Ru

INTRODUCTION

The common Malaysian name for the timbers of Casuarina spp. and Gymnostoma spp. (Casuarinaceae). The ASEAN Standard Name, which is of Philippine origin, is AGOHO. Vernacular names applied include aru (Sabah) and sempilau (Sabah) with various epithets. Major species include Casuarina equisetifolia; Gymnostoma nobile and G. sumatranum. The sapwood is lighter in colour and distinct from the heartwood, which is pink-brown, red-brown or dark brown.

Also known as Western Australian she-oak (Australia); Nakure (Fiji); Casuarina (India); Cemara, Cemara gunung, Cemara laut and Cemara Sumatra (Indonesia); Kabwi (Myanmar); Boi de fer de Riviera (New Caledonia); Casuarina (Pakistan); She oak (Papua New Guinea); Agoho (Philippines) Son and Son Tha Le (Thailand); and Dong-lieu and Phi lao (Vietnam).


DENSITY

The timber is very hard and very heavy with a density of 850-1,120 kg/m3 air dry.


NATURAL DURABILITY

The timber is moderately durable.


PRESERVATIVE TREATMENT

Its amenability to preservative treatment is average.


TEXTURE

Texture is coarse and uneven due to the presence of the extremely large aggregate rays. It has straight, spiral or wavy grain.


STRENGTH PROPERTIES

The timber falls into Strength Group B (Burgess, 1958) or SG 3 (MS 544:Part 2:2001).


MACHINING PROPERTIES

It is easy to resaw and cross-cut when green but is difficult when dry. Planing is also easy when green but difficult when dry and the planed surface is smooth to moderately smooth.


NAILING PROPERTY

Nailing property is rated as very poor.


AIR DRYING

The timber seasons fairly rapidly with moderate end-checking and staining, slight cupping, bowing and surface-checking as the main sources of degrade. 13 mm thick boards take approximately 2.5 months to air dry, while 38 mm thick boards take 4 months.


SHRINKAGE

Shrinkage is high, with radial shrinkage averaging 1.6% and tangential shrinkage averaging 3.4%.


USES

The timber is suitable for tool handles, fence posts and fuel both as firewood and charcoal.


REFERENCES

  1. 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.
  2. MS 544:Part 2:2001. Code of Practice for the Structural Use of Timber: Permissible Stress Design of Solid Timber.
  3. Wong, T. M. 1982. A Dictionary of Malaysian Timbers. Revised by Lim, S. C. & Chung, R. C. K. Malayan Forest Records No. 30. Forest Research Institute Malaysia, Kuala Lumpur. 201 pp.