Seasoning of timber:
Seasoning of timber is done to reduce the moisture content in the wood to make so that it becomes suitable for various purposes. It is necessary to remove moisture content before working on wood to prevent it from defects like shrinkage, warping or twisting etc.
Advantages of Seasoning:
- Wood becomes hard and durable.
- Workability of wood is improved.
- Defects like shrinkage, warping, bowing, twisting and splitting, do not occur after seasoning.
- Ability for taking up painting and polishing is improved.
- Resistance to fire is increased
Methods of Seasoning:
There are mainly two methods of seasoning:
1 – Natural seasoning: There are two methods of Natural seasoning.
A. Air seasoning: The balks of timbers are placed on a platform (about 30 to 40 cm high) under a shed to prevent them from direct sun and rain. They are placed in such a way that free circulation of air takes place through them. Proper arrangement of drainage is made. The balks should be periodically turned upside down for proper and fast drying. The drying period can be from 1 to 5 years depending upon the type of wood.
B. Water seasoning: The balks of timber are immersed in flowing water for 2 to 3 weeks. The flowing water removes the sap from wood. The timber is taken out from the water and air seasoning is done in the usual way.
2 – Artificial seasoning: In artificial seasoning, following methods are generally used
A. Kiln seasoning: The balks of timber are kept in hot chambers called Kilns. They are dried in these chamber under controlled conditions of temperature and humidity with proper circulation and ventilation system. This method enables the seasoning at a faster rate but quality of wood obtained is of inferior quality as compare to the wood obtained through natural seasoning.
B. Chemical Seasoning: The timber is immersed in a soluble salt solution. The salt solution absorbs the moisture from the timber. It is taken out from solution and seasoning is done in usual way.
C. Electrical seasoning: The process is based on the principle that when poor conductor is placed in the field of high frequency, heat is produced. The timber is subjected to alternating current having high frequency. Due to induction effect the moisture in the timber is dried out quickly.