This document discusses different types of trees and timber. It covers the classification of trees as endogenous or exogenous, with exogenous trees further divided into conifers and deciduous. It describes the structure of trees and the process of seasoning timber to reduce moisture content. Both natural and artificial seasoning methods are outlined. Artificial methods include boiling, kiln drying, chemical and electrical seasoning. The uses, defects, deterioration factors, and methods of preserving timber are also summarized.

1. Submitted By:
Akshay
Isha
Preeti
RAKSHIT

2. INTRODUCTION
Timber denotes wood the organic matter obtained from
trees which is suitable for building or for carpentry and
various engineering purposes

3. CLASSIFICATION OF TREES
:
Trees
Exogenous
Conifers
Deciduous
Endogenous

4. TYPES OF TREES:
ENDOGENOUS :
THE TREES WHICH GROWS INWARDS IN
LONGITUDINAL FIBROUS MASS ARE CALLED
ENDOGENOUS TREES .FOR EXAMPLE :
PALMS BAMBOO

5.  EXOGENOUS TREES :
THE TREES WHICH GROWS OUTWARDS ACROSS HORIZONTAL SECTION
OF STEM ARE CALLED EXOGENOUS TREES .
THEY ARE FURTHER DIVIDED INTO TWO TYPES :
1. CONIFERS or EVERGREEN:
They gives soft wood
They have pointed leaves
for example : sall,devdar,shisam
2. DECIDUOUS :
They gives hardwood
They have broad leaves
for example :teak ,toona

6. TREE STRUCTURE :

7. SEASONING OF TIMBER :
 This is a process by which moisture content in a freshly cut tree is reduced to a
suitable level. By doing so the durability of timber is increased. The various methods
of seasoning used may be classified into:
(i) Natural seasoning
(ii) Artificial seasoning.

8. 1. NATURAL SEASONING :
1. Air seasoning:
 It may be air seasoning or water seasoning. Air seasoning
is carried out in a shed with a platform. Over a period, in a
natural process moisture content reduces. A well seasoned
timber contains only 15% moisture. This is a slow but a
good process of seasoning.
2.Water seasoning :
 Water seasoning is carried out on the banks of rivers. The
thicker end of the timber is kept pointing upstream side.
After a period of 2 to 4 weeks the timber is taken out.
During this period sap contained in the timber is washed
out to a great extent. Then timber is stalked in a shed with
free air circulation.t 300 mm high platform timber balks
are stacked

9. 2. ARTIFICIAL SEASONING :
 In this method timber is seasoned in a chamber with regulated heat,
controlled humidity and proper air circulation. Seasoning can be completed in 4 to
5 days only. The
different methods of seasoning are:
(a) Boiling
(b) Kiln seasoning
(c) Chemical seasoning
(d) Electrical seasoning.

10. TYPES OF ARTIFICIAL
SEASONING :
1.BOILING SEASONING :
In this method timber is immersed in water and then water
is boiled for 3 to 4 hours . Then it is dried slowly. Instead of
boiling water hot steam may be circulated on timber. The
process of
seasoning is fast, but costly.
2.Kiln Seasoning:
Kiln is an airtight chamber. Timber to be seasoned is placed
inside it. Then
fully saturated air with a temperature 35°C to 38°C is
forced in the kiln. The heat gradually reaches inside
timber. Then relative humidity is gradually reduced and
temperature is increased, and maintained till desired
degree of moisture content is achieved.

11. 3.Chemical Seasoning:
In this method, the timber is immersed in a solution
of suitable salt . Then the timber is dried in a kiln. The
preliminary treatment by chemical seasoning ensures
uniform seasoning of outer and inner parts of timber.
4.Electrical Seasoning:
In this method high frequency alternate electric
current is passed through timber. Resistance to
electric current is low when moisture content in timber
is high. As moisture content reduces the resistance
reduces. Measure of resistance can be used to stop
seasoning at appropriate level.

12. ADVANTAGES OF
SEASONED TIMBER :
 It has reduced weight It is strong and durable
 It has resistant to decay or rot It takes high polish
 It is easier to work Its life is more

13. DISADVANTAGES OF
TIMBER :
 Combustible
 Diminish due to rusting
 Destroyed and decayed due to attack of insects ,fungi ,termites etc.
 Timber swells and undergoes shrinkage with changing atmosphere humidity
 Subjected to rot dry rot and wet rot if not seasoned

14. USES OF TIMBER :
 Air dispenser Artificial limbs
 Bakers equipment Balconies, decks and
terraces
 Boat and Ship construction Bee hives
 Cladding Carvings and sculptures
 Cooperage Cabinet making
 Fencing Flooring
 Railway sleepers Windows
 Furniture Glass manufacture Log
cabins
 Musical instruments Construction of houses

15. DEFECTS IN TIMBER :
 (i) Due to natural forces
(ii) Due to defective seasoning and conversions.
(iii) Due to attack by fungi and insects.
(iv) Defects due to Natural Forces: The following defects are caused by natural
forces:
(a) Knots
(b) Shakes
(c) Wind cracks
(d) Upsets

16. (A)Knots:
When a tree grows, many of its branches fall
and the stump of these branches in the trunk
is covered. In the sawn pieces of timber the
stump of fallen branches appear as knots.
Knots are dark and hard pieces. Grains are
distorted in this portion. If the knot is intact
with surrounding wood, it is called live knot.
If it is not held firmly it is dead knot.
(B) Shakes: The shakes are cracks in the
timber which appear due to excessive heat,
frost or twisting due to wind during the
growth of a tree. Depending upon the shape
and the positions shakes can be classified as
star shake, cup shake, ring shakes and heart
shakes

17. (c) Wind Cracks: These are the cracks on the
outside of a log due to the shrinkage of the
exterior surface.
(d) Upsets: This type of defect is due to
excessive compression in the tree when it was
young. Upset is an injury by crushing. This is
also known as rupture.

18. DETERIORATION OF
TIMBER :
 There are so many reasons for deterioration of timber .but there are three main
harmful reasons for deterioration of timber
1.decay or rot 2.insects 3.fire

19. 1.DECAY OR DRY ROT
 Decay or rot of timber is the result of the activity of various bacteria's and fungi ,
which utilize as food ; they require both oxygen excess moisture . Hence timber
having moisture content below 25% will not rot easily .
 Dry rot is wood decay caused by certain species of fungi that digest parts of the
wood which give the wood strength and stiffness. It was previously used to
describe any decay of cured wood in ships and buildings by a fungus which
resulted in a darkly colored deteriorated and cracked condition.

20. 2.INSECTS :
There are so many insects which attacked a wood ,out of
termites (white ants ) are the main insects which are
very dangerous for timber .termites of one class live
under the ground and eat wood and forms tubes and
tunnels inside it

21. 3.FIRE
Fire is also the damaging factor for timber .as timber has
tendency to burn so fire can damage it easily

22. PRESERVATION OF TIMBER
:
 Preservation of timber means protecting timber from fungi and
insects attack so that its life is increased. Timber is to be seasoned
well before application of preservatives. The following are the widely
used preservatives:
1. Tar
2. Paints
3. Chemical salt
4. Creosote
5. ASCO

23.  1. Tar
Hot coal tar is applied to timber with brush. The
coating of tar protects the timber from the attack
of fungi and insects. It is a cheapest way of
protecting timber. Main disadvantage of this
method of preservation is that appearance is not
good after tar is applied it is not possible to apply
other attractive paints. Hence tarring is made
only for the unimportant structures like fence
poles.
 2. Paints
Two to three coats of oil paints are applied on
clean surface of wood. The paint protects the
timber from moisture. The paint is to be applied
from time to time. Paint improves the
appearance of the timber. So lignum paint is a
special paint which protects the timber from the
attack of termites.

24.  3. Chemical salt
These are the preservatives made by dissolving salts in water. The
salts used are copper sulphate, masonry chloride, zinc chloride and
sodium fluoride. After treating the timber with
these chemical salt paints and varnishes can be applied to get good
appearance.
 4. Creosote
Creosote oil is obtained by distillation of coal tar. The seasoned
timber is kept in an air tight chamber and air is exhausted. Then
creosote oil is pumped into the chamber at a pressure of
0.8 to 1.0 N/mm2 at a temperature of 50°C. After 1 to 2 hours timber
is taken out of the chamber.
 5. ASCO
This preservative is developed by the Forest Research Institute,
Dehradun. It consists of 1 part by weight of hydrated arsenic
pentoxide (As2O5, 2 H2O), 3 parts by weight of copper sulphate
(CuSO4⋅5 H2O) and 4 parts by weight of potassium dichromate
(K2Cr2O7) or sodium dichromate (Na2Cr2O7⋅2 H2O). This
preservative is available in powder form. By mixing six parts of this
powder with 100 parts of water, the solution is prepared. The
solution is then sprayed over the surface of timber.
This treatment prevents attack from termites.

25. THANK YOU …