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How to identify timber quality

 

Each timber-producing region in the world has its own set of rules for grading their timber, depending on how the timber will be used.

 

United States

Most timbers (e.g. Oak, Ash, Maple, Cherry and Walnut) in the USA are used in furniture production. Boards are graded lower if they have knots, cracks, wane or are of shorter lengths. Grade is generally determined byhow many board feet can be recovered from the plank.

 

Malaysia

In Malaysia, structural timbers such as Balau, Keruing and Meranti are graded according to the presence of knots, warping, sapwood and shotholes.

 

South Africa

In South Africa, Pine is graded according to its MoE (Modulus of Elasticity) as it is used mainly in the construction industry.

 

West Africa

In West Africa, tropical timbers are only graded as “export” or “local”. With rapid economic growth in Ghana, Cameroon, the Congos and Gabon, there is a steep increase in local demand for timber. This has led to less timber being available for export, and grades have declined.

More importantly for export-quality timber, traditional harvesting areas in the north have been heavily logged over the years. The result is that logs available for sawmilling in these areas tend to be smaller and from younger trees. All the big logs have long gone.

Contrary to this, infrastructure in the Congo basin is under-developed at best, so much less logging has taken place here. Regulation and controls have been stepped up across the region in recent years. In the Congo basin there are still plenty of big, old trees and harvesting is done under a strict rotation regime. In the IHC concession, harvesting rotates on a 30-year cycle so medium-sized trees are allowed to grow to full maturity before being harvested.

Where smaller trees are harvested, the timber is less dense, more sapwood is prevalent and tension in the wood is highly likely. It is not always easy to grade against these defects as they only come to the fore once the timber is machined.