Chapter: 11th Botany : Chapter 10 : Secondary Growth
Timber - Secondary Growth
Timber
Timber is
derived from wood logs through the process of sawing. There are many methods of
sawing. Among them,
Timber is mainly used for
carpentry and building houses. In order to enrich the quality of timber,
seasoning of wood is done. Timber is the most important tissue that
sequestrates atmospheric carbon and this reduces global warming.
1. Seasoning of wood
It is the
process in which moisture content from the wood is removed. There are two types
of seasoning.
Air Seasoning is the process in which the moisture can be removed
without resorting to artificial heat. In this method of artificial seasoning,
the cut timber pieces are left exposed in the open air and the moisture is
removed naturally and gradually by the heat of the sun. It increases the
strength, the combustibility and renders the wood less subject to decay.
2. Kiln Seasoning is the
process in which the moisture can be
removed by artificial method in an enclosed condition. The timber pieces are
enclosed in a steam-heater chamber into which air is introduced and circulated
by fans, ensuring the removal of moisture uniformly, rapidly and completely.
2. Grain, Texture, and Figure of Wood
Grain refers to the structural
arrangement of wood, while texture shows the relative size and
quality of the various types of wood. Figure
of wood refers to the pattern formed by grains in wood when the wood is cut
in the longitudinal direction. It depends on the grain and texture and their
exposure by direction of sawing.
Activity
Collect some pieces of plywood, analyse the layers and discuss
yourself how it is made.
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