DEFECTS IN TIMBER
You have understood the tree, its classification and structure. Now let us study the Defects in timber. As hum body has many defects, timber also have defects. These are grouped into the following five divisions:
1) Defects due to conversion
2) Defects due to fungi
3) Defects due to insects.
4) Defects due tonatural forces
5) Defects due to seasoning Now,
let us know various
types of defects under each category:
Defects due to Conversion, During the process of
converting timber to Commercial form, the following defects may occur:
i) Chip mark
ii) Diagonal grain iii) Tom grain
iV) Wane:
This defect is indicated by the marks or signs placed by
chips on the finished surface bf timber. They may also be formed by the parts
of a running machine. Diagonal Grain: This defect is formed due to improper
sawing of timber. It is indicated by diagonal mark on straight grained surface
of timber. Tom Glain: This defect is caused when a small depression is formed
on the finished surface of timber by falling of a tool or so. Wane: This defect
is denoted by the presence of original rounded surface on the manufactured
piece of timber.
Defects due to Fungi Fungi ate minute microscopic
plant organisms. They attack timber only when the following two conditions are
satisfied simultaneously.
i) The moisture content of timber
ii) There is presence of air and warmth for the growth of
fungi. If any of the above condition is assert, decay of wood due to fungi
would not occur. Hence, &y wood having moisture content less than 12-1496
will remain sound for centuries. Similarly, wood submerged in water win not be
attacked by fungi because of absence of air. Following defects are caused in
timber by fungi i)i Blue stain ii) Brown rot
iii) Dry rot
iv) Heart rot
v) Sapstain
vi) Wet rot has twisted out of shape; it is said to have warped.
This will be upadated soon as possible
