Paints, varnishes and distempers

Paints, varnishes and distempers

1. Paints, Varnishes, and
Distempers
SECTION-D

Shivang Madaan | Building Materials | Roll No: 42

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Paints
• Paint is a solution or suspension of pigment, binder, and mineral solvent
• On drying, it forms an adhering film on the surface on which it is applied.
• Leading paint companies in India are- Asian Paints, Nerolac Paints, Berger
Paints, etc.

TYPES OF PAINTS: -
There are two types of paints: -
• Interior
• Exterior
Interior paints are paints that are applied on walls, metals, and wood The ones
applied on walls are distemper, lustre, enamel, and emulsion. Enamel paints are
also used on metals and wood finishes are used on wooden articles.
Exterior paints include emulsions, textured, and cement paints.

CLASSIFICATION OF PAINTS: -

Classification Basis Types of Paints
Curing Mechanism Baking or air-dry
Solvent for the paint Water/Solvent Based
The function of the system component Primer, sealer, undercoat, finishing
coat
Resin Component Epoxy, Alkyd. Acrylic, Polyurethane

Classification of paints based on the type of base used: -
• Oil Paints- Utilize a drying oil that oxidises and hardens to form a tough
elastic film.
• Alkyd Paints- In this, the binder is a strong resin and hence is very difficult
to damage.
• Latex Paints- It is porous, elastic and hence allows quick moisture escape.

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• Epoxy Paints- These are low viscosity, have excellent abrasion resistance
due to the epoxy resin in them.

Classification of paints based on properties: -
• Rust inhibiting Paints and Primers- Have anti-corrosive properties and
pigments to prevent and reduce corrosion of metal.
• Fire Retardant Paints- Formulated with silicone resin and polyvinyl
chloride to reduce fire spread.
• Heat Resistant Paints- In these, silicone resins are used to withstand high
temperatures.
• Tumescent Coatings- These, when exposed to the heat of a fire, swell to
form a thick insulating layer of inert form
Distempers
Most economical type of painting in India. It constitutes chalk, lime, water, and
colouring agent. It is a water-based paint. Also called whitewash job.
Emulsions
A liquid having fine suspended particles. Commonly known as plastic paint.
Water-based paint. It has excellent durability. Is washable, and provides a rich and
matte finish to interior walls. It is also fungus and mildew resistant.
Enamel Paints
This is a paint that air dries to a hard, glossy finish used for outdoor/hard wear.
The term is used to describe oil-based, latex or water-based paints have adopted
the term as well. Also known as hard-surfaced paint.

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Solvent-Based Paints
Lustre, enamel and oil paints come under this. Cant be pre-mixed with water.
Often produces strong odours. These last long and produce rich and desiring
effects.
Texture Paints
Used to create desired visual effects by the use of brushes, rollers, putty knives,
troubles and other applications. Helps in covering levelled and unlevelled surfaces.
Sometimes, these are tinted before application to give the desired colour.
Cement Paints
Used to give new look to cement-based materials (including concrete mortar).
Adds aesthetics and provides waterproofing while supplementing the role of putty.
Primers
Basecoats applied to a surface to improve adhesion of subsequent coats.
Sealers
Basecoat applied to a surface to reduce the absorption of subsequent coats of paint
bleeding through the finish coat.

Wood Finishes
• Used for wooden surfaces
• Better adhesion to wood and enhance the appeal of wooden texture.
• It constitutes of- Spirit, Lacquers, chalk powder, polishes, burnt sienna, etc.

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Types of Finishes
1. Matte Paint: - Also referred to as suede or velvet finish. This dries to a
minimally reflective finish. Good for walls in a low traffic area.
2. Satin/Pearl: - Less shiny than a semi-gloss finish. Good for furniture,
cabinets, and doors.
3. Eggshell: - Slightly glossy. It is washable. Good for walls in high traffic area.
4. Semi-gloss: - Not as shiny as high-gloss. Good for doors, trim and cabinets.
5. High-gloss: - Very shiny. Shows imperfections. Good for trim and doors in
high traffic areas.
Composition of Paints
Pigment Composition
Lead White Basic Lead Carbonate
Yellow Ochre Hydrated Ferric Oxide
Cadmium Yellow Cadmium Sulphate
Red Ochre Ferric Oxide
Chrome Red Basic Lead Chromate
Prussian Blue Ferric Ferrocyanide
Cobalt Blue Cobalt Aluminate
Zinc Green Zinc Chromate
Amber Clay without Fe and Mg
Burnt Sienna Hydrated Ferric Oxide
Lamp Black Carbon

Characteristics of Good Paint: -
• It should possess good spreading or covering power, as it determines the
cost.
• When applied to the surface, paint should form a thin film of uniform
nature.
• The colour of the paint should withstand the adverse environmental
conditions such as rain, heat, wind, etc. for a long time.
• Paint should have such a consistency that it could be easily applied with a
brush or spraying devices.
• Paint should adhere well to the surface to which it is applied.
• It should have an attractive and pleasing appearance.

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• Its initial cost must be fairly cheap and it must prove economical over the
long run.
• It should have ideal resistance to corrosion and protect the material over
which it is used.
• Paint should be such that it dries in a reasonable time and not very rapidly.
• On drying an ideal paint will not show any signs, such as brush marks,
shrinkage marks, cracks, patches, etc.
Components of Paint
Paint normally comprises of 5 ingredients- base, vehicle, colouring pigment, solvent, and
drier.
1. Base- Fine, solid substance, forms the bulk of the paint, determines its character.
It may consist of white lead, red lead, oxides of zinc, iron and aluminium powder,
etc.
2. Vehicle/Carrier- Liquid substance that keeps all ingredients of paint together.
Most common is linseed oil. Other carriers are poppy oil and nut oil.
3. Pigments- These provide the colour of desired shade to the paint. Some of the
most common pigments and the colour they impart are- White Lead(White),
Carbon Black(Black), Indigo(Blue), Copper Sulphate(Green), etc.
4. Solvent/Thinner- Volatile substance, added to ‘thin’ the paint, evaporates quickly
in atmosphere Turpentine, naphthas are two of the thinners mostly used.
5. Driers- Litharge, Red Lead, Sulphates of manganese are used as driers. These are
added to increase the speed of drying. Effect economy, improve durability and
prevent shrinkage.
Varnishes
• It is a solution of resin, either in oil, turpentine, or alcohol.
• Dries after applying, leaving a hard, transparent, glossy film of resin over
the surface.
• Has little or no pigment.
• The most important types are- oils; including spar, shellac, and alkyd.
• Its function is to protect the varnished surface from weathering, to brighten
and gloss the surface with a pleasant look, and make the surface smooth
and polished.

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Ingredients of Varnishes
1. Resins- commonly used resins are copal, shellac, mastic, amber, gum, and
lac. Acts as a base and provides body to the varnish. Copal is the best resin.
2. Solvents- A solvent must suit the resins used and act as a vehicle for the
varnish. Helps in spreading over the painting surface. Some popular
solvents are- boiled linseed oil, spirit, turpentine, and wood naphtha.
3. Drier- should only be added in small quantities. Will injure varnish in
excess. Commonly, litharge and lead acetate are used as driers.
Characteristics of a Good Varnish
• It should give a glossy surface.
• Should be durable.
• It should dry rapidly after application.
• It should not develop cracks after drying.
• It is commonly used on wooden surfaces.
• Colour of varnish should not fade away with time.
• It should not hide the natural grain of the inner surface of the timber.
Types of Varnishes
1. Shellac- It is purified lac formed into thin flakes and widely used as a
binder in varnishes, paints, and stains. Lac is secreted by insects. Natural
colour for shellac is orange, though it may appear to be white.
2. Lacquers- It may be clear or pigmented and can be lusterless, semi-gloss,
or glossy. Dry and harden quickly, produce a water-resistant film.
3. Stains- Obtained in four different kinds- oil, water, spirit, and chemical.
The type of stain to be used depends on the purpose.
4. Oil and Water Varnishes-
• Oil Varnish- Made by dissolving hard resins like amber or copal
in linseed oil. Hardest and most durable of all varnishes.
• Turpentine Varnish- Made from soft resins like mastic. These
dry quickly, have light colours and are not durable.
• Spirit Varnish- Also called French polish. Shellac is dissolved in
spirit and the product is applied in a thin layer. Shows the grains
of timber as it is transparent.

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• Water Varnish- Consist of lac dissolved in hot water with borax,
ammonia, potash, or soda used for wallpapers, maps, pictures,
etc.
Difference Between Paints and Varnishes

Paints Varnishes
Contains pigment Does not contain pigment
Resin is not used Resin is used
Produces non-transparent film Produces transparent film
Hides the applied surface Doesn’t hide the surface
It is mechanical dispersion of one or
more pigments
It is a homogeneous dispersion of resin
in oil/thinner or both.

Distempers
These are comparatively cheap decorative applications to the walls and ceilings.
These are water paints but are less durable than oil or emulsion paints. Applied on
brickwork, cement, and lime-plastered surfaces but are more decorative and
durable than whitewash or colour wash.
Composition of Distempers
Distempers are constituted of: -
1. A base such as chalk powder or whiting
2. Water as carrier
3. Glue or casein as a binder
4. Colouring pigments
Types of Distempers
1. Water-bound Distempers- Available in powder and paste form. Mixed
with water about half an hour before use. Also known as soft distemper.

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2. Oil-bound distempers- A type of oil paint in which the drying oil is
treated to mix it with water. Not suitable for damp situations. On drying,
forms a durable and washable surface. These are odourless, easy to apply,
and dry quickly.