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Defects of timber
Short answer
Timber defects include knots, shakes, warping, checks, splits, honeycombing, and decay from fungi or insects. They arise from natural growth, improper seasoning, conversion faults, and biological attack, reducing strength and durability.
What are the defects of timber?
Defects reduce the strength, durability and appearance of timber. They are grouped by cause.
1. Defects due to natural forces (during growth)
- Knots: bases of branches buried in the trunk; they weaken timber and distort grain.
- Shakes: cracks that separate fibres along the grain: heart shake, star shake, cup shake (ring shake), and radial shake.
- Wind cracks and upsets, rind galls, burls, twisted fibres, and water stain.
2. Defects due to seasoning
- Warping (bow, cup, twist, spring), checks, splits, honeycombing, case hardening, collapse.
3. Defects due to conversion
- Chip marks, torn grain, diagonal grain, wane (rounded edge with bark).
4. Defects due to fungi and insects
- Dry rot, wet rot, blue stain, and attack by termites, powder-post beetles and marine borers.
Note: Wood with such defects is graded lower or rejected.
✓ Answer checked by Claude Opus 5.5 (high effort)
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