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Iroko
Desription
When freshly cut, or when unexposed to light, the heartwood is a distinct yellow colour, but on exposure to light it quickly becomes golden-brown. The sapwood is narrow, being about 50mm to 75mm wide, and clearly defined. The grain is usually interlocked and the texture is rather coarse but even, and the wood weighs on average 660 kg/m3 when dried. Large, hard deposits of calcium carbonate called ‘stone’ deposits, are sometimes present in cavities, probably as a result of injury to the tree. They are often enclosed by the wood and not visible until the time of sawing, though the wood around them may be darker in colour, thus giving an indication of their presence.
Features
Use
Cladding, Decking, Exterior and interior joinery
Colour
Dark yellow/brown
Durability
Durable
Density in kg/m3
660
The European Ash
The Tree
A tall, graceful tree, reaching a height of 30m to 42m on good sites, with a clear bole averaging 9m in length, and occasionally more. The diameter varies from 0.5m to 1.5m.
The Timber
There is usually no distinction in colour between sapwood and heartwood, freshly cut wood being whitish to pale brown with a pink cast, turning to a slightly brownish-white after drying. In some logs, an irregular dark brown or black heartwood is found, but this is not necessarily a defect, as the timber is normally quite sound. Logs containing dark heart streaks are often enhanced in value because of the decorative nature of the wood which is known as olive ash.
Drying
Dries at a fairly rapid rate without excessive surface checking and splitting, but under the influence of severe temperatures, there is a tendency to distort and for end splitting to occur. Distorted stock responds well to reconditioning kiln treatment.
Strength
Similar to oak in general strength properties, but tougher and more resistant to splitting.
Working Qualities
Good – Although tough, ash works and machines quite well, and finishes to a reasonably smooth finish. It can be glued, stained, and polished.
The European ash tree (Fraxinus excelsior) is native to Europe, the British Isles, North Africa, and Western Asia.
