Light Hardwoods - Nyatoh

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.

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).

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.

Nailing Property

Nailing property ranges from good to excellent.

Air drying

The seasoning properties of some species tested are summarised below:

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.

SHRINKAGE

The shrinkage of nyatoh is summarised below:

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

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.

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

MS 544:Part 2:2001. Code of Practice for the Structural Use of Timber: Permissible Stress Design of Solid Timber.

Thomas, A.V. 1950. Malayan Timbers -Jelutong, Nyatoh. Mal. For. Ser. Trade Leaflet No.13.

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.

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.