CONTRIBUTORS- WOOD WORKS
The global teak resource is therefore likely to expand, provided that appropriate cultural treatments, effective protection and management systems are applied to both the natural teak forests and the plantations on a long term sustainable basis.
Teak wood is dark golden yellow, turning dark brown upon prolonged exposure to air. Irregular figuring of darker streaks or marks, is quite common. The wood has a distinct leathery smell, but no appreciable taste. It is not lustrous. When first cut, the wood has an oily to sticky feel to it. Teak is used in shipbuilding( decking and interiors), exterior joinery, decking, veneer and plywood for panelling in homes and offices. It is in demand as a furniture wood. It is resistant to chemicals and is used for products exposed to acids. It is also used for boxes, chests, carvings and wood turning.
THE PROPERTIES OF THIS OUTSTANDING TIMBER ARE SUMMARISED BELOW FOR THE WOOD ENTHUSIAST:
TEAK: HARD FACTS
Botanical / scientific name:
Tectona grandis L. f. Family: Lamiaceae – the Mint family
Trade name:
Teak Other names: Burmese, Indian, Rangoon, Moulmein and Java teak; Kyun( Myanmar), Giati( Vietnam);
Origin: Myanmar, India, Peninsular Malaysia, Cambodia, Laos, Thailand and Java.
Conservation status:
Bole characteristics:
Teak is not CITES-listed and its conservation status has not been evaluated.
Tree size is variable, affected by site, soil and climate. The tree usually grows to 39 to 45m in height with a diameter of 1.2 to 1.5m. Trees in Myanmar can reach diameters of 1.8 to 2.4m.
May sak( Laos); Djati, Jati( The Netherlands); Teck( France); Teca( Spain)
It is grown in commercial plantations in many countries, mainly tropical Africa and tropical America.
However, it is increasingly rare in its natural range, due to exploitation.
The length of the clean bole can vary from 6m to 27m. Trees that produce saw timber of these dimensions are usually 70 to 90 years old.
Colour:
Grain pattern:
Density( at 12 % moisture content):
Strength / bending properties:
Seasoning:
Durability and preservative treatment:
Working and finishing properties:
The heartwood is dark golden yellow, often with darker markings, turning dark brown to black on exposure.
Straight to an occasional wavy grain, displaying mottled figuring.
Timber from natural stands: Average 673kg / m 3( Ref 1) 480( 600-719) 839( Ref 2) 630( 650-680) 750kg / m 3( Ref 3) 560-800kg / m 3( Ref 4)
Teak has excellent strength properties, making the timber suitable for a wide range of structural uses. It has medium to high crushing strength, low to medium bending strength( MOR – Modulus of Rupture), very low to low bending stiffness( MOE – Modulus of Elasticity), very low to low toughness,
The wood seasons well, but rather slowly with very little shrinkage.
Teak heartwood has outstanding natural durability, a feature which has long been appreciated in the shipbuilding industry. It contains an oil that makes the wood very resistant( but not immune) to termite and marine borer attack.
The wood works very well, but is hard on tools. Very sharp cutting edges are essential during processing. Morticing and drilling operations can be done cleanly.
The narrow white to greyish sapwood is clearly demarcated from the heartwood and approximately 30mm wide.
The texture is moderately coarse to coarse and uneven.
Timber from plantations: 720-730kg / m 3 – 13 to 15 year old plantation trees in Costa Rica( Ref 3)
its Janka side grain hardness classification is‘ soft’ and its shear parallel to the grain classification is‘ low to medium’.
Both air- and kiln-drying can be done with no or very slight drying defects and once dry, the timber is remarkably stable in use.
It is resistant to fungal attack. The sapwood is susceptible to infestation by powder-post beetle. The heartwood is extremely resistant and the sapwood moderately resistant to preservative treatment.
The wood has good nailing and screwing properties and varnishes, stains and polishes well. Gluing results are best on freshly machined or sawn surfaces as the oily nature of aged surfaces may present problems in bonding.
// FEB / MARCH 2017 63