JSS2 Basic Technology Lesson Note on Wood

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TOPIC:                     WOOD

CONTENT:

1. Production of Wood Materials, Timber Growth and Felling.
2. Properties of good timber preservatives.
3. Common timber defects, twist, bowing, cupping, etc
4. 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

Tree Growth: Trees undergo two types of growth:

1. Primary or vertical growth. This takes place mainly near the tips of the root and shoots of the tree and continues for the most part of the plant’s life.
2. Secondary or horizontal growth. This results in increase in girth and takes place mostly in the cambium.

The stages of processing wood before becoming useful are:

1. Felling
2. Conversion

• Seasoning

1. Preservation.

TYPES OF TREE:

• Deciduous Tree = Hard wood
• Coniferous Tree = Soft wood

THE MAIN PARTS OF A TREE.

• The Roots
• The Stem / Trunk
• The branches
• The bark
• The Leaves

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