Thursday, November 14, 2013

Painting Process and Techniques



The process of painting can be divided into three steps:
a) Pre-painting work
b) Surface preparation
c) Painting

Interior Walls

Pre-painting

Check surface for incidence of dampness or water seepage.
Rectify the water seepage problem at source. This could mean repairing leaking pipes or cracks in the exterior walls.
Any loose plaster should be removed from the wall. Check for loose plaster by tapping on the walls. A hollow sound indicates loose plaster.
Masonry work is to be undertaken to fill up all cracks and repair broken plaster
Please ensure proper curing time (7 to 21 days depending on extent of plastering). When re-plastering is done it should be given proper drying and stabilising time to bridge the cracks or smoothen the surface.

Surface Preparation

Allow newly plastered surfaces to mature for a period of at least 6 months after the application of a coat of lime ash to ensure thorough drying of plaster. Popping of plaster, commonly associated with new Neeru plasters, can be taken care of subsequently during painting.
Remove loose particles and paint flakes. Scrape with sandpaper to ensure that the surface is dry and free from dust, dirt or grease.
Previous coatings of lime wash or powder distemper or cement paint must be thoroughly scraped off. Earlier coatings of oil or synthetic emulsion paints, if in good condition, need not be removed. However, the gloss or sheen of such coating must be removed by thorough sanding.
Cracked or flaked paint must also be completely removed.
Fungus affected areas need to be given a separate treatment. Make a 5-10% 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.

Painting

Apply a coat of wall primer. Use Decoprime Wall Primer (solvent thinnable) on absorbent surfaces and use Decoprime Wall Primer (water thinnable) on new surfaces.
Fill and level the minor undulations of wall by applying putty. In case of major undulations on the wall surface, POP (Plaster of Paris) work needs to be carried out. Ensure that the surface is uniformly smooth by sanding after POP or putty work.
One liberal coat of Decoprime Wall Primer (solvent thinned or water thinned) is recommended on puttied areas before the application of top coat. The primer should be allowed to dry for 10 - 12 hours. If the primer coat is not applied over the puttied areas, there can be a patchy appearance of the top coat.
Avoid application of putty or filling compound while painting exterior surfaces. Fill up cracks with a 1:3 (by volume) cement and sand mixture.
All external drainage pipes must be checked for rusting or leakage. Any faulty plumbing must be rectified
Special attention must be given to the roof. Check for cracks near the edges and close to the water reservoirs. Proper masonry or waterproofing work on the ceiling will enhance the performance of the paint.


Exterior Walls

Pre-painting

For exterior surfaces it is very important to undertake repairs of any wall imperfections before commencing painting. The most common problem with exterior walls, especially old constructions, is cracks in the wall. Avoid applying putty or filling compound while painting exterior surfaces. Fill up cracks with a 1:3 cement and sand mixture. All external drainage pipes must be checked for rusting or leakage. Any faulty plumbing must be rectified.
Special attention must be given to the roof. Check for cracks near the edges and close to the water reservoirs. Proper masonry or waterproofing work on the ceiling will enhance the performance of the painted surfaces.

Surface Preparation

Newly plastered surfaces must be allowed to cure for at least 35 to 45 days before painting.
To ensure long protection, the surface to be painted should be free from dust, grease and any loose materials.
Remove any fungus and algae growth thoroughly by brushing it vigorously with wire brush and then cleaning it with bleaching powder solution in water (dissolve 10% bleaching powder in 1 litre of water, filter the solution and apply with a brush or sponge). This treatment should be done with greater care on the top of the awnings, sunshades, parapets and other horizontal surfaces where water is likely to accumulate during monsoon.
Previously oil painted surfaces should be sanded thoroughly to remove loose particles and made dull and matte for better adhesion. Exterior rough surfaces, previously coated with cement paint, should be wire brushed and washed with water thoroughly and dried completely. Before painting, ensure that the surface is free from chalking.
The exterior surface should not be affected by water and constant dampness should be avoided. If you are painting during the rains, allow for 2-3 days of total sunshine for the surface to dry out completely and before commencing painting.

Painting

Apply a liberal coat of Asian Paints Exterior Wall Primer using recommended method.
Apply two coats of top coat paint at recommended dilution.
A gap of 4 to 6 hours must be given between two coats.
It is recommended that horizontal surfaces like the tops of awnings and parapets must be given an additional coat for greater protection.


Metal Surfaces

Pre-painting

Surface should be free from dirt, dust, grease, rust, moisture etc. The area which is not to be painted must be covered by a masking tape, paper and/or cloth.

Surface Preparation

De-grease and de-rust ferrous metal substrates by suitable treatment.
For nonferrous metal substrates like aluminium as well as galvanised iron, tin, etc, pre-treat the surface with Apconyl Wash Primer - WP 636. For ferrous metal substrates, apply Metal Primer - Corrosion Resistant either by brushing or spraying.
If necessary, the use of Knifing Paste Filler is recommended to fill up dents and rectify surface imperfections.
Ensure that the surface is free from moisture and loose matter.
Apply one more coat of Metal Primer- Corrosion Resistant by brushing or spraying to cover puttied areas.
For best results, allow the primer coat to dry for 6 hours and dry sand with emery paper no. 320 before application of subsequent coat.

Painting

For best results
Allow the surface to dry overnight after application of primer as above.
Apply top coat (Apcolite Premium Gloss Enamel or Apcolite Premium Satin Enamel, Gattu Synthetic Enamel) using the recommended thinner. For best results, apply two coats allowing 8 hours of drying time between two coats.
The first coat should be wet sanded with waterproof emery paper grade 400 before applying the second coat.


Wooden Surfaces

Wooden Surface - Opaque Finishes 

Surface Preparation

Previously painted wooden surfaces must be properly sanded to remove any dust or grease.
Apply wood primer by brush after thinning to given ratio by recommended thinner.
Allow it to dry for 6-8 hours, then apply putty or lambi.
Sand the applied putty with 180 no. sand paper and apply 2nd coat of wood primer.
Now the wooden surface is ready for painting with the top coat

Painting

For opaque finish, you can choose conventional enamels (Apcolite Premium Gloss Enamel, Apcolite Premium Satin Enamel or Gattu Synthetic Enamel).
Apply wood primer by brush after thinning it to a given ratio with the recommended thinner.
Allow it to dry for 6-8 hours then apply putty or Lambi.
Sand the applied putty with 180 no. sand paper and apply second coat of wood primer.
Now the wooden surface is ready for painting with the top coat
Enamels are normally applied by brushing, although they can also be sprayed.
The drying time of enamels is longer; hence care must be taken to ensure a dust free environment while the paint film is drying.
Two coats of paint is sufficient in most cases, however if the earlier paint shade was significantly darker than the new shade an additional coat of paint is recommended.

Wooden Surface - Transparent Finishes 

Surface Preparation

The Wooden Surface to be coated/painted must be seasoned (moisture level between 10-15%). It indicates proper level of moisture and treatment to prevent deformation in extreme hot/cold climate.
In case of new wood surface, first the surface has to be sanded with emery paper along the direction of the grains of the wood to remove the roughness of the wood.
This has to be followed by application of suitable wood filler. The purpose of the filler is to fill the grains and pores and it should not be used as putty. The excess filler must be removed by strokes along the grain pattern. After 30 minutes, the filler may be applied again if required. Allow 2 to 3 hours drying time.
Sand the filled surface with emery paper no. 320.
Staining with Apcolite Wood Stains is optional. Do not use Apcolite Wood Stains on exterior wooden surfaces.

Painting

For New Wood

Ensure that the surface to be coated is free from dust.
Choose any transparent coating from Asian Paints like Touchwood, Melamyne or PU Clear Finish.
Two to three coats of finish coating application are recommended to achieve the best results in terms of gloss and decorative appeal.
Containers should be tightly closed after use.

For Pre-Polished Wood

Sand the surface along the grains with emery paper No. 180 followed by No. 320 to get a smooth uniform surface.
If staining is desired, completely remove the old finish. Wipe the surface free of loose dust.
Proceed with the finish paint coats as explained above.

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