Seasoning of timber

seasoning of timer. the process of seasoning, types of seasoning , advantages of seasoning

1. Seasoning of timber Patel Aashvi Patel Bhakti Patel Harshika Patel Kajal Sub. Faculty: Vaishali Patel Falguni Rathod

2. Seasoning of timber Definition of seasoning Natural seasoning Artificial seasoning Kiln seasoning Chemical seasoning Electrical seasoning Seasoning by boiling Water seasoning

3. What is seasoning? Seasoning of timber is the process of lowering down the natural moisture content of timber, seasoning should be planned in such a way that evaporation of water from the outer layers and the movement of water from the interior to the outer surface is balanced. Moisture should be removed at a uniform rate and the moisture that cannot be removed remains uniformly distributed throughout the mass as far as possible, irregular drying , setup internal stresses which may cause defects like warping, shake, etc

4. Advantages of seasoning: Seasoning makes timber resistive against decay due to borers, termites, fungi etc . Reduces weight of timber and hence saves cost of transportation . Makes timber stronger, stiff and hard makes timber receptive for paints, varnishes and preservatives Reduce shrinkage of timber Makes timber easily workable Reduces chances of warping and cracking of timber increases resistive power of timber against electricity Timber can be easily used as fuel Increases durability of timber

5. Preparation of natural seasoning: It is not possible to season the timber in log form. Logs are cuts and sawn to suitable sections. Ends of logs or planks should be painted with tar, asphalt, paraffin wax, sealing liquid to avoid splitting at ends. Pillars about 300 mm height and 300 mm square are constructed at about 1200 mm intervals out of bricks or stone masonry or concrete. Top of all the pillars should be at same level. Long beams of 100mm x 100 mm are placed on the pillars, to form framework for stacking timber. Timber pieces are assembled and arranged in layers one above the other. All pieces in one layer should have same thickness to avoid changes to warping or cracking. Stacks should be protected from rain, wind heat of sun. a roof of suitable material should be provided at the top.

6. Advantages Requires minimum supervision Economical Suitable for thick as well as thin sections. Draw backs Process is slow. Takes 1 to 4 for seasoning. No control over natural air. Moisture content can not be brought to desired level Drying is not uniform More space is required.

7. There are two main types of kiln used in artificial seasoning Compartmental kilns Progressive kiln Both methods rely on the controlled environment to dry out the timber and require the following factors : Forced air circulation by using large fans, blowers, etc. Heat provided b piped steam Humidity control provided by steam jets The amount and duration of air, heat and humidity again depends on species, size, quantity, etc. in general, the atmosphere in the kiln at first will be cool and moist. The temperature is gradually increased and the humidity reduced until the required moisture content is achieved. Kiln seasoning

8. Chemical seasoning: It is the preliminary treatment given to the timber before kiln seasoning. Sodium chloride, sodium nitrate, urea are used. These chemicals reduce vapour on the surface of application. Hence wood surface remains moist while moisture from inner portion diffuses towards surface. Timber dries first from inside, hence chances of cracking are reduced. After application of chemicals timber is seasoned as usual.

9. Electrical seasoning: When high frequency electric current is passed, through a piece of green timber, resistance offered by green timber is less. On drying of timber the resistance increases which generates more heat. Timber pieces are dried quickly. This process consumes more electricity, requires costly equipment and reduces strength of wood. It is not economical.

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