Defects in wood

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Knots
Knots occur where branches have begun to grown out of the trunk of a tree. This can weaken the structure of the material and cause an irregular grain.
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Splits
Separations of fibre along the grain; which occur when the material is drying or through natural events such as lightening strikes which cause hairline fractures.
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Shrinkage
When the material is being dried out and it loses moisture. If a wood is dried to a higher moisture content than its use then it will quickly show shrinkage. Warping, bowing, twisting and cupping are examples of shrinkage.
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Dry rot
The result of a fungus which reduces the timber to a dry, powdery consistency leaving the material with little strength.
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Wet rot
Occurs where conditions fluctuate between wet and dry. The alternating conditions break the wood down by decomposing it.
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Insect attack
As the insects attack and lay their eggs, the larvae burrow down through the wood and damage it.
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Seasoning
The controlled drying of woods; ideally to the same moisture content as the surrounding conditions (the Equilibrium Moisture Content). Seasoning increases strength, reduces the risk of corrosion when in contact with metals and reduced risk of decay.
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Conversion
Sawing a tree trunk into useable pieces of timber. Methods include slab sawing and quarter sawing. As well as cutting the timber into a more useable shape, conversion can enhance the grain and make the material more stable.
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Other cards in this set

Card 2

Front

Separations of fibre along the grain; which occur when the material is drying or through natural events such as lightening strikes which cause hairline fractures.

Back

Splits

Card 3

Front

When the material is being dried out and it loses moisture. If a wood is dried to a higher moisture content than its use then it will quickly show shrinkage. Warping, bowing, twisting and cupping are examples of shrinkage.

Back

Preview of the back of card 3

Card 4

Front

The result of a fungus which reduces the timber to a dry, powdery consistency leaving the material with little strength.

Back

Preview of the back of card 4

Card 5

Front

Occurs where conditions fluctuate between wet and dry. The alternating conditions break the wood down by decomposing it.

Back

Preview of the back of card 5
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