Wednesday 3 September 2008

Notes: Term 1, Week 1 - Natural woods



Hardwoods:
Hardwoods are generally deciduous broad-leaved species. Some examples of hardwoods would be:
Oak, Ash, Walnut, Yew, Beech, Teak

Softwoods:
Softwoods are generally evergreen. Some examples of softwoods would be:
Scots pine, Spruce, Douglas fir

Problems with using wood:
Woods is a natural material and so can have many defects. It is not consistent in structure. A common problem found in wood is knots. These found where branches have started to grow out of the trunk. Knots can weaken the structure as well as produce and irregular grain.

Conversion:
Conversion is the term used when sawing a tree trunk into usable pieces of timber. The choice of conversion method can enhance the grain and help make the materials more stable.
Different methods of sawing:
There are 2 main ways timber is cut into planks. Plain sawing and quarter sawing.












When the wood is plain sawn the planks produced are of a lower quality but more planks are produced as you are maximising the amount of wood you are getting from the trunk. When the wood is quarter sawn a higher quality of plank is produced but less planks can be produced.

Seasoning woods:
Seasoning is the controlled drying of timber. This can be achieved by natural seasoning or kiln drying. For both methods the moisture content must be lower than 20%. The ideal moisture content for a piece of wood is when the wood has the same moisture content as the air surrounding it.
For every 25mm of plank that you want to naturally season you will have to leave the wood for 1 year.





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