Paint is defined as a mixture of binder, pigment, and additives that forms a solid film after drying. Pigments impart color and protect the film from radiation like UV rays. Paints can be classified by their application, such as house paints, wall paints, marine paints, and more. The main constituents of paint are pigments, extenders, film formers, driers, thinners, and others. Pigments protect the film and extenders decrease costs. Film formers form the protective coating while driers and thinners control the drying process.

1. “Paint is defined as a unique homogeneous mixture of three
major ingredients namely Binder, Pigment, VOC & additives, which
when. applied on the surface as a thin layer that forms a solid dry
adherent film after oxidation/evaporation/ polymerization. Paints are
stable mechanical mixture of one or more pigments. The main function
of the pigments is to impart the desired color and to protect the film
from penetrating radiation, such as UV rays.
On the basis of their applications, paints can be classified as i. Exterior
house pants, interior wall paints, Fire resistance paints, chemical
resistance paints, luminous paints, marine paints, emulsion paints,
latex paints, aluminum paints, metal paints, and cement paints.
Constituents of Paints: The main constituents of paints are pigments,
extenders of fillers, film forming materials, driers, thinners or
diluents, antiskinning agent, plasticizer, resins, blinders, extenders
and other compounds.
Santanu Sir

2. Functions of constituents:
Pigments: They protect the film by reflecting the destructive ultra violet light to strengthen
the film.
Extenders of fillers: The extenders or fillers are added to the paint in order to decrease the
cost of the paint and to supplement the pigment in increasing the covering and weathering
power of the film.
Film forming materials: They act as carriers for the pigments and as formers of the protective
film.
Driers: It is used in order to accelerate the drying of the film through oxidation and
polymerization.
Thinners: Thinner id also added to the paint in order to dissolve film forming material and
to thin concentrated paints for better handling.
Antiskinning agent: Certain antiskinning agents are added to the paint in order to prevent
gelling and skinning of the finished product before application of the paint by brushing.
Plasticizers: Plasticizers are added to the paint by proper choice of the oils. Plasticizers
provide elasticity to the film and thus cracking of the paints.
Resins: Resins are not essentially required for oil base paints. Water base paints contain no
oils and depend on vinyl acetate, acrylic, stryene polymer resin as the film forming materials.
Binders: Binders act to fix the paint on the coated surface and provide tough, tenacious and
glossy film on the surface being painted.

3. Paint Failure: The failure of paints may be due to various
causes, and in each case there is a special term used to
explain the failure. Progressive chalking or powdering of the
paint film is called chalking and is caused by the destructive
oxidation of the oil after drying of the paint on the surface. If
chalking is very rapid, the term erosion is used. Poor
attachment of the paint on the surface to be coated is called
peeling. If the center portion remains attached to the surface
and the portion around the centre peels off, a term
alligatoring is employed. Fine surface cracking is called as
checking and is due to the absence of plasticizer in the paint.
Paint failure can be avoided by (a) careful mixing of the
constituents or ingredients in specified proportions (b) proper
processing of the surface to be coated before the paint is
applied and (c) using a primer coat before the application of
the paint.

4. Emulsion Paints: Emulsion paints are those paints in which water is
used in place of organic solvents as thinner. Emulsion paint is an
emulsion of two phases, one of which is water and this paint can
readily be diluted or thinned with water, because water is the
continuous phase present in it.
The pigments and extenders mostly used in emulsion paints are
water dispersing titanium dioxide, zinc sulphide, clay diatomaceous
silica, magnesium silica, mica etc. Coloured pigments may be used
for tinting. Water dispersible oil such as linseed oil has widely used
in emulsion paint.
Advantages: Emulsion paints can be applied on the surface on the
surface of metal or wood very easily and they are quick drying low
odor, more durable and more impermeable to dust and dirt. These
paints can be very easily applied with brush or roller and after
painting, the brush or roller can be easily washed with water.

5. Eco-friendly Paints: It should mean that a product has no
detrimental effect on the environment or society. Modern paints
are stretching credulity claiming this when they are derived in
large part from petrochemicals. They are not “water-based” so
much as they have water added – and it may not be in large
amounts. Natural paints are products driven by ethical principles
that ensure responsible sourcing, controlled processing, no
hazardous waste and carbon neutrality in their manufacture.
Today, an emerging alternative to chemical solvents are eco-
friendly paints. These use water-based solvents to reduce or
eliminate the release of VOCs in indoor spaces. Plus, they're
odour-free and have a significantly lower impact on the
environment.’

6. Pigments are various organic and inorganic insoluble substances, which are
widely used in surface coatings. They are also employed in ink rubber,
ceramic etc.
Pigment volume concentration: Pigment volume concentration (PVC) is simply
defined as the fractional (or percentage) volume of pigment in the total
volume solids content of the dry paint film: PVC=VpVp+Vb where Vp =
pigment volume and Vb = binder volume.
Critical Pigment Volume Concentration: CPVC is the abbreviation for critical
pigment volume concentration. CPVC is the pigment concentration where the
pigments are packed as close as possible and the binder is exactly the
amount required to fill the space between the pigments. When formulating
paint, the PVC should normally be lower than the CPVC.

7. Metal Spraying: In this process, coating metal in the form of molten
state is sprayed on the roughened surface of the base metal by
means of a portable spraying apparatus such as spraying gun. For
spraying the base metal is first prepared to make the surface such
that there is a great adherence of the applied coating on the surface.
The important advantages of the metal spraying are: (a) greater
speed of its working (b) it can be applied to large surfaces and
irregularly shaped articles (c) it is very easy to apply even to
restricted areas (d) coating can be applied even on non-metallic
bases such as glass, wood, plastic etc. (e) sprayed coating has
greater hardness than the cast surfaces of the same metals