Wood is a porous and fibrous material found in trees and plants. It is composed of cellulose fibers and is classified as hardwood, softwood, or fiberboard. Hardwoods come from broad-leaved trees and are dark in color, slow growing, and more expensive than softwoods, which come from conifer trees. Fiberboard is a manufactured wood made by breaking fibers down and bonding them. Wood needs to be seasoned to remove moisture and prevent cracking, shrinking, and fungal growth. Seasoning can be done naturally by air drying or artificially in a kiln for faster drying. Preservatives are treated to wood to protect it from insects and fungi and increase its lifespan. Common preservative

1. Topic

2. wood
• DEFINITION:
“Wood is a porous and fibrous structural tissue found in the stems and roots of trees and
other woody plants”
 It is an organic material a natural composite of cellulose fibers ( which are strong in
tension).
 Classification of wood.
1. Hard wood
2. Soft wood
3. Fiber wood

3. HARD-WOOD:
“Hard woods come from broad-leaved trees (deciduous trees that drop their leaves every
year and produce seeds”
 Hardwood trees are very slow growing trees.
 Hardwood are usually much darker in colour.
 Hardwood is more expensive.
 Example: Walnut,Oar,Cherry,Ash etc
SOFT-WOOD:
“Softwood comes from conifer trees (trees that have needle and do not produce seeds”

4.  Softwood is cheap comparative to hardwood.
 Softwood has faster rate of growth.
 Softwood has low density.
 Example: Pine, Redwood etc.
FIBER-BOARD:
“Fiberboard is an expensive manufactured wood
made from the breaking down of hard on soft
woods into fibers which are then bonded together
with wax, resin and heat to create a dense piece of
wood.

5. CLASSIFICATION OF TREES
•1.Endogenous Tree: One that grow inward in a longitudinal
fibrous mass such as Banana, Bamboo, Palm and Cane. This steam of
these trees is light and tough.
•2. Exogenous Tree: One that grow
outward by the addition of one concentric
ring every year.
like: Deodar, Pine, Shisham etc.

6. GENERAL CHARACTERISTICS OF
WOOD
 Most important characteristic of wood is given below.
1. Colour and Smell:
 Most trees are characterized by a typical colour
and smell.
 Such as walnut wood is distinguished by its typical
dark brown colour.

7.  As regards smell, quite a few kinds of wood are immediately identified.
2. Specific Gravity:
 Wood is a very high material, its specific gravity being
always less than 1 (that of water).
 Wood shows a good deal of variation in their specific
gravity.
3. Moisture Content:
 All woods are poor to some extent .Further, all woods are hygroseopic

8. in nature.
 Moisture content of 12% - 15% of air-seasoned wood is considered
quite safe for timber.
4. Grain:
 By grain it is understood that the arrangement and
direction of grown of the wood elements (tracheids,
fibers and vessels) in the wood.

9. 5. SHRINKAGE AND SWELLING:
 The newly out wood loses moisture when subjected to drying
artificially. on drying the wood
under goes a shrinkage.
 Similarly, dry wood on getting
rain method or wetted may undergo
considerable swelling.

10. 6. Strength:
 The most important fact about the strength of timber is that
it is not the same in all direction.
 This is because wood is an anisotropic
material, having different structure in
different directions.

11. SEASONING OF WOOD
DEFINITION:
• Wood seasoning is defined as : The removal of moisture that is present in the wood
in its green state.
Newly felled tree contain a considerable amount
of moisture. If the moisture is not
removed so the wood is likely to crack and shrink and also
the fungi will attact on it easily.

12. OBJECTIVE/ADVANTAGES OF
WOOD SEASONING
 Seasoning makes wood light.
 It become easier to paint and polish seasoned wood.
 Seasoned wood become stronger and more stable.
 Seasoned stop shrinkage of wood on drying.
 Seasoned wood has better electrical resistance.
 Seasoned wood is more safe against fungi attact.

13. METHODS OF SEASONING
There is basically two method of seasoning.
1.NATURAL SEASONIG.
2.ARTIFICIAL SEASONING.

14.  NATURAL SEASONING
• Natural seasoning OR Air seasoning:
In air seasoning the wood is placed on each other in an
open area in such way that there is a gap between wood
for the air to pass between them. So by evaporation the
moisture will be reduced from the wood after some days.
 Air seasoning can reduced moisture level in the wood
to 10% to 20%.

15. ARTIFICIAL SEASONING
One of the artificial seasoning methods is kiln seasoning .
 KILN SEASONING:
In kiln seasoning we have a chamber which is 100% free from moisture. So
we put the wood in the chamber and increase its teprature so due to the
high temperature the water from the wood comes out and
evaporate and the level of moisture in wood become reduced.
 In kiln seasoning we can control every thing like temperature and
amount of moisture in wood . We can also drop the moisture
level upto 0%.

16. COMPARISON OF AIR
SEASONING(Natural seasoning) AND KILN
SEASONING(Artificial seasoning)
AIR SEASONING
 Simple and cheap.
 Take large area.
 Slow process.
 Hight strength.
 A little low quality.
 Moisture level can decrease to 10%
to 20%.
KILN SEASONING
• Technical and expansive.
• Take small area.
• Fast process.
• A little less strength.
• High quality and safe.
• As desired (moisture level can
decrese upto 0%)

17. PRESERVATION OF WOOD
• DEFINITION:
“All measures that are taken to ensure along life of wood is known as
preservation of wood”.
 We use preservatives for preservation.
 Chemical compound that injected into the timber or wood
to make it poisonous for insects or fungi without altering
the structural properties of wood.
 preservation used for maintaining useful life of wood.

18. TYPES OF PRESERVATION
Following are the types.
 OILY SUBSTANCE:
 Coal tar best preservative.
 Obtained from bituminous coal.
 Used to control wood degradation problem.
 In soluble in water hence used as permanent
preservative.
 Highly toxic for fungi and insects.

19.  WATER SOLUBLE PRESERVATION:
 Zinc chloride mainly used.
 Easily available, clean, odorless.
 Other water soluble preservatives chromatid copper
assenate, acid copper chromate, ammonical copper
assenate, ammonia soluble zinc copper assenate etc.
 SALTS:
 Asch is mainly used.
 Copper and aseric compounds used as preservative.
 Good fire resistant so can protect from fire.

20. METHODS FOR PRESERVATION OF
TIMBER
• Methods for preservation of timber are:
 Timber must be fully seasoned before preservation.
 CHARRING:
 Lower ends of posts that are embaded
generally charred.
 To prevent from rotting and worms attack.
 Done by quenching the ends of posts.

21.  TARRING:
 Use tar for coating.
 Embedded portion of timber fence posts.
 Tarring at ends of doors and window frames.
 Beams can also be tarred.
 PAINTING:
 Acts as preservation.
 Increases the appearance of treated surface.
 Only well seasoned timber is painted.

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