Bitis


INTRODUCTION

The Standard Malaysian Name for the timbers of Madhuca utilis, Palaquium ridleyi and P. stellatum (Sapotaceae). Bitis is essentially a Peninsular Malaysian name and in Sabah and Sarawak, the timber is not differentiated from the lighter species and they are sold together as nyatoh. Other vernacular names recorded include belian (Peninsular Malaysia) and seminai (Peninsular Malaysia). The sapwood is yellow-brown to purple-grey-brown and is sharply defined from the heartwood, which is red-brown to purple- or chocolate-red-brown.

Also known as Bitis and Nyatoh (Brunei); Mahua, Nyatoh,Nyatuh Abang, Seminai and Sulewe (Indonesia); Meze kamzaw (Myanmar), Kajoe torong (Papua New Guinea); Betis and Maloba (Philippines); and Chik-nom, Khanun-nok, Ma Sang and Ma Sarng (Thailand).


DENSITY

The timber is a Heavy Hardwood with a density of 820-1,200 kg/m3 air dry.


NATURAL DURABILITY

The standard graveyard tests conducted at the Forest Research Institute Malaysia (FRIM) have shown that the average service life of M. utilis is 5.5 years under the external exposed conditions and thus, it is classified as durable according to the Malaysian classification (Mohd Dahlan et al 1987). 


PRESERVATIVE TREATMENT

The timber is very difficult to treat with preservatives.


TEXTURE

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


STRENGTH PROPERTIES

The timber falls into Strength Group A (Engku, 1988b) or SG 1 (MS 544:Part 2:2001).


Strength Properties of Bitis (M. utilis)

Test Condition

Modulus of Elasticity (MPa)

Modulus of Rupture (MPa)

Compression parallel to grain (MPa)

Compression perpendicular to grain (MPa)

Shear Strength (MPa)

Green

21,900

123

73.6

12.21

11.3

Air dry

23,800

171

90.3

12.48

15.4


MACHINING PROPERTIES

It is slightly difficult to difficult to resaw, easy to slightly difficult to cross-cut. Planing is slightly difficult but the planed surface is smooth.


Sawing and Woodworking Properties of Bitis (M. utilis

 Condition of test

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

slightly difficult

smooth

slightly difficult

slightly rough, tendency to split

-

-

Air dry

difficult

slightly difficult

slightly difficult

smooth

slightly difficult

slightly rough

difficult

rough


NAILING PROPERTY

Nailing property is rated as poor.


AIR DRYING

The timber seasons slowly with moderate end-checking, splitting and surface-checking as the major sources of defects. 38 mm thick boards take approximately 6 months to air dry.


KILN-DRYING

The kiln-drying properties of bitis have not been evaluated. However, based on the physical properties as well as the air drying properties of the timber, it is envisaged that the timber is fairly difficult to dry. A mild schedule (e.g. Schedule B) should therefore be used.


Kiln Schedule B

Moisture Content
(%)

Temperature
(Dry Bulb)

Temperature
(Wet Bulb)

Relative Humidity (%) (approx.)

F

C

F

C

Green

105

40.5

101

38.0

85

40

105

40.5

99

37.0

80

30

110

43.5

102

39.0

75

25

115

46.0

105

40.5

70

20

130

54.5

115

46.0

60

15

140

60.0

118

47.5

50


SHRINKAGE

Shrinkage is high. Radial shrinkage averages 2.8% while tangential shrinkage averages 4%.


USES

The timber is suitable for all forms of heavy construction, bridges, marine construction, piling, posts, beams, joists, rafters, railway sleepers, flooring (heavy traffic), fender supports, poles, mallets, tool handles (impact), laboratory benches, heavy duty furniture, columns (heavy duty), door and window frames and sills, staircase (newels, risers, treads, bullnoses, round ends and winders), vehicle bodies (framework and floor boards), telegraphic and power transmission posts and cross arms.


REFERENCES

  1. Engku Abdul Rahman Chik. 1988b. 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.  
  2. Grewal, G.S. 1979b. Kiln-drying Characteristics of Some Malaysian Timbers. Timber Trade Leaflet No. 42. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 20 pp.  
  3. Lim, S.C. 1989. Malaysian Timbers - Bitis. Timber Trade Leaflet No. 110. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 6 pp.
  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 Institute Malaysia, Kuala Lumpur. 48 pp.
  5. Mohd Dahlan Jantan & Tam Mun Kwong (1987) - Natural Durability of Malaysian Timbers. Timber Trade Leaflet No. 28. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur.
  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.