Nyatoh


INTRODUCTION

The Standard Malaysian Name for the light and reddish timber of the family Sapotaceae. Vernacular names applied include nyatoh (Peninsular Malaysia, Sabah and Sarawak) with various epithets and also bengku (Peninsular Malaysia), ekor (Peninsular Malaysia), jangkar (Sarawak), mentua taban (Peninsular Malaysia), rian (Sarawak), semaram (Peninsular Malaysia), sundik (Peninsular Malaysia), taban (Peninsular Malaysia) and taban merah (Peninsular Malaysia). Major species of the timber include Madhuca curtisii, M. kingiana, M. motleyana, M. erythrophylla, M. laurifolia, M. longistyla, M. penicillata, M. sericea, M. sp. A, M. sp. B; Palaquium clarkeanum, P. gutta, P. hexandrum, P. hispidum, P. impressinervium, P. maingayi, P. microphyllum, P. obovatum, P. oxleyanum, P. regina-montium, P. rostratum, P. semaram, P. xanthochymum; Payena dasyphylla, P. lanceolata, P. maingayi and P. obscura. The sapwood is lighter in colour and is only moderately sharply differentiated from the heartwood, which is deep pink-red or red-brown.

Also known as Nyatoh (Brunei); Chorni (Cambodia); Bauvudi (Fiji); Mahua, Pali and Tali (India); Chonte, Nyatoh and Nyatuh (Indonesia); Jambadung (Laos); Kanzwe (Myanmar); Pencil cedar (Papua New Guinea); Alakaak, Kalipaya, Long-leafed nato, Malak-malak, Maniknik, Mindanao nato, Nato, Palak-palak, Red nato, Tagatoi and Tipurus (Philippines); Kirihembiliya and Tawenna (Sri Lanka); and Chik Nom, Chik-khao, Phikun-nok, Phikun-pa, Phikun-thuan and Tabun Dam (Thailand).


DENSITY

The timber is a Light Hardwood with a density of 400-1,075 kg/m3 air dry.


NATURAL DURABILITY

Nyatoh shows variable natural durability in accordance to the species. The majority of the species would fall into the moderately durable class but there are species that are non-durable as well as those which are durable. Results obtained from the graveyard tests conducted at the Forest Research Institute Malaysia (FRIM) on nyatoh species are given in the table below. The timber is subject to termite attacks and is also susceptible to fungal attacks. However, it is rarely susceptible to powder-post beetle attacks.

When treated with appropriate preservatives, nyatoh shows great durability. A series of tests using P. maingayi, treated with 100% creosote to an average absorption of 285 kg/m3 (17.82 lb/ft3) was started in 1949. The first stick was destroyed only after 12 years and after 32 years, seven sticks were still sound. Further tests involving other species of nyatoh also showed that this timber is very durable when treated. A series of test using P. gutta was started in 1966 and after 15 years, only three out of the original 40 test sticks were destroyed. A similar series, using P. impressinervium was started in 1969 and all the sticks were found to be still sound in 1981. However, in a duplicate trial, six out of an original 16 sticks were destroyed after 10.5 years. Diploknema sebifera, however gave a less impressive performance when tested. A series was started in 1971 and after 10 years, only six of the original 40 test sticks were still sound. 


Natural Durability of Nyatoh

Species

Average life span (years)

Durability classification

Diploknema sebifera

2.5

Moderately durable

Palaquium gutta

1.7

Not durable

P. impressinervium

5.5

Durable

P. maingayi

2.8

Moderately durable


PRESERVATIVE TREATMENT

The timber is classified as very difficult to treat with preservatives.  


TEXTURE

Texture is moderately fine to slightly coarse, with straight to shallowly interlocked and sometimes wavy grain.


STRENGTH PROPERTIES

Most species of nyatoh falls into Strength Groups B and C (Burgess, 1958). However, P. impressinervium falls into Strength Group A (Burgess, 1958). Nyatoh is also classified under SG 5 (MS 544:Part 2:2001).


Strength Properties of Nyatoh
 

Species

Test Condition

Modulus of Elasticity(MPa)

Modulus of Rupture(MPa)

Compression parallel to grain (MPa)

Compression perpendicular to grain (MPa)

Shear strength(MPa)

Ganua
motleyana

Green

9,800

50

24.8

-

-

Air dry

-

-

-

-

-

Palaquium gutta

Green

11,300

64

34.3

-

9.2

Air dry

12,200

79

44.5

-

11.0

P. hispidum

Green

10,600

60

29.9

3.17

7.6

Air dry

-

-

-

-

-

P. impressinervium

Green

17,000

97

53.7

6.07

11.7

Air dry

18,300

129

64.7

9.17

11.9

P. maingayi

Green

11,700

63

33.7

4.21

8.1

Air dry

-

-

43.5

4.48

11.0


MACHINING PROPERTIES

Wood working properties of the timber vary with most of the lighter species being easy to saw and work, producing surfaces that are smooth or rarely rough in the radial direction as in P. maingayi. The heavier species, like P. impressinervium, are very difficult to saw, cross-cut and work while the planed surface is only moderately smooth.


Machining Properties of Nyatoh 

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

Ganua motleyana

Green

easy

easy

easy

smooth

easy

smooth

-

-

Air dry

easy

easy

easy

smooth

easy

smooth

easy

smooth

Palaquium gutta

Green

easy to slightly difficult

easy

easy

smooth

easy

smooth

-

-

Air dry

slightly difficult

easy

easy

smooth

easy

smooth

easy

smooth

P. hispidum

Green

easy

easy

easy

smooth

easy

smooth

-

-

Air dry

easy

easy

easy

smooth

easy

smooth

easy

smooth

P. impressinervium

Green

very difficult

very difficult

easy

moderately smooth

difficult

moderately smooth

-

-

Air dry

very difficult

very difficult

slightly difficult

moderately smooth

difficult

moderately smooth

difficult

rough

P. maingayi

Green

easy

easy

easy

Tangential: smooth Radial: rough, due to grain pick-up

easy

smooth

-

-

Air dry

easy

easy

easy

smooth

easy

smooth

easy

smooth


NAILING PROPERTY

Nailing property ranges from good to excellent.


AIR DRYING

The seasoning properties of some species of nyatoh are summarised below:

Species

Time to air dry (months)

Remarks

13 mm thick boards

38 mm thick boards

Madhuca motleyana

3

4

Fairly slow drying; slight cupping.

Palaquium gutta

2

4

Fairly fast drying; slight cupping, bowing and splitting and insect attack; moderate end-checking.

P. hispidum

3.5

4.5

Fairly slow drying; slight bowing, end-checking and insect attacks.

P. impressinervium

4

6

Slow drying; slight end-checking and insect attacks.

P. maingayi

3

5

Fairly slow drying; slight bowing, end-checking and moderate insect attacks.


KILN-DRYING

Kiln Schedule E is recommended for the lighter species of nyatoh and 25 mm thick boards take approximately 11 days to kiln-dry. Heavier species should be kiln-dried using Schedule D or C. 


Kiln Schedule C

Moisture Content (%)

Temperature
(Dry Bulb)

Temperature
(Wet Bulb)

Relative Humidity (%)

F

C

F

C

Green

105

40.5

101

38.0

85

60

105

40.5

99

37.0

80

40

110

43.5

102

39.0

75

35

110

43.5

100

38.0

70

30

115

46.0

103

39.5

65

25

125

51.5

109

43.0

60

20

140

60.0

118

47.5

50

15

150

65.5

121

49.0

40

 

Kiln Schedule D

 Moisture Content (%)

Temperature (Dry Bulb)

Temperature (Wet Bulb)

Relative Humidity (%) (approx.)

F

C

F

C

Green

105

40.5

101

38.0

85

60

105

40.5

99

37.0

80

40

105

40.5

96

35.5

70

35

110

43.5

97

36.0

60

30

115

46.0

97

36.0

50

25

125

51.5

101

38.0

40

20

140

60.0

105

40.5

30

15

150

65.5

112

44.5

30

 

Kiln Schedule E

Moisture Content (%)

Temperature (Dry Bulb)

Temperature (Wet Bulb)

Relative Humidity (%)(approx.)

F

C

F

C

Green

120

48.5

115

46.0

85

60

120

48.5

113

45.0

80

40

125

51.5

116

46.5

75

30

130

54.5

117

47.0

65

25

140

60.0

120

48.5

55

20

155

68.0

127

53.0

45

10

170

76.5

136

58.0

40


SHRINKAGE

The shrinkage of nyatoh is summarised below:

Species

Shrinkage (%)
(Green to air dry)

Remarks

Radial

Tangential

Madhuca motleyana

2.4

3

Fairly high shrinkage

Palaquium gutta

1

1.9

Fairly low shrinkage

P. hispidum

1.3

2.8

Fairly high shrinkage

P. impressinervium

3

3.6

High shrinkage

P. maingayi

2.3

4.3

Very high shrinkage



DEFECTS

Generally, nyatoh logs are rather free from defects. Spongy heart has been observed in a few logs. Other defects such as defective cores, gum pockets and areas of rot have been noted in test material of P. impressinervium. Borer holes, probably caused by longicorn beetles have been recorded (Thomas, 1950). The logs have a tendency to split at the ends if care is not taken to have them stored properly. End-coating of the logs is recommended if they are to be stored for any period prior to conversion.  


USES

Nyatoh is a very popular timber for furniture and solid door. It is suitable for high class decorative works and interior finishing such as panelling, mouldings and partitioning. Other uses include joinery, flooring, decking, staircase (angle block, rough bracket, baluster, balustrade, carriage, handrail, riser, stringer, tread, bullnose, round end and winder), columns (light duty), plywood, pallets, beams, rafters, joists (light duty), door and window frames and sills (internal use only), vehicle bodies (planking), ship and boat building (keels, keelsons, framework and general planking), railway sleepers and tool handles (impact).


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. Thomas, A. V. 1950. Malayan Timbers - Jelutong, Nyatoh. Mal. For. Ser. Trade Leaflet No. 13.
  5. Wong, T. M. 1981. Malaysian Timbers - Nyatoh. Malaysian Forest Service Trade Leaflet No. 54. The Malaysian Timber Industry Board and Forest Research Institute Malaysia, Kuala Lumpur. 12 pp.
  6. 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.