensional stability ratio (Total Tangential Shrinkage %/Total Radial Shrinkage %)
1.9
Wood Chemical Properties
Wood Mechanical Properties
Bending Strength (MOR),12%MC (kgf/cm²)
968
Stiffness (MOE) 12%MC (kgf/cm²)
143985
Compression parallel to fiber 12%MC (kgf/cm²)
428
Compression perpendicular to fiber 12%MC (kgf/cm²)
41
Shear strength radial 12%MC (kgf/cm²)
122
Janka hardness (end grain) 12%MC (kgf)
571
Workability
Blunting Effect
It is considered to have a moderate blunting effect on the cutting elements.
Machining
Machining operations are rather easy.
Planing
Planing is easy, but some grain picking up is reported.
Boring
Boring of this species is reported to be easy.
REFERENCED USES
End Uses Summary
HOUSING GENERAL, shutter boards
General Housing
- 10 - Silica in Timbers
Shutter Boards
- 20 - Prospect: The wood database
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