ABSTRACT

Wood quality Wood has been an article of commerce for many centuries, some areas exporting exotic decorative woods and others supplying straight and strong structural woods. In the past high transportation costs were justified only for the most valuable woods and even normal construction wood imported, for example, into Great Britain in the 19th century was generally slow-grown and free from sapwood. Dwindling resources have since resulted in the introduction of thinning to encourage maximum yield, giving rapidly grown trees with wide rings, principally composed of spring wood. As the trees are felled when comparatively small in diameter a large proportion of the wood is now sapwood; Swedish redwood (Scots pine) supplied as sawnwood for building is now approximately 50% sapwood. Whilst the strength properties are not significantly affected by wide rings and the presence of a high proportion of sapwood, the wood is far less durable and far less stable than the slow-growing heartwood that was commonly used in the past.