DEFECTS IN TIMBER

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DEFECTS IN TIMBER A defect is a fault in the timber. Defects can occur in timber at various stages. • During the growing period of a tree • During felling of a tree • During conversion •... During seasoning period. Defects • Affect the quality of wood • Reduce the quantity of useful wood • Reduce the strength • Spoil the appearance. DEFECTS DUE TO ABNORMAL GROWTH. The following defects are commonly found in wood due to abnormal growth or rupture of tissues due to natural forces. 1. CHECKS Usually occur along the ends of timber. These are the separation of the wood fibres along the grain. It’s a longitudinal crack which is usually normal to the annual rings. A separation of the fibre along the grain forming a tissue which shows up on one face or at the end grains but does not continue through to the other side. These affect the durability of timber because they readily admit moisture and air. 2. SHAKES. These are longitudinal separations in the wood between the annual rings. These lengthwise separations reduce the allowable sheer strength. The separations make the wood undesirable when appearance is important. a. HEART SHAKE These are wide cracks or splits running through the heartwood of a tree. Occurs due to shrinkage of heartwood, when tree is overmatured. Cracks start from pith and run towards sapwood. [Show More]

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