Properties of materials – wood

Definition of Materials

Materials are substances from which other things can be made. Basically, they can be classified into two: metallic and non-metallic. Furthermore, the metallic ones can be subdivided into ferrous and non-ferrous metals, while the non-metallic ones can be divided into natural and synthetic materials.

The Definition of Wood

One of the materials that is supplied by nature is wood. Wood is commonly used in some engineering manufacture because it is light, strong and can be worked upon easily.

Wood is a material obtained from trees. It is made up of cellulose and lignin each consisting of 60% and 28% respectively.

Identification of Wood

Generally, wood has very good combination of colours to give it high decorative value. This makes it possible to identify some woods by their colour. Examples are:

Classification and properties of wood.

There are two types of wood tress.

1. Hardwood (deciduous) Trees

Differences in the Properties of Hardwood and Softwood


S/N	HARDWOOD	SOFTWOOD
1	They are derived from deciduous trees.	They are derived from coniferous trees.
2	They have broad leaves.	They have needle-like leaves.
3	They shed their leaves once every year to prevent water loss.	They have ever green leaves.
4	The hearts of hardwoods are heavy.	The hearts of softwoods are light.
5	The seeds are enclosed in case or shell.	They have naked seeds.
6	They produce timbers for furniture e.g.: Iroko, Afara, Ekki, Oak, Mansonia, Mahogany, Obeche, Omo, Opepe.	They are produced for commercial uses. Examples are: Spruce, Yew, Larch, Pines, Cedar, Redwood, Whispering tree.
7	They are grown mostly in tropical regions.	They are grown mostly in temperate regions.

Properties of Materials and Identification of Wood, Timber, Structure of Wood

Felling of trees can be done in two places: Free Areas and Forest Reserve.

Free area is one that is owned by individual. Trees can be cut down thereafter consulting the owner, but the contractor will pay certain amount of money through forest guard to the government, this is called ‘Tariff’.

A forest reserve is a very large area of land owned by the government. The wood can only be cut down there when getting approval from the government.

The company usually bought tree from forest reserve. The timber contractor pays for the total volume of timber taken out. The money paid is known as O.T.V i.e. Out Turn Volume.

The Growth of Timber and Wood Structure

The tree need food to grow, this food is absorbed by the roots in the soil. It passes through the sapwood to the leaves where chemical reaction takes place through the sunlight. The food will now be transferred to the tree through the blast.

Five Main Parts Cross Section, Classes and Properties

The five main parts of a tree are:

Root:It searches for various mineral salts in the moist ground. It also holds the tree firmly in the ground.
Trunk or Stem:is the part that acts as a support for the branches which rises as high as possible towards the light. It is from the trunk that we get our timber.
Branches:develop as leaves.
Leaves:These manufacture food for the tree through the action of sunlight and air.
Bark: protects the growing part of the tree from the weather, animals and any other injuries.

The features of the cross-section of a tree when felled are:

The Cambium Layeris actual living part.
Sapwoodis active part of tree.
Heartwoodis the mature part of the tree.
Pith:The Central core of the trunk
Medullar Raysare food storage cells.

EVALUATION

How many classes of wood do we have?
Name three examples of Hardwood tree.
Mention two features of Softwood.

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