Jongkong

INTRODUCTION

The Standard Malaysian Name for the timber of Dactylocladus stenostachys (Crypteroniaceae). Vernacular names applied include gatal (Sarawak), medang jongkong (Sarawak), medang tabak (Sabah), merebong (Sarawak) and tanjiong awam (Sabah). This is a monotypic timber which is absent in Peninsular Malaysia. The sapwood is not differentiated from the heartwood, which is light brown when fresh and darkens to pink-brown or red-brown.

Also known as Medang tabak (Brunei); and Mentibu, Merebung, Pardu, Sampinur and Turit (Indonesia).


DENSITY

The timber is moderately hard and moderately heavy with a density of 495-610 kg/m3 air dry.


NATURAL DURABILITY

The timber is reported to be non-durable.


TEXTURE

Texture is fine and even, with straight or slightly interlocked grain.


STRENGTH PROPERTIES

The timber falls into Strength Group D (Burgess, 1958) or SG 6 (MS 544: Part 2:2001).


MACHINING PROPERTIES

It is reputed to work very well and produces a smooth and lustrous surface.


NAILING PROPERTY

Nailing property is rated as poor.


AIR DRYING

The timber seasons fairly slowly with moderate amount of bowing and end-checking and a slight amount of cupping and splitting as the main sources of degrade. 13 mm thick boards take 3 months to air dry, while 38 mm thick boards take 5 months.


SHRINKAGE

Shrinkage is variously reported to be fairly high to very high. The data obtained by the Forest Research Institute Malaysia (FRIM) showed that radial shrinkage is 1.1% while tangential shrinkage is 1.8%. Work done in Sarawak showed that this timber has very high shrinkage with radial shrinkage averaging 3.1% and tangential shrinkage averaging 5.5%.


USES

The timber is suitable for concrete shuttering, flooring, partitioning, furniture and possibly for plywood manufacture.


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. 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 Institute Malaysia, Kuala Lumpur. 48 pp.
  3. MS 544:Part 2:2001. Code of Practice for the Structural Use of Timber: Permissible Stress Design of Solid Timber.
  4. 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.