Paint is a fluid material that has the ability to spread on a solid surface. This material on drying will form a film. The paint is applied in different layers over the surface called as the primary coat called as a first coat, second, second loaf etc.
Paints Used in Construction
Painting is the nation's number-one home-improvement project. Paints help to the look of a room from dull to brand new. A proper knowledge of different paints and their applications will help to undergo the project economically and as desired by the user.
Need For Painting in Construction
Painting is necessary for the following reasons:
- Painting will protect the surface from adverse impact of atmospheric action
- The surface is kept clean and safe
- An attractive appearance is given to the surface
Characteristics of an Ideal Paint
A good paint must have the following properties:
- An ideal paint must be easy and freely applied
- A good paint must dry in reasonable period of time
- A good paint must form a hard and durable coat
- The paint should not bring any change in properties with the changing conditions of atmosphere
- The paint should form a thin film without cracking
- The paint should have good spreading power
- The users must not have any health problems from the use of paints
- The paint used must be inexpensive
Different Types of Paints Used in Construction
The different types of paints used in construction are:
1. Oil Paints
2. Enamel Paint
3. Emulsion Paint
4. Cement Paint
1. Oil Paints
|Fig.1.Oil Painted Interior Wall of A Residential Building|
These paints have the white lead as a base. The oil paints are applied in three coats. The first coat is called as a primer, then comes the undercoat and last coat form the finished coat. Before the application of the same, linseed oil and pigments are added.
Oil paints can be of two types: mat and glossy finish. If the surface of application is smooth a glossy finish is recommended. If the surface has undulations that cannot be covered by putty, it is advised to use mat finish. The use glossy finish will make these undulations to be seen evidently.
The oil paints are more durable that it takes time to dry completely. Cleaning of the walls painted by these is easy. Oil-based paints are made with either alkyd (synthetic) or linseed (natural) oils.
|Fig.2.Enamel Painted Interior Wall of a Bedroom|
The enamel paint is prepared by the addition of lead or zinc to varnish. In order to get the required color pigments are added. Before the application of enamel paints, it is necessary to have a titanium coat. These paints can be used for both the interior and exterior walls, metals, and wood.
The enamel paints can be identified by their hard, washable and glossy finish. These are available in both oil-based and alkyd based.
Enamel paints can be used in trims, doors, for different flooring types, porches, and patios, these can also be used in surfaces like wicker, masonry, concrete, plaster, glass, ceramic, metal.
These dry easily and can be easily cleaned. These have good coverage and color retention property.Repetitive washing of the surfaces are allowed by using these paints. These are available is a variety of color range.
3. Emulsion Paint
|Fig.3. Use of Emulsion Paints in Interior Walls|
The binding material used in emulsion paints are Polyvinyl acetate and Polystyrene, pigments and driers. Driers like cobalt and manganese are used widely. This may be an emulsion of water or oil. If it is water based, the emulsifying agents are metallic soaps of zinc or manganese.
Within 15minutes the painted surface will dry. This will get harden within 2 hours. Washing by water will clean the wall painted with emulsion paint.
The emulsion paints are durable and have good color retention property for a longer period. The application of emulsion paint is on interior walls and ceilings. They don;t give a hard surface after drying as in the case of oil paints. There is a special form of emulsion paints that can be used for wood work. When emulsion paint is used for plastering walls, a layer of cement is applied and then painted.
Vinyl silk, vinyl matt, and vinyl satin are three types of emulsion that can be used for wall and ceilings.
|Fig.4.Cement Paint for Rough Exterior Brick Wall|
The cement paint is available in the market as a powder. This will have a white or a colored cement as the base material. Before the application, the powder is mixed with water to the required consistency. These type of cement are best suited for rough surfaces than smooth surfaces.
Cement paints are durable and waterproof. Those surfaces that are more prone to dampness is painted using cement paints. This will have 2 coats of application.
A time period of 24 hours is required for the first coat to dry. The second coat is the final coat that provides a good appearance.
|Fig.5: Bituminous Paint For Metal Sheets|
Manufacture of Bituminous paint is by dissolving asphalt or vegetable bitumen in oil or in petroleum. This paint is black in color and mainly used in ironworks under the water. Under exposure to the sun, the paint will start to deteriorate.
The applications of bituminous paint are waterproofing the concrete foundations, rust resistant surface preparation for metals and cisterns, waterproofing the wooden surfaces, priming substrates before the installation of bituminous membranes.
6. Aluminium Paint
|Fig.6.Aluminium Paint Spraying Metals|
Finely ground aluminium particles in suspension, either in spirit or in oil varnish will form aluminium paint. After the application of aluminium paint over a metal or wood surface, the spirit or the oil varnish will evaporate. After this, a thin metallic film of aluminium is left on the surface painted.
This surface will shine and is even visible during dark. 200metre square is covered by 1 liter of aluminium paint. These are mostly applied for gas tank painting, water pipes, radiators and oil tanks.
7. Anti-Corrosive Paint
This paint is intended to resist the surface against corrosion and chemical attack. This paint consist of linseed oil as the vehicle and the base is zinc chrome. Finely ground sand forms the filler material. The paint is black in color, durable and cheap.
8. Synthetic Rubber Paint
Dissolving chlorinated rubber in the solvent will form this paint. This is an excellent means to resist against chemical attack. It dries up easily. This is less affected by sunlight and varying weather conditions. This can be applied to the surface of the fresh concrete. The cost is moderate.
9. Cellulose Paint
Dissolving nitrocotton, celluloid sheets etc in petroleum will form cellulose paint. The adhesive property of the paint is increased by adding castor oil. The evaporation of the thinning agent in the paint will make the paint to dry and harden. This surface can be washed and cleaned. This is used for painting cars and airplanes.
10. Plastic Paint
The plastic paints consist of a variety of plastics as a base and the water as a thinner. This is available in attractive colours. The composition of 1 litre of plastic paint is 0.20kg of the binder, 0.10kg of solids, 0.50kg of pigments and 0.60kg of water.
After drying, the water will evaporate and will provide an attractive coloured surface. This paint can be used for painting the walls and ceilings of the auditorium, showrooms etc.
11. Asbestos Paint
The fibrous asbestos is present in these paints. This is mainly applied to avoid the leakage of the metal roofs. It can also be used for painting spouts, gutters. Also applied for damp proofing of surfaces in the basement walls.