Category: Timber & Industrial Timber Products

There are three types of preservatives with different bases as prescribed in the Code (IS: 401–2001). 1. Oil Types In this type coal tar creosote with or without admixtures of soluble oils is used. 2. Organic Solvent Types These are toxic chemicals in non-aqueous solvents such as copper napthenate, zinc napthenate, benzene hexachloride, etc. 3. Water-base Types…

A good preservative should fulfil the following requirements:

To increase the life span of wood, they should be treated with chemicals–this process is known as the preservation of timber.

Once the woods get deteriorated they lose their engineering properties and the wood is said to be decayed. Several reasons contribute to the decay of wood, which are explained below:

There are two broad approaches to seasoning, viz., 1. Natural Seasoning There are two methods of natural seasoning, viz., air seasoning and water seasoning. (i) Air Seasoning It is also known as air drying. In this method timbers intended for seasoning are stacked in a dry place under cover about 30 cm above the floor…

Although the primary aim is to remove sap and moisture, the other objectives of seasoning are as follows:

Trees felled recently will contain large amounts of sap and moisture. Seasoning is the process of removing all the sap and moisture content under controlled conditions to avoid any splitting and distortion in the wood.

This is the method adopted for sawing hardwood. This method of sawing produces planks, which do not shrink much. Because of the interplay of grains, it gives a decorative finish. However, maximum wastage occurs by this method of sawing.

The disadvantage mentioned in ordinary sawing is to some extent avoided in quarter sawing. This method of sawing produces fine timber when the wood has no distinct medullary rays. However, timber cut by this method has a tendency to get bent in the transverse direction (Fig. 10.7(a)). Figure 10.7 Ordinary and quarter sawing

In this method of sawing the log is simply sawed along the diameter. This is the quickest and commonly adopted method. This approach is more economical as wastage of useful timber is minimum. Each cut plank has an outer portion of sapwood and an inner portion of heartwood. But there will be differential shrinkage and…