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WEEK FIVE (5)
TOPIC: WOOD
CONTENT:
- Production of Wood Materials, Timber Growth and Felling.
- Properties of good timber preservatives.
- Common timber defects, twist, bowing, cupping, etc
- Methods of cutting veneers
Sub-Topic 1: Production of Wood Materials, Timber Growth and Felling.
Wood is one of the oldest materials in technology. It is composed of cellulose, lignin and other minor materials such as starch, resins, wax and gum. When closely observed, wood is seen to be made up of tiny thread-like units called fibers.
Wood is classified as either hardwood or softwood. The older the tree, the bigger it becomes. When the trees become mature, it is felled by the use of axe or chain saw and sliced into standard market sizes for different purpose in furniture making and construction of buildings.
Hard Wood: These are got from deciduous tree. They have broad leaves and their seeds are enclosed in cases. Some examples include Mahogany, Afara, Opepe, Abura, Omo, Agba, Sapele, Oak, Jarrah and Teak.
Soft Wood: These are got from coniferous trees (i.e. trees that bear naked seeds which are in cones). They have narrow leaves and grow in the temperate regions of the world. Examples include cedar, pine, fir, larch, spruce and European whitewood.
Examples are:
| S/n | Trees | Colour identification | |
| 1 | Iroko | Yellowish brown | |
| 2 | Mahogany | Reddish brown | |
| 3 | Afara | Pale-colour | |
| 4 | Teak | Red-brown | |
| 5 | Yew | Dark- green | |
| 6 | Cotton- wood | Grayish white to light grayish brown | |
| 7 | Hickory | Reddish brown | |
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