3. Paints:
Paints are used to protect metals, timber
or plastered surfaces, brick work and
concrete work from the corrosive effects
of weather, heat, moisture or gases etc
and to improve their appearance.
Composition of the paints can be easily
adjusted in the process of their
manufacture, depending upon the
purpose for which they are required and
quality of the work required.
4. • CONSTITUENTS/ COMPOSITION OF
PAINTS:
Paints essentially contain a base which
provides body, there is a carrier, also known as
vehicle in which the base is dissolved, and it is
the carrier which helps the base to spread all
over when applied. The pigments are also
added to give the desired colours. Some
common examples of substances used as base
in paint are zinc white, white lead, red lead.
Common substances used as carrier in the
paints is such as, water (in water paints),
linseed oil and poppy oil etc.
Continued -------
5. Besides these essential ingredients, several
other substances are added, such as fillers to
give bulk to the paint without affecting its
properties and to make it economical, solvents
or thinners which dissolve other constituents
and make the paint thin and driers which help
in rapid drying, setting and hardening of the
painted surface. Some commonly used fillers
for paints are chalk, silica and charcoal,
commonly used solvents are turpentine oils,
petroleum sprit, commonly used driers are red
lead, litharge and manganese sulphates etc.
6. USES OF PAINTS:
The main functions performed by paints are:
• It is used to give a high-class finish,
• It is used to give attractive colours,
• It is used to give pleasing surfaces design and
appearance,
• It is also used to protect the material from
atmospheric effects,
• To protect various substances from corrosion,
• To protect wooden articles from wet-rot and many
other types of defects,
• To make the materials long lasting.
7. PROPERTIES OF GOOD PAINTS :
The main properties of a good paint are as follows:
• It should give a thin and uniform coating.
• It should be hard and durable on drying.
• The painted surface should not crack on drying.
• It should be resistant to weathering and corrosive
action.
• It should be water-repellent (except water paints).
• It should have good spread.
• It should have good adhesive power. It should give a
good finish with attractive colour, design and
appearance.
• The colours should be fast and permanent.
• It should be cheap and economical.
9. (1) Oil Paints:
The oil paints are very widely and commonly
used for painting wooden and metallic
surfaces in all kinds of engineering, industrial
and other decorative works. In these paints
various oils like linseed oil, poppy oil and
castor oil etc are used as carrier. These paints
are available in different colours and under
different trade names. While using these
paints it is proper to give two to three coatings
so as to obtain good results.
10. (2) Plastic Paints:
• In addition to other ingredients this paint
contains the requisite amount of plastic.
That is why; all such paints are known as
plastic paints.
• Plastic paints are used wherever high
class work is required, such as
sophisticated buildings, show-rooms,
theatres and auditoriums. They can be
easily applied on the plastered walls.
11. (3)Cement Paints:
• The cement paint essentially consists of White
Cement (about 70%), Hydrated Lime (about 15%),
Pigments (about 5 to 8%), Sodium or Calcium
chloride as the hygroscopic salts (about 5%) and
small amount of about 1% aluminium. These paints
are made available in powder form. Water is added
to the paint just before use. It is necessary to mix
the paint from time to time while using it. The
plastered surface to be painted, like walls etc are
first made wet. As the painted surface dries, water
is again sprinkled over it for proper setting of the
paint.
• Cement paints mainly used over the plastered
surfaces.
12. (4) Bituminous Paints:
Bituminous paints are prepared by
dissolving bitumen in petroleum or
other solvent oil. These black
coloured paints leave hard, tough
and elastic surfaces. These are
highly resistant to water and are
specially used for submerged iron
and steel structures.
13. (5) Water Paints:
A water paint is the mixture of pigment,
binder, drier and water (the carrier).
Casein is the most common binder used
in these paints. A variety of pigments are
used to obtain different colours. These
paints are cheap, easily workable and
also washable when properly set. They
also give a good finish and are suitable
for the inside walls.
14. (6) Distemper Paints:
Distemper consists of chalk (finely powdered),
pigment and glue (animal glue). These are in
powder form and available in a large variety of
attractive shades. Sometimes these are available in
the form of paste also (with the addition of linseed
oil). These are mixed with water at the time of use
and applied on the plastered surfaces (like walls,
ceilings etc) with brushes. These may be
considered as superior quality water paints.
However they give a better finish and are long
lasting. They are suitable for high-class interior
decorative finishing work on the walls and ceilings
of all kinds of buildings.
