Timber Identification & Wood Preservation
Research Work Carried out in Biology Division : Timber Identification
Timber Identification is a highly specialized and fascinating field of study. The timber which means wood of commercial importance is one of the most valuable and versatile raw material used by man and plays a vital role in the economic and industrial development on a nation.
In India alone we have well over 1600 different wood species, which show a remarkably wide range of variation in their physical properties as well as in their anatomical structure.
Based on the presence or absence of pores timbers are classified under two main groups, porous and non porous.
Porous Wood: porous wood are produced by dicotyledonous or broad level trees. Example: Teak, Sal, Mango, Semul etc.
Non porous woods: Non porous woods are produced by coniferous or needle leaved trees.
Example: Deodar, Chir, Spruce and Fir etc.
Non Porous Timber
The first step in the in identification of any unknown sample of wood is to examine it carefully and observe its important anatomical and other characteristics. This is usually done with the help of trinocular research microscope (image analysis software).
Wood being an organic material is liable to be attacked by biological agencies. The principal agencies of wood deterioration are fungus and insects.
Fungi causing damage to timber are mainly mould, sapstain, and decay, which are briefly mentioned below.
Moulds are superficial surface growths and are useful in indicating localized damp conditions conducive to fungal decay. They occur on the surface of timber with wooly or powdery appearance.
Sapstains as the name implies, discolor the wood. The fungi causing sapstain have coloured hyphae. Fungi take food from the stored sugar and starch in the wood and are incapable of utilizing lignin and cellulose.
Wood rot or Decay Fungi:
Wood rotting fungi are sub-divided into three main groups
a. Brown rot Fungi: Brown rot fungi utilize only cellulose but highly change the structure of the lignin and turn it brown that is why known as Brown rot fungi.
Example: Poia monticola etc.
b. White rot Fungi: Attacks all component of wood, i.e. cellulose, hemicelluloses and lignin and as these components are removed from the wood it becomes bleached and hence called as white rot fungi.
Example: Polyporous versicolor, etc.
c. Soft Rot: They grow on wood in damp environment. Mostly seen on wooden window frames, the timbers of cooling towers and wood in marine environment.
Example: Cadophora spp. etc.
The most important group of insects belong to the order coleopteran (beetles) and isopteran (termite). Different group of insects which attack timber are as follow:
Ambrosia beetle (Pin-hole borers/ shot hole borers):
Flat-headed borers and long horn beetles:
Powder post beetles:
They are the biggest destroyers of wood and wood products in the world.
Dry wood termites:
Preservation of timber
With the increase in use of plantation timbers like Poplar, Rubber wood, Silver oak and other farm grown timbers service life of wood composites like plywood, block board, flush door has been found to be lower compared to similar produces made from traditional forest tree species. This is due to the fact that timber from many fast growing tree species is susceptible to attack by borers, termites and fungi.
However, incidences of attack by the wood destroying organisms can be prevented by incorporating suitable chemical treatments in the process of manufacturing various panel materials including plywood, block boards, and flush doors. IPIRTI has done extensive research on these aspects and also for treatment of plywood/block board/flush door, which can be easily adopted by the industry for manufacturing quality products.