Melunak


INTRODUCTION

The Standard Malaysian Name for the timber of Pentace spp. (Tiliaceae). Vernacular names applied include balong ayam (Peninsular Malaysia), baru (Sarawak), janda baik (Peninsular Malaysia), kebal ayam (Peninsular Malaysia), kempayang hantu (Peninsular Malaysia), melunak (Peninsular Malaysia) with various epithets, pinang baik (Peninsular Malaysia) and takalis (Sabah) with various epithets. Major species include P. adenophora, P. curtisii, P. laxiflora, P. macrophylla and P. triptera. The sapwood is yellow or light straw-coloured and is moderately sharply defined from the heartwood, which is brown with a red or pink tinge or red-brown.

Also known as Melunak (Brunei); Sisiet and Tassiet (Cambodia); Kayu pinang and Pinang (Indonesia); Mai si siat and Sisiet (Laos); Kashit, Thitka, Thit-kashit and Thitsho (Myanmar); Si-Sat, Sisiat, Sisiat-pluak and Tongsuk (Thailand); and Nghien (Vietnam).


DENSITY

The timber is a Light Hardwood with a density of 530-755 kg/m3 air dry.


NATURAL DURABILITY

Based on the standard graveyard test on melunak conducted at the Forest Research Institute Malaysia (FRIM), the average service life of the untreated specimens was 2.1 years. Melunak is therefore classified as moderately durable under exposed conditions. When the specimens were treated with creosote to an average absorption of 90 kg/m3 (5.6 lb/ft3) by the open tank method and tested, it was found that all the 40 test sticks were destroyed after 14.2 years, showing that treated melunak can be rendered durable by treatment.   


PRESERVATIVE TREATMENT

The timber is very difficult to treat with preservatives.


TEXTURE

Texture is moderately fine and even with shallowly to deeply interlocked grain.


STRENGTH PROPERTIES

The timber falls into Strength Group C (Engku, 1988b) or SG 5 (MS 544:Part 2:2001).


Strength Properties of Melunak (P. triptera)
 

Condition

Moisture Content(%)

Modulus of Rupture(MPa)

Modulus of Elasticity(MPa)

Impact bending(mm)

Compression parallel to grain (MPa)

Side hardness(Newton)

Shear parallel to grain (MPa)

Green

63

69

10,600

790

35.4

4,050

7.7

Air dry

16.1

85

12,000

710

43.6

4,090

10.8


MACHINING PROPERTIES

It is slightly difficult to difficult to resaw and is easy to slightly difficult to cross-cut. Planing is easy to slightly difficult and the quality of finish is generally smooth but the green material shows some grain pick-up in the radial direction.


Machining Properties of Melunak (P. triptera)  

Test Condition

Sawing

Planing

Boring

Turning

Re-sawing

Cross Cutting

Ease of planing

Quality of finish

Ease of boring

Quality of finish

Ease of turning

Quality of finish

Green

slightly difficult

easy

easy

tangential smooth; radial rough due to grain pick-up

-

-

-

-

Air dry

difficult

slightly difficult

slightly difficult

smooth

easy

smooth

easy

moderately smooth


NAILING PROPERTY

The nailing property is rated as good.


AIR DRYING

The timber seasons fairly slowly with very few defects. Slight bowing, twisting, end-checking and staining are the main sources of degrade. 13 mm thick boards take 3.5 months to air dry, while 38 mm thick boards take 5 months.


SHRINKAGE

Shrinkage is moderate, radial shrinkage averages 1.4% while tangential shrinkage averages 2.5%.


DEFECTS

Melunak logs are normally free from defects. The timber of P. triptera has been recorded to be very slightly attacked by powder-post beetles and shot-hole borers (Desch, 1954). Melunak timber is classified as rarely susceptible to powder-post beetles attacks (Menon, 1957). No sap-stain infection has been recorded.


USES

The timber is suitable for interior finishing, decorative works, panelling, mouldings, superior joinery, cabinet making, furniture, flooring, ornamental items, joists, railway sleepers, plywood, staircase (apron lining, carriages, riser, stringer, tread, bullnose, round end and winder), pallets (expendable and permanent light duty types) and other light construction. There is a suggestion that this timber will make good diving boards. In Burma, similar timber is sold under the name of 'Burma Mahogany' or 'Thitka' and is a very popular wood for high class furniture.


REFERENCES

  1. Desch, H. E. 1954. Manual of Malayan Timbers. Vol. II Mal. For. Rec. No. 15.
  2. Engku Abdul Rahman Chik. 1998b. Basic and Grade Stresses for Strength Groups of Malaysian Timbers. Malayan Forest Service Trade Leaflet No. 38. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 13 pp.
  3. Ho, K. S. 1983. Malaysian Timbers - Melunak. Malaysian Forest Service Trade Leaflet No. 80. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 6 pp. 
  4. Menon, K. D. 1957. Susceptibility of Commercial Species of Malaysian Timbers to Powder-post Beetle Attack. Mal. For. Vol. 20(1) pp.19-23.
  5. 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.
  6. MS 544:Part 2:2001. Code of Practice for the Structural Use of Timber: Permissible Stress Design of Solid Timber.
  7. 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.