Seasoning timber and wood is essential as we can’t use freshly cut trees. In this article, we’ll discuss the seasoning of timber, its methods, and its purposes.
What Is Seasoning Of Timber?
Timber is a wood product that is used for building, carpentry, or various other engineering purposes. Water in the form of sap and moisture makes up around half of the dried weight of wood collected from newly felled trees.
This water should be removed before timber is used for building works. The process of removing this water content or drying the timber is called the seasoning of timber.
Moisture should be removed from all sections of the timber consistently and under regulated conditions. Irregular shrinkage occurs as a result of irregular drying, causing internal tensions to form between the fibers. Timber may warp if these stresses become too great. As a result, uniform drying is essential.
Purpose Of Seasoning Of Timber
i) To make it easier for timber to burn when used as fuel.
ii) Lower the cost of shipping and handling by reducing the weight of the timber.
iii) To protect the timber from fungal and insect infestations.
iv) To lessen the likelihood of wood cracking, shrinking, or warping.
v) To prepare timber for painting, preservation, and varnish treatments, among other things.
vi) To give wood more hardness, stiffness, strength, and electrical resistance.
Methods Of Seasoning Of Timber
There are two methods of seasoning. They are
- Natural seasoning
- Artificial seasoning
1. Natural Seasoning
Natural seasoning of timber is carried out by normal air, and therefore it is also called air seasoning. In this process, the timber pieces are either stacked horizontally or vertically.
The horizontal stakes are common and better. The ground on which the stacks are built should be precisely leveled. The platform should be 30-50 cm above the ground.
Sometimes rows of bricks or concrete pillars are constructed. The timber pieces are placed horizontally in layers one above the other. Dry wood spacers are used to divide each layer.
They are protected from blowing wind, rain, and extreme heat of the sun. Therefore, a suitable roof cover is very essential for this type of seasoning.
i) The moisture content can be brought down to about 10-20%, depending on the climatic condition.
ii) It does not require skilled supervision.
iii) This method of seasoning is both inexpensive and simple.
iv) Artificial seasoning of timber parts thicker than 100 mm is uneconomical since such sections take longer to dry.
i) Because the process is dependent on natural air, it can be difficult to control.
ii) Different surfaces may not dry evenly and uniformly.
iii) If ends of thick sections of timbers are not projected by suitable moisture-proof coating, then there are chances for end splitting because the end of such timber dries rapidly in comparison to the central portion.
2. Artificial Seasoning
Chemical, electrical, kiln, and water seasoning are all examples of artificial seasoning. The following are the reasons for switching from natural to artificial seasoning:
- Shrinkage, cracking, and warping are all reduced to a minimum.
- The drying process is controlled, and fungi and insects have almost no opportunity of invading.
- The drying of various surfaces is even and consistent.
- It considerably reduces the period of seasoning.
- There is better control of the circulation of air, humidity, and temperature.
- The timber becomes more suitable for painting and gluing.
Various methods of artificial seasoning of timber are:
i) By Boiling
In this method of artificial seasoning, the timber is immersed in water, and water is then boiled for 3 to 4 hours. Because boiling a big quantity of wood is difficult, heated steam is occasionally piped through the logs in an enclosed space.
It also produces positive outcomes. The boiling or steaming process increases the strength and elasticity of wood, although it is more expensive.
ii) Chemical Seasoning
It is also known as salt seasoning. The wood is submerged in a sufficient salt solution in this process. The salt solution has a proclivity to absorb water from the wood. As a result, the moisture content is reduced, and the wood is allowed to dry.
It has an impact on the wood’s strength. Because the inside surface of the wood dries before the exterior, the chances of external crack formation are minimized. The salt solution has a proclivity to absorb water from the wood.
iii) Electrical Seasoning
It is the most rapid method of seasoning. In this method of seasoning, high-frequency alternating currents are used. The resistance of wood to electricity is measured at regular intervals.
Seasoning is stopped when the required resistance is obtained since the resistance of timber increases as the moisture content in it decreases. Another name for electrical reasoning is rapid seasoning.
However, the initial and ongoing costs of this process are so expensive that it is uneconomical to season timber commercially using this method.
iv) Kiln Seasoning
The drying of wood is done in an airtight chamber or oven in this procedure. Air that is fully saturated with moisture and which is heated to a temperature of about 35 to 38 is then forced inside the chamber by suitable arrangement.
The hot air flows between the timber logs, lowering the moisture level. Heating coils are used to raise the temperature inside the chamber. Moisture content and relative humidity are reduced as the required temperature is reached, and the timber is seasoned.
It is expensive and quite technical. Insects and fungi are less likely to attack kiln-seasoned wood. The moisture content of timber can be reduced to any desired level. It is a quick process.
v) Water Seasoning
The timber pieces are completely immersed in water, usually running water from a stream, in this process of seasoning. It’s important to make sure that the wood isn’t partially submerged.
On the upstream side, the thicker or larger end of the timber is kept pointed. After a period of 2 to 4 weeks, the timber is removed. During this period, sap contained in timber gets washed away by water.
So these were the methods of seasoning timber. I hope you now have enough knowledge about it. If you have any questions, let us know in the comments.