Bruising
Also called: denting, crushing
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Bruising is damage done to wood not by cutting it but by crushing it: a dent or a patch of crushed fibre left where something pressed too hard against the surface.
Where bruising happens
Clamps and the blocks that spread their pressure are a common cause. Shaped pine pads fit between a moulded rail and the clamping chocks, the shaped blocks a clamp bears against, so the chocks themselves do not bruise the rail. Those pads may carry wire points that bite into the chock's face to stop it slipping, since a clamp with no supporting block or nail underneath it is prone to slipping out of place. Tightening wedges or bolts too far can crush the backing timbers beneath them and weaken the joint. Fitted parts bruise too: out-of-line or angled dowel holes are put right by gluing a peg into the old hole and reboring it true, because a bent or crushed peg badly weakens the joint. A door's capping, the moulded strip covering the top of a rebated joint, is kept clear of it by a small gap so it does not bruise the joint each time the door opens. Cutting tools can bruise as well as cut: a blade with a thin, sharp edge lets a woodworker pare between dovetails without denting the neighbouring wood surfaces. Planing can bruise at a microscopic scale, too. A defect called grain raise happens when the plane crushes the earlywood cells, the softer, larger cells laid down early in each growth ring, at the wood's surface.
Repairing it
Bad bruising and deep dents are repaired by cutting them out and filling with wood or a hard stopper such as plastic wood, a wood-coloured filler paste.