Perupok


INTRODUCTION

The Standard Malaysian Name for the timber of Lophopetalum spp. (Celastraceae). Vernacular names applied include dual (Sabah), kerueh (Peninsular Malaysia) and tinjau tasek (Pahang). Major species include L. floribundum, L. javanicum, L. multinervium, L. pallidum, L. subobovatum and L. wightianum. The sapwood is not clearly defined and is generally lighter in colour than the heartwood, which is light yellow or light yellow-brown when dry and pink when freshly cut.

Also known as Perupok (Brunei); Banati and Narikeli (India); Medang kerupuk, Pasana and Perupuk (Indonesia); Mondaing, Tuang-yemane and Yemane-apyu (Myanmar); Abuab (Philippines); Dimi, Phuamphrao, Samet-thung, Seng Sa Lung and Song Sa Lum (Thailand); and Sang trang (Vietnam).


DENSITY

The timber is a Light Hardwood with a density of 480-640 kg/m3 air dry.


NATURAL DURABILITY

The natural durability of perupok was investigated as far back as 1930, when Foxworthy and Woolley reported that a consignment of 25 pieces of an unidentified Lophopetalum was buried in a standard graveyard test (Foxworthy et Woolley, 1930). All the specimens were destroyed in one year, thus showing that perupok is non-durable. A more recent test was conducted on L. floribundum. Dahlan and Tam (in press), reported that 40 pieces of the timber were buried in the Kepong test sites. Three pieces were destroyed within the first 6 months, while the last specimen was destroyed in 2.5 years. The average life-span was calculated to be 1.9 years, thus confirming that perupok is naturally non-durable.

Treated perupok, however showed a vast improvement in its durability. A batch of 40 sticks of L. floribundum was treated with 100% creosote to an average absorption of 390 kg/m3 (24.3 lb/ft3) and then buried in the Kepong test sites. After more than 12 years, all 40 pieces are sound with no signs of any deterioration (Tam, 1983). This shows that perupok, when treated with the appropriate preservatives can be rendered extremely durable.   


PRESERVATIVE TREATMENT

The timber is classified as difficult to treat with preservatives. 

    
TEXTURE

Texture is fine to moderately fine and even, with interlocked grain.


STRENGTH PROPERTIES

The timber falls into Strength Group B (Engku, 1988b) or SG4 (MS 544:Part 2:2001).


Strength Properties of Perupok

Species

Test Condition

Modulus of Elasticity(MPa)

Modulus of Rupture(MPa)

Compression parallel to  grain (MPa)

Compression perpendicular to grain (MPa)

Shear Strength (MPa)

L. floribundum

Green

11,300

62

32.3

3.4

7.7

Air dry

12,600

79

34.5

5.6

9.0

L. subovatum

Green

11,700

64

32.8

3.4

7.2

Air dry

12,200

76

42.8

5.3

7.4


MACHINING PROPERTIES

It is easy to saw and works very well and the planed surface produced is smooth.


Machining Properties of Perupok 
 

Species

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

L. floribundum

Green

easy

easy

easy

smooth

easy

smooth

-

-

Air dry

easy

easy

easy

smooth

easy

smooth

easy

smooth

L. subovatum

Green

easy

easy

easy

smooth

easy

smooth

-

-

Air dry

easy

easy

easy

smooth

easy

smooth

easy

smooth


NAILING PROPERTY

The nailing property is poor.


AIR DRYING

The timber seasons very rapidly but is prone to end-checking, splitting, surface-checking and some insect attacks during seasoning. 13 mm thick boards take 1 month to air dry, while 38 mm thick boards take 1.5 months.


SHRINKAGE

Shrinkage is fairly high, especially in the radial direction. Radial shrinkage averages 2.4% while tangential shrinkage averages 3%.


DEFECTS

The logs of perupok are very free from defects, apart from some attacks by staining fungi. 


USES

The timber is suitable for interior finishing, panelling, mouldings, partitioning, furniture, flooring, staircase (apron lining, handrail and sprandrel framing), joinery, cabinet making, ornamental items, plywood, packing boxes and crates, railway sleepers, posts, beams, joists and rafters. 


REFERENCES

  1. Dahlan b. Jantan & Tam, M.K. Natural Durability of Some Malaysian Timbers by Stake Tests. (in press)
  2. Engku Abdul Rahman Chik. 1988b. Basic And Grade Stresses For Some Malaysian Timbers. Malayan Forest Service Trade Leaflet No. 38. The Malaysian Timber Industry Board And Forest Research Institute Malaysia, Kuala Lumpur. 13 pp.
  3. Foxworthy, F. W & Woolley, H. W. 1930. Durability of Malayan Timbers. Mal. For. Rec. No.6.
  4. 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 Insitute Malaysia, Kuala Lumpur. 48 pp.
  5. MS 544: Part 2: 2001: Code Of Practice For Structural Use Of Timber. Permissible Stress Design of Solid Timber.
  6. Tam, M. K. 1983. Unpublished report
  7. Wong, T. M. 1982. A Dictionary of Malaysian Timbers. Revised by Lim, S. C. & Chung, R. C. K. Malayan Forest Record No. 30. Forest Research Institute Malaysia Kuala Lumpur. 201 pp.
  8. Wong, T. M. 1983. Malaysian Timbers - Perupok. Malaysian Forest Service Trade Leaflet No. 76. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 8 pp.