2. 1. Classification and Structure of
a Tree:
1. Exogenous Trees: These Trees increase in bulk by growing outwards
and distinct consecutive rings are formed in the horizontal section of such a
tree. These rings are known as the annual rings because one such ring is
added every year and these rings are used in predicting the age of tree. They
are further divided into two groups:
3. 3
I. CONIFERS: THE CONIFERS ARE ALSO KNOWN AS THE EVER
GREEN TREES AND LEAVES OF THESE TREES DO NOT FALL TILL
NEW ONES ARE GROWN. THESE TREES YIELD SOFT WOODS
WHICH ARE GENERALLY LIGHT COLOURED, LIGHT IN WEIGHT AND
WEAK.
II. DECIDUOUS: THE DECIDUOUS TREES ARE ALSO KNOWN AS
THE BROAD LEAF TREES AND LEAVES OF THESE TREES FALL IN
AUTUMN AND NEW ONES APPEAR IN SPRING SEASON. THE TIMBER
FOR ENGINEERING PROPOSE IS DERIVED FROM DECIDUOUS
TREES.
III. ENDOGENOUS TREES: THESE TREES GROW INWARDS AND
FIBROUS MASS IS SEEN IN THEIR LONGITUDINAL SECTIONS. THE
TIMBER FROM THESE TREES HAS VERY LIMITED ENGINEERING
APPLICATIONS. EXAMPLES – BAMBOO, CANE, PALM ETC.
8. 1.2 KNOTS:
8
• Where a branch has grown out of a tree the grain in the trunk becomes very
twisted. When this is cut through during conversion the result is a weaker
board and one which is difficult to work. Dead knots occur in some
softwoods.
9. • These are
distinguished from
live knots because
they show a black line
round their
circumference and
they sometimes fall
out of the wood
leaving a hole.
1.3 KNOTS:
9
10. 2. SHAKES:
• These are splits along the grain of
the wood.
• Heart shakes and star shakes are
very similar; they radiate from the
centre or heart (see drawing)
10
12. • End splits are
caused by rapid
drying from the
end grain
• Shakes may occur
during the felling
or as a result of
faulty seasoning.
2.2 SHAKES:
12
14. 3.1 DRY ROT:
14
• This is caused by a fungus growth which lives on the wood and
thus destroys it. It attacks wood in damp, unventilated positions
causing it to dry up and crumble into dust.
15. 3. CLASS WORK:
15
Questions:
1.Show by means of sketches what you understand by the following: star shake,
knots, cup shake, waney edge ?
2.Write down what you know about the common furniture beetle ?
3.Name a fungus which destroys wood particular damp unventilated position ?
16.
17. The art of seasoning is to extract the
moisture under controlled condition as
nearly as possible at a uniform rate from
all part of timber and to leave the
remaining moisture that cannot be
extracted uniformly distributed trough
out the mass.
18. • Air Seasoning or Natural Seasoning
• Artificial Seasoning
i. Water Seasoning
ii. Boiling or Steaming
iii. Kiln Seasoning
iv. Chemical Seasoning
v. Electric Seasoning
vi. Smoke Drying
19. As soon as the tree fall, it is converted by sawing
into battens and planks etc. these are then stacked
on a well drain place in shade, care is taken to
ensure free circulation of air all around each piece.
Stacking is done on masonry or concrete support a
few centimeters Above ground. These process of
seasoning timber is the best as it gives very strong
and durable timber, but its is extremely slow. It takes
more than 6 months for timber to season in moderate
climates.
20.
21. i. Water Seasoning
ii. Boiling or Steaming
iii. Kiln Seasoning
iv. Chemical Seasoning
v. Electric Seasoning
vi. Smoke Drying
28. 5. PRESERVATION OF TIMBER
28
• Timber has to be protected from the attach of insects e.g. white ants etc.
and from internal decay due to dry and wet rots.
• Perfect seasoning is the most effective means of preservation. Timber
should be well seasoned before application of preservatives as otherwise
the preservations would block the pores of timber, thereby causing this
decay due to entrapped moisture, Common method of preservation
adopted are :-
29. 29
I. Charring:- Lower ends of posts that are to be embedded
in ground area charged with a view of present dry rot
attack of worms. It is done by quenching the ends of posts
in water after they are charred on wood fire to depth o
1.5cm.
II. Tarring; It consists in coating with tar or tar mixed with
pitch. Embedded portion of timber fence posts, ends of
door and window frames, batters and beams built in wall
area usually tarred.
III. Painting: A paint with applied to timber acts not only as a
good preservative but also it enhances the appearance of
the surface so treated. For e.g. So lignum.
30. 30
(iv) Creosoting: Creosote oil is a dark brown thick oily liquid.
This is done in air tight chamber, after the air is exhausted
from chamber the creosote oil is then pumped at a pressure
of 9kg/sq cm and at a temp of 50 degree Celsius so long as
the timber is not fully saturated with oil. It is used in railway
sleepers. Piles and transmission poles, undesirable color
and smell inability to take paint well and tendency to stain
plaster limit its use.
(v) Wolman salt: This salt consist of creosote and sodium
fluoride and is soluble in water. It is odorless and leaves no
stain on wood. This renders the timber extremely fire
resistant and destroy many kind o fungi.
31. 31
(vi) ASCU Treatment : Forest Research Institute, Dehradun has
developed a new preservative know as ASCU . It is available in
form of powder and is made up of three chemicals mixed in ratio
given below :
1 Part by weight of hydrated arsenic pent oxide (As2O5.2H2O)
3 Part by weight of blue vitriol
(CuSO4.5H2O).
4 Part of weight of potassium
dichromate (K2Cr2O7.2H2O)
Six parts o this powder are mixed with 100 parts by weight of water.
ASCU solution can be applied or sprayed in two coats. This
treated timber may be painted . Varnished, polished or waxed, the
solution is odorless. This render timber immune to the attack of
white ant.
32. 32
Six parts o this powder are mixed with 100
parts by weight of water. ASCU solution can
be applied or sprayed in two coats. This
treated timber may be painted . Varnished,
polished or waxed, the solution is odorless.
This render timber immune to the attack of
white ant.
33. 33
• (vii) Fire proofing of timber :- Making timber fire proof is not
possible , but fire resistant is possible up to sufficient extent.
• Soaking timber is ammonium sulphate, ammonium chloride,
ammonia , phosphate, sodium arsenate,
Zinc chloride, etc or spraying on timber,
a solution of sodium silicate, potassium
silicate or ammonia phosphate etc. Imparts
fire resisting property.
• Abel's method of fire proofing timber is painting the surface first
with a dilute solution silicate (Na2SiO6) then with a cream like paste of
slaked fat lime and in the end with concentrated solution of silicate of
soda.
36. 1. DEFINATION:
DISTEMPERS ARE CONSIDERED TO BE WATER PAINTS CONSISTING OF
WHITING GLUE OR CASEIN AS A BINDER & SUITABLE PROPORTION OF
FAST COLOURING PIGMENTS. THESE DISTEMPER FORM A CHEAP AND
DUARABLE AND EASILY APPLIED DECORATION FOR INTERNAL USE ON
PLASTERED CEMENT CONCRETE AND VARIOUS WALL BOARD
SURFACES.
37. 2. COMPOSITIONS:
A DISTEMPER IS COMPOSED OF BASE (WHITING OR
CHALK ), GLUE(BINDER), WATER(CARRIER OR THINNER
) AND COLOURING PIGMENT. DISTEMPER ARE
AVAILBLE IN VARIOUS SHADES. THEY MAY BE EITHER
IN POWDERFORM OR PASTE FORM . THESE ARE
REQUIRED TO BE MIX WITH HOT WATER BEFORE USE .
40. 3.2 COLOUR DISTEMPER:
• PREPARED BY MIXING DESIRED
COLOUR PIGMENT TO WHITING
BEFORE MIXING IT WITH GLUE
SIZE
41. 3.3 OIL BOUND DISTEMPER (OBD):
• IT IS VARIETY OF OIL
PAINT IN WHICH THE
DRYING OIL IS SO
TREATED THAT IT MIX
WITH WATER. SUCH
DISTEMPERS ARE
DILUTED OR THINNED
WITH WATER WHEN
REQUIRD THEY FORM
ON DRYING A
DURABLE & WASHABLE
COATING.
42. 3.4 CASEIN PAINT:
• PREPARED BY MIXING
A FINELY GROUND
CASEIN (IS EXERTED
FROM MILK, CURD AND
ACT AS A BINDER)
WITH A WHITE BASE
USUALLY SLAKED
LIME. DUE TO HIGH
OPACITY, THESE PAINT
ARE USED ON THE
PLASTERED
SURFACES.
43. 4. PROPERTIES:
DISTEMPER MAY BE FORM OF OIL BOUND
WASHABLE PAINT, WASHABLE OIL FREE DISTEMPER,
NON WASHABLE.
THEY ARE CHEAPER THEN PAINT AND VARNISHES.
THEY ARE TREATED LIKE WATER PAINTS AND HENCE
ARE EASIER TO APPLY.
THEY ACT AS SEALER OVER POROUS SURFACES
AND ALLOW THE WATER TO PASS THROUGH THEM.
THIS PROPERTY PERMITS THE NEW WALL TO DRY
OUT WITHOUT DAMAGING FILMS.
44. THEY ARE MORE DURABLE & PRESENT SMOOTHER.
THEY ARE PREFERRED TO COLOUR WASH AND
WHITE WASH. THEY PROVIDE A GOOD REFLECTIVE
COATING.
46. PROCESS OF DISTEMPERING
• Various steps involved in process of distemper:
1.Preparation of surface
2.Priming coat
3.Coats of distemper
47. PREPARATION OF SURFACE
(1) The new plastered surface should be kept exposed for a
period of two months or so to dry out before
distemper is applied on them. The presence of dampness on the surface results in
failure of distemper coating.
(2) The surface to receive distemper should be free from any efflorescence patches.
These are to be wiped out by clean cloth.
(3) The cracks, holes seen on wall surface should be filled with putty and to allowed
to be becomes hard before distemper is applied on the surface
(4) The old distemper should be removed by scraping and profuse watering before
applying the new distemper.
49. PRIMING COAT
• After proper preparation of surface, The next step is to apply priming coat . it is
allowed to dry .For local made distemper, the milk is used for priming coat. One
liter of milk will cover about 10 m square of the surface.
50. COATS OF DISTEMPER
• The first coat of distemper is then applied on the surface. It should be of a light and
applied with great care. The second coat of distemper is applied after the first coat
has dried and become hard. The distemper should be done in dry weather to
achieve better results.
51. 5. DISADVANTAGES:
5.1:ON DRYING DISTEMPER
FILMS LEADS TO CRACKING
AND FLAKING DUE TO
SHRINKAGE PROVIDE
THAT THE RECEIVING
SURFACE IS WEAK.
53. 5.3: Distemper give poor result in damp place as alternative
wetting and drying cause defects like peeling, flaking and
plastering. distempering should not be done in damp weather.
54. TOPIC: PAINTS
1. The main types of Paints are as following :
• Aluminium paint
• Anti corrosive paint
• Asbestos paint
• Cement paint
• Emulsion paint
• Enamel paint
• Oil paint
• Plastic paint
• Silicate paint
• Synthetic rubber paint
55. (A) ALUMINIUM PAINT
• It protects the iron & steel
from corrosion in better
way.
• Possesses good weather
resisting and water proofing
qualities.
• Due to its brilliant silvery
shining texture it is visible
even in darkness.
• High spreading or covering
power.
56. (B) ANTI CORROSIVE PAINT
• They consist oil; a strong
drier colouring pigment
mixed with very fine sand.
They are cheaper to white
land. It lasts for long period
and give back appearance
to surface
• Used for external work to
protect and preserve
structure steel work against
adverse effect of weather
fumes ,acid corrosive
chemicals etc.
57. (C) ASBESTOS PAINT
• Consists the fibrous asbestos as the
man ingredient of paint. It
possesses the qualities of retarding
the action of fire.
58. C: (A) ASBESTOS PAINT
• Used for painting structural steel
and iron works under water also
used for painting exterior brick and
plastered surface.
59. C: (B) ASBESTOS PAINT
• It is different from ordinary oil
paint and varnish. A cellulose
paint hardens by evaporation
of thinner or solvent used.
60. (D) CEMENT PAINT
• Better water proofing qualities
• Possesses good strength, hardness
density and durability
• It exhibits excellent decorative
appearance.
61. (E) EMULSION PAINT
• Used for brick and
masonry surface which
contain free alkali the
surface to be painted
should first be washed
with zinc sulphate
solution.
62. (F) ENAMEL PAINT
• T dry slowly, but on drying,
it produces a very hard,
impervious, glossy and
elastic, smooth and
durable film over the
surface being painted.
• Enamel painted surface is
not affected by hot & cold
water, steam, acid, alkalis,
fumes of gas etc.
63. (G) OIL PAINT
• This is ordinary paint consist of base
and vehicle may contain others such
as drier, thinner, an inert filler and
coloring pigments.
64. (H) PLASTIC PAINT
• Used for painting showrooms,
auditoriums, offices, cinema
halls etc. where attractive
appearance is desired.
65. (I) SILICATE PAINT
• On drying, forms a very hard
and durable surface.
• Paint has no chemical action.
• No affected by alkali's.
66. (L) SYNTHETIC RUBBER PAINT
• Excellent acid, alkali
and moisture
resistance properties.
• Dries quickly and high
covering power
• Moderate in cost and
can be applied easily
on surface.
67. HEALTH EFFECTS OF VOCS INHEALTH EFFECTS OF VOCS IN
PAINT FUMES:PAINT FUMES:
• There is a wide variety of both short-term and long-term negative health effects
associated with VOCs in paint fumes. The severity of the health effect depends
on several different factors, including both the length of time and the level of
exposure. Some examples of short-term, temporary side effects include:
68. • Irritation of the eyes, nose, throat or and/or respiratory tract
• Visual disturbances
• Headaches
• Loss of coordination
• Nausea
• Lightheadedness
• Dizziness
• Allergic skin reaction
• Fatigue
• Memory impairment
69. • Some of the conditions above can become chronic in individuals who are
consistently exposed to VOCs in paint fumes either in the home or at work on a
daily basis. Long-term health effects of VOCs can include:
• Liver damage
• Kidney damage
• Central nervous system damage
• Certain types of cancer
• Asthma
70. DO VOC’S DISAPPEAR WHENDO VOC’S DISAPPEAR WHEN
PAINT DRIES:PAINT DRIES:
• The odor that emits from paint when it is freshly applied is a result of
the ingredients within the paint that turn it to a liquid substance.
These substances are evaporated into the air while wet paint is
drying. The more wet the paint, the more substances in the air and
the stronger the odor. As the liquid part of the paint continues to
evaporate, odorous paint fumes continue to form. Along with
evaporation comes the process of dispersion.
• Dispersion occurs when the fumes mix with the air and are
dispersed into the environment. As dispersion occurs, more and
more of the fumes are carried throughout the air, which makes them
less concentrated, and the odor less strong. When the fumes are
completely dispersed, the paint is dried entirely and the odor
eventually disappears. VOCs are at their highest concentration
when paint is freshly wet.
