Balau
Balau is a hardwood that originated from Malaysia but used commonly all over the world. It is in the last 20 years that it has become synonymous with hardwood construction in South Africa. Because of its density and durability it has become the premier choice for external and marine applications.
Discription
The heartwood is light brown to yellowish light brown gradually turning dark brown. The sapwood is lighter in colour than the heartwood. As the timber weathers it turns a silvery grey. The grain ranges from straight to spiralled and interlocked. The texture varies from fine to coarse and in general it is slightly coarse to coarse. Resin pockets do occur.
Surface checking is common with Balau as it is a “wet” timber, (because of its density it dries over a very long period of time and therefore cannot be accelerated with kiln drying) this is however common to all hardwoods in this category.
The tree is commonly attacked by Pinhole Borer Beetle which leaves the timber with small and scattered pattern of small holes. Referred to as “Pin Hole” this attack occurs only in the tree form or when the log is freshly felled it is a characteristic of Balau and it does not affect the strength of the timber in any way.
Knots can be present but they are usually sound. The timber is naturally very durable and does not accept treatment well. Acidic reactions occur when timber is in contact with ferrous metals, this is seen as black “ink like” markings, and these fade in time.
Leaching may occur during the first wet season after installation but this gradually reduces after several seasons. Nailing is difficult to impossible, and pre boring is essential when using screws. Workability with hand tools is difficult but it machines well. The use of stainless steel screws is advised. Shrinkage occurs so tolerance must be allowed for.
Uses
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All form of heavy construction
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Marine Construction
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Ship building (keels, keelsons, framework)
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Piling
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Wharves and jetties
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Heavy duty beams and columns
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Bridge construction
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Railway sleepers
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Vehicle bodies
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Boat building
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Fenders
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Heavy duty pallets
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Telegraph posts and cross arms
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Posts
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Joists
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Rafters
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Decking and outdoor furniture
NB: It is advised to use this timber in external applications only as it has a tendency to move in service, the use of traditional carpentry methods as well as mechanical fixing is recommended
Properties
Density
Shrinkage Radial
Shrinkage Tangentail
Modulus of rupture
Modulas of elastisity
Compresstion parallel to grain
Compression perpendiccular to grain
Shear parallel to grain
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1000 kg/m3
1.7 - 2.1%
3.5 - 3.9%
142 N/mm2
20100 n/mm2
76.00 N/mm2 (Maximum crushing strengh)
9.79 N/mm2
15.00 N/mm2 (Maximum shearing strengh)