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Different paints are used for different purposes. The most commonly used paints are given below.
Aluminium Paint
Very finely ground aluminium is suspended in either quick drying spirit varnish or slow-drying oil varnish as per requirement. The spirit or oil evaporates and a thin metallic film of aluminium is formed on the surface.
Advantages of aluminium paint are
- It is visible in darkness.
- It resists heat to a certain degree.
- Surfaces of iron and steel are better protected from corrosion by this paint than any other paint.
- It possesses a high covering capacity. A litre of paint can cover an area of about 200 m 2.
- It gives good appearance to the surface.
- It is impervious to moisture.
- It possesses high electrical resistance.
The aluminium paint is widely used for painting gas tanks, hot water pipes, marine piers, oil storage tanks, radiators, etc.
Anticorrosive paint
This paint essentially consists of oil and a strong drier. A pigment such as chromium oxide, lead, red lead or zinc chrome is taken and after mixing it with some quantity of very fine sand, it is added to the paint. Advantages of an anticorrosive paint are
- It is cheap.
- It lasts for a long duration.
- Appearance of the paint is black.
Asbestos paint
This is a peculiar type of paint and it is applied on the surfaces which are exposed to acidic gases and steam.
Bituminous paint
This paint is prepared by dissolving asphalt or mineral pitches or vegetable bitumen in any type of oil or petroleum. The paint presents a black appearance and it is used for painting ironwork under water.
Cellulose paint
This paint is prepared from nitro-cotton, celluloid sheets, photographic films, etc. An ordinary paint hardens by oxidation. Cellulose paint hardens by evaporation of thinning agent. It thus hardens quickly. It is a little more costly, but it presents a flexible, hard and smooth surface. Also, the surface painted with cellulose paint can be washed and easily cleaned. The cellulose paint is not affected by contact with hot water and the surface can stand extreme degrees of cold and heat.
Cement paint
This paint consists of white cement, pigment , accelerator and other additives. It is available in dry powder form. Cement paint is available in variety of shades and it exhibits excellent decorative appearance. It is water-proof and durable. It proves to be useful for surfaces which are damp at the time of painting or are likely to become damp after painting. For external finish, on cement-plastered walls, it is mixed with water immediately before its application. It is desirable to provide cement paint on rough surface rather than on smooth surface because its adhesion power is poor on smoothly finished surface.
For painting surfaces like corrugated iron sheets, etc. cement paint is mixed with boiled linseed oil. The mixture is constantly stirred during use.
Colloidal paint
No inert material is mixed in this type of paint. It requires more time to settle and in the process of settlement, it penetrates through the surface. It may be used for interior as well as exterior walls.
Emulsion paint
A variety of emulsion paint are available. It contains binding materials such as polyvinyl acetate, synthetic resins, etc. This paint is easy to apply and it dries quickly in about 1 to 2 hours. The colour of the paint is retained for a long period. The surface of paint is tough and it can be cleaned by washing with water. There is absence of odour and the paint possesses excellent alkali resistance.
The application of emulsion paint can be carried out either by brush or spray gun. For long service life, it is recommended to apply two coats of emulsion paint. For rough cement plastered surface a thin coat of cement paint may first be applied to smoothen the surface. It is necessary to have a sound surface to receive the emulsion paint.
Enamel paint
This paint is available in different colours. It contains white lead or zinc white, oil, petroleum spirit and resinous matter. It dries slowly and forms a hard and durable surface. The surface provided with this paint is not affected by acids, alkalies, fumes of gas, hot and cold water, steam etc. It can be used for both internal and external walls.
In order to improve the appearance, it is desirable to apply a coat of titanium white in pale linseed oil before the coat of enamel paint.
Graphite paint
The paint presents a black colour and it is applied on iron surfaces which come in contact with ammonia, chlorine, sulphur gases, etc. It is also used in mines and underground railways.
Inodorous paint
No turpentine is used in this paint. But white lead or zinc white is mixed with methylated spirit. White lead or zinc white is well ground in oil. Shellac with some quantity of linseed oil and castor oil is dissolved in methylated spirit. The paint is not durable, but it dries quickly. The methylated spirit evaporates and a film of shellac remains on the surface.
Luminous paint
This paint contains calcium sulphide with varnish. The surface on which luminous paint is applied shines like radium dials of watches after the source of light has been cut off. The paint should be applied on surfaces which are free from corrosion or any other lead paint.
Oil paint
This is the ordinary paint and it is generally applied in three coats of varying composition. They are respectively termed as primes, undercoats and finishing coats. This paint is cheap and easy to apply and it possesses good opacity and low gloss.
It should be remembered that oil paint should not be applied during humid and damp weather. The presence of dampness on wall surface also considerably affects the life of oil paint coating. It is advisable to redecorate the surfaces finished with oil paint with a coating of fresh oil paint only. The layer of old oil paint serves as foundation for fresh paint.
Plastic paint
This paint contains the necessary variety of plastics and it is available in the market under different trade names. The application of plastic paint can be done either by brush painting or spray painting. This paint possesses pleasing appearance and is attractive in colour. This paint is widely used for showrooms, auditoriums, etc.
Silicate paint
This paint is prepared by mixing calcined and finely ground silica with resinous substances. The paint when dried forms a hard surface and it is durable. It can stand extreme heat and it adheres firmly to brickwork also. It is not affected by alkalies. No chemical action takes place on metals by this paint. Drier used with this paint should be of special silicate drier type.
Silicate paint can be applied directly on brick, plaster or concrete surfaces. These surfaces should be made wet before the paint is applied. Two or three coats of silicate paint are recommended and it is not necessary to have a primary coat. The tool which is used to apply silicate paint should be cleaned immediately with water after use. The surfaces should not be painted with silicate paint in hot weather.
Synthetic rubber paint
The paint is prepared from resins. The main advantages of this paint are
- It offers resistance to water and is not affected by heavy rains.
- It dries quickly.
- A uniform colour is maintained when this paint is applied on the surface.
- It is little affected by weather and sunlight.
- It can be applied on surfaces which may not be completely dry, e.g. fresh concrete.
- It is moderate in cost and covers a sizeable area.
- It is easy to apply on the surface.
- It possesses excellent chemical resisting property.
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