What is Seasoning of Timber?

What is Seasoning of Timber?

Removal of moisture from timber so as to be in equilibrium with the moisture in surrounding atmospheric condition, where timber is likely to be used is called the seasoning of timber. In other words, seasoning of timber means getting rid of the sap and moisture from it. After seasoning has been done timber is not liable to be delayed. After seasoning, the timber becomes dry, hard, light in weight, less in bulk and resilient. There is a different method of seasoning like

1. Natural Seasoning
2. Artificial Seasoning

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  The function of Seasoning of Timber

The seasoning of timber is performed to achieve the following purpose:
1. To impart hardness, stiffness, strength and better electrical resistance to timber.
2. To make timber easily workable and facilitate operations during conversion.
3. To maintain the shape and size of the component of the timber article which is expected to remain unchanged in shape.
4. To reduce the tendency of timber to crack, warp and shape.
5. To make timber safe from the attack of fungi and insects.
6. To make timber suitable for glueing i.e. effectively joining two members of timbers of timber with aid of glue.
7. To allow timber to burn readily when used as fuel.
8. To make timber fit for receiving treatment of paints, varnish, preservatives etc.

Natural Seasoning
There are two types of natural seasoning.

a.) Air Seasoning:- It is the best method of seasoning. In this method, water or moisture is driven out from the timber by a very slow process of evaporation. The object of seasoning is to ensure regular and uniform drying all throughout the timber.

b.) Water Seasoning:- in this method logs are kept immersed in ponds or in running streams with the root ends upstream for three to four weeks. Maximum sap is washed out by this process. The logs should be kept entirely down under water by chaining them. Now after that, these logs are kept under the shed for free air circulation.

Advantages of Natural Seasoning of Timber

Following are the advantages of the natural seasoning of timber:
1. Depending upon the climatic conditions, the moisture content of wood can be brought to about 10 to 20 %.
2. It does not require skilled supervision.
3. It is uneconomical to provide artificial seasoning to timber sections thicker than 100 mm, as such sections dry very slowly
 Hence such thicker timber sections are usually seasoned by the process of air seasoning.
4. This method of seasoning timber is cheap and simple.

Artificial Seasoning
There are different methods of artificial seasoning.

a.) MC Neills Seasoning:- this is to be the best method of artificial seasoning, as it has no adverse effect on the appearance and strength of the timber. The time required varies with the nature of timber, usually 15 days to two months. Timber seasoned by this method is rendered hardened, denser and proof against dry rot. But it is a costly method of seasoning timber.

b.) Hot Air Seasoning:- This process is also known as kiln seasoning. It renders timber brittle and bleaches deep coloured timber.

c.) Seasoning by Boiling in Water:- Water seasoning can be done by using boiling water. The timber is kept immersed in boiling water for four hours, by this method strength and elasticity of the timber reduced, although there is less shrinkage.

d.) Seasoning by Steaming:- This is similar by boiling but the timber dries soon after the steaming. Steaming prevents dry rot in timber, but it is expensive.

e.) Chemical Seasoning:- The chemical seasoning is also known as salt seasoning. In chemical seasoning, the timber is immersed in a solution of suitable salts. The interior surface of timber dries in advance of exterior one and chance of formation of external cracks are decreased.


f.) Electrical Seasoning:- In this type of seasoning, The high-frequency AC currents are used. The green timber offers less to flow electric resistance currently. As the wood dries internally the resistance raised that also results in the production of heat. This is the most rapid method of seasoning, but higher initial and maintenance costs.


Comparison Between Natural Seasoning and Kiln Seasoning

S.No.
Item
Natural Seasoning
Kiln Seasoning
1.
Moisture Content to 18%
It is difficult to reduce the moisture content below level.
The moisture content can be reduced to any desired level.
2.
Nature
It is simple and economical.
It is expensive and quite technical.
3.
Quality of timber
The air seasoned timber is more likely to the attack of insects and fungi.
The kiln seasoned timer is less liable to the attack of insects and fungi.
4.
Space
It requires more space for stacking.
It requires less space for stacking
5
Speed
It is a slow process.
It is quick a process.
6
Strength
It gives stronger timber.
It gives a little weaker timber.





Read More - Requirements of Good Quality Timber

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