Seasoning defects

Some of the commonest defects in timber are associated with the effects of seasoning. During the seasoning process, the contraction of the timber is different in the three major directions; furthermore, as described in the 'Moisture movement' section above, the outside of the timber tends to dry out more rapidly than the interior. These combined effects cause distortion of the timber including warping and the risk of rupture of the timber to produce surface checks and splits (Fig. 4.13).

Shakes

Major splits within timber are termed shakes, and these may result from the release of internal stresses within the living tree on felling and seasoning; however, some fissures may be present within the growing timber. Commonly, shakes are radial from the exterior of the trunk, but star shakes which originate at the centre or pith may be associated with incipient decay. Ring shakes follow round a particular growth ring and are frequently caused by the freezing of the sap in severe winters.

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