Paints form an integral part of any building construction. Not only do they reflect the aesthetic sense of the inhabitants, they also attribute the powers of protection and durability to the walls hiding behind them. Without getting into the science of painting technology, let us approach house painting with a common man's perspective.
It is suffice to know that paints are broadly classified into two categories: water based and oil based. We shall deal with the types of paints, their classification and proper application procedures. The entire painting process can be divided into three stages: pre-painting stage; surface preparation; and paint application.
Interior wall painting
Selection of a painting scheme either as an interior décor or as an external facade depends upon the spaces you are dealing with. Each space has its own requirement and a function. There are four categories of interior wall paints: Distemper regular, Distemper acrylic, Emulsion regular or matt, and Emulsion silk. These are in the ascending order of price and quality. One can choose depending on the affordability factor.
Emulsion paints dry quickly and are washable, stain resistant and durable. They give smoother finish. Distempers are available in dry and oil-bound varieties. They are more popular for lower budget schemes. Oil paints take longer time to dry. Wooden and other metal surfaces are not treated with wall paints. Normally these are treated with Enamel paints. Polishing of wooden surfaces and high-end metallic finishes are not dealt with in this article.
Stage 1
Before starting the painting work, do the following:
Check surface for ingress of dampness or water, including seepage.
Arrest the water problem.
Properly pack gaps between walls and beam joints.
Ensure proper curing of masonry walls before taking up the plastering work.
Ensure proper curing of plastered surface.
Use water-proofing admixture while plastering of walls falling under high moisture zone.
Remove loose patch of plaster if any and re-plaster with care. Plastering layer after drying should not sound hollow when tapped.
Ensure walls are fully dry before taking up any painting work.
Stage 2
Ensure surface is dry and ready to receive the treatment.
In some parts of India, lime rendering is used as a part of internal plastering. Good quality lime must be used. Thick lime layer will lead to flaking of paint and hence to be avoided.
Brush the surface and remove all loose particles.
Sandpaper the surface to ensure that the surface is dry and free from dust, dirt or grease.
In case of repainting, the previous coatings must be thoroughly scraped off.
Fill the cracks using suitable crack filler.
Fungus-affected areas need to be given a separate treatment. Make a 5-10 per cent solution of bleach powder in water and apply on affected areas with brush or sponge. Wash the walls with clean water after an interval of 8-10 hours. Allow the surface to dry sufficiently.
Stage 3
Select proper type of wall primer compatible with the type of paint you chose. This is normally mentioned by the manufacturer. Repeat the process if required.
Apply proper putty and level the surface for undulations. White cement-based wall putty is preferred to Plaster of Paris (PoP) putty. PoP is highly hygroscopic and reacts with water.
In case of major undulations on the wall surface, PoP can be used and then the above procedure adopted.
Allow the primer layer to dry at least for 10 to 12 hours. If the primer coating after drying does not appear uniform, an additional coating is recommended.
Use second layer of putty after primer if the surface is not found uniform and repeat the primer layer as above.
Allow the wall surface to completely dry, then clean and apply two or three coats of the paint that you have selected. Ensure the surface is dry between two coats of paint.
To be continued next week
(The author is Secretary General, ACCE-I)
