Rubberwood

Scientific name

Hevea brasiliensis. Family: Euphorbiaceae.

Local name

Para rubber tree.

Description and natural occurrence

In its natural state, rubberwood is a large hardwood occurring in the tropical evergreen rainforests of Brazil, Bolivia and the Guianas.

Rubberwood has been planted extensively in many tropical countries to produce latex (natural rubber). At the time of felling, usually 25 years, the trees have a clear bole of more than 10 m and a diameter of 25-45 cm.

Most rubberwood is produced in Indonesia and Malaysia, the latter having two million hectares of rubber plantations and producing 45% of total world rubber production.

Wood appearance

Colour. The sapwood is not differentiated from the heartwood. The timber is whitish yellow when freshly cut and seasons to cream, straw or light brown, often with a pinkish tinge.

Grain. Straight to shallowly interlocked or wavy grain, moderately coarse but even texture.

Wood properties

Density. 640 kg/m3 at 12% moisture content; approximately 1.6 to 1.8 m3 of seasoned sawn timber per tonne.

Strength groups. (S7) unseasoned; (SD7) seasoned (brackets indicate provisional value).

Stress grades. F4, F5, F7, (unseasoned), F5, F7, F8, F11 (seasoned), when visually stress graded in accordance with AS 2082-2000, Timber - hardwood visually stress-graded for structural purposes.

Joint groups. JD3 seasoned.

Shrinkage to 12% MC. Not available.

Unit shrinkage. Not available.

Durability above-ground. Class 4 - life expectancy less than 7 years.

Durability in-ground. Class 4 - life expectancy less than 5 years.

Lyctine susceptibility. Untreated sapwood susceptible to lyctid borer attack.

Termite resistance. Not resistant.

Preservation. Sapwood readily accepts preservative impregnation, but penetration of heartwood is variable using currently available commercial processes.

Seasoning. Seasons rapidly, but prone to distortion thus requiring careful stacking and drying. Very stable in service.

Hardness. Firm (rated 4 on a 6 class scale) in relation to indentation and ease of working with hand tools.

Machining. Rubberwood is easy to saw, cross-cut, plane, turn and bore. Sharp cutting edges should be maintained to avoid ´woolliness´.

Fixing. Preboring is recommended prior to nailing.

Gluing. Glues satisfactorily.

Finishing. Will readily accept paint, stain and polish.

Uses

Construction. Flooring, internal step treads, concrete formwork, joinery.

Decorative. Panelling, balustrading, parquetry, joinery, turnery. Seen extensively in the Australian furniture market as indoor furniture e.g. dining suites, bar stools and rocking chairs.

Others. Particleboard, knife blocks, cheese boards, salad bowls, trays.

Identification features

General characteristics

Sapwood. Not differentiated from the heartwood.

Heartwood. Whitish yellow when freshly cut, darkening to cream straw or light brown on exposure, often with pink tints.

Texture. Moderately coarse but even.

Wood structure

Vessels. Small to medium size, generally arranged in short radial multiples with few solitary and occasional clusters. Vessel lines conspicuous on longitudinal face.

Resin canals. Numerous. Prominent as lines on dressed longitudinal surfaces.

Parenchyma. Distinct regularly spaced bands forming a net-like pattern with the rays.

Rays. Fine to medium, readily visible with a lens.

Other features

Deposits. Tyloses present.

Further reading

Bootle, K 2005, 'Wood in Australia: types, properties and uses', 2nd edn, McGraw-Hill, Sydney.

Hopewell, G (ed.) 2006, 'Construction timbers in Queensland: properties and specifications for satisfactory performance of construction timbers in Queensland, Class 1 and Class 10 buildings', books 1 and 2, Department of Primary Industries and Fisheries, Brisbane.

Ilic, J 1991, 'CSIRO atlas of hardwoods', Crawford House Press, Bathurst, Australia.

Standards Australia, 2000, 'AS 2082-2000: Timber - hardwood - visually stress-graded for structural purposes', Standards Australia.

Last updated 06 August 2010