Wood Seasoning and importance and Methods of Seasoning

What is Seasoning? Write down the importance of seasoning of timber and methods of seasoning.

Wood Seasoning

During the process of wood seasoning, moisture contained in the wood is taken away and thus the timber gets rid of sap. If the sap is not removed, timber is likely to shrink, crack and warp after sometime. decaying may also occur. The object of seasoning are,

(a) To add Ii durability, work ability and strength.

(b) To reduce its weight by taking off the moisture.

(c) To reduce the tendency to shrink, split, warp and rot.

Methods of Seasoning

There are two common methods of seasoning.

(1) Natural Seasoning

(2) Artificial Seasoning

(3) Natural Seasoning

This method is also called “Air Soasoning”. The rough out logs should be dried slowly by stacking them as shown in the figure below. These should be kept a little above the ground, so the free circulation of air should take place. The drying shed should be well-drained and properly roofed to save the logs from the high winds and direct sun rays. This is the best method but it takes a long time say two to four years.

AritifiiaI Seasoning

Artificial methods have been adopted to season the wood more

rapidly.

Following are the few methods.

(I) Water Seasoning (ii) Boiling

(iii) Chmica1 or Salt Seasoning

(iv) Kiln Seasoning (v) Electrical Seasoning

(i) Water Seasoning

In this method the timber is immersed in water as soon as it is cut. It is kept In water for a fortnight and then it is taken out and dried in open air. By this process the timber is less liable to warp and crack. The strength is weakened. This method is beneficial to the wood which is very green and full of sap.

(ii) Boiling

Timber is kept in boiling water or steam for about four hours. Then it should be dried slowly not rapidly. This method increases the strength and elasticity of timber.

(iii) Chemical or Salt Seasoning

In this method the green timber is soaked in saturated salt solution and then taken out and seasoned in an ordinary way by keeping in open and airy place. It is only a surface dipping that is effected, the interior moisture is drawn out first and then outside is dried, the external splitting reduced.

(iv) Kiln Seasoning

This method is considered to be the best method amongst artificial seasoning methods. The timber is exposed in a chamber or kim to a current of hot air. In this method the steam at low temperature is passed through the stack of timber. The air at higher temperature is followed to take off the moisture which is absorbed in the timber and also of steam. In above figure gives an idea ho. The stack of timber is pushed on trolley in the kim. The passage of steam and hot air also shown. This method is called Desicating Process also.

(v) Electrical Seasoning

In this method high frequency alternating current (known as di-electric heating) is used. This method has been found best for plywood manufacture. But the cost of apparatus of electricity is very high so it is seldom used.