Painting procedure in Building Construction

Wall is being painted

Photo by joshwept

Plastic emulson paint is normally used for painting plastered wall surface inside room. Painting is done in four steps-

Surface preparation
Applying primer
Applying putty
Applying paint

Surface preparation:

Surface should be minimum 45 days old, well cured and completely dry. If there is any defect repair that with cement-sand mortar that is called patch work. Cure and dry the patch work. Apply a coat of lime-wash then allow it to completely dry. Then remove loose mortar, dirt or any other foreign material by applying sand paper on the surface.

Applying primer:

The main job of primer is to provide adhesion between the surface and the paint film. It also make the surface smooth, less absorbent and and increases the spreading ability of paint. Normally primer is applied by brush or roller. Before applying primer it is thinned with water. The coverage area of primer is 45 sqm/gallon.

Applying putty:

Putty is applied to repair cracks and to make smooth & level the surface. After applying putty the surface should be allowed to dry for 4 days. And then scrap off the surplus putty with sand paper.

Preparation of putty: Putty is prepared by mixing 1 gallon plastic paint, 1 litre enamel paint and 25 kg chalk powder with water.

Applying paint:

Paint is applied two or three coat on the surface. After completely drying up the putty the first coat of paint is applied by roller. The paint is thinned by mixing water. The water should be maximum 20% for 1st coat and maximum 15% for subsequent coats. After applying 1st coat surface should be allowed to dry for minimum 7 days before applying 2nd coat. And then 2nd coat of paint is applied on the surface. In this stage, if the surface is not smooth, luster, good opacity and spotless then the 3rd coat should be applied.

Before starting painting work some precautions should be taken.

Precaution: Don't paint during damp, hot and dry weather. Relative humidity should be above 20% and below 50%. Also avoid painting on surface having direct sun contact.