Procedure for Protective, Anticorrosive Treatment:
(1) Surface Preparation:
Degreasing: It is a process by which organic deposits such as oil, grease, metallic soaps and inorganic matters like soil, dirt, shop dust are removed from metal surface.
Descaling: The process of removing scales on the ferrous surface.
De-rusting: If the metal is exposed to atmosphere or water, the oxides of iron are formed on the surface of metal, these oxides are called as rust.
This process of removing the rusting on the surface.
(2) Rinsing: To remove all acids and acid salts, the work is passed through 2 or 3 successive rinse baths.
(3) Phosphate Coating: Phosphate coating is secondary metallic phosphate of iron, zinc or manganese deposited on steel surfaces. They provide a good anchorage to the paint film and prevent rust creep underneath the paint film.
(4) Passivation: After Phosphate coating and rinsing, surfaces are given a final passivation rinse with solution of chromic acid to improve their corrosion resistance.
(5) Sealing: After passivation and drying, the sealant is to be applied within 2 hours during monsoon and 6 hours during winter and summer months.
Example: old/new/accidental vehicle, silencer, vehicle body, doors, etc Painting Procedure:
1) Thoroughly wash the vehicle.
2) Carryout protective and anticorrosive treatment.
3) Spray a thin coat of primer. Allow to dry for 15 min.
4) Apply three full coats of surfacer allowing 10 15 minutes between the coats.
5) Allow it to dry for 1 hour. Then wet flat with P 600 grade paper.
6) Apply stopper (putty) wherever necessary allowing 15 to 20 minutes between the layers.
7) Allow to dry for 1 to 1½ hours. Wet flat stopper with 320 wet paper.
8) Spray surfacer to stopped up areas and flat with P 600 grade paper.
9) Blow off vehicle with air gun and tack off.
10) Spray finishing material, apply one coat and allow it to dry for 15 to 30 minutes.
Then apply second coat.
11) Allow overnight drying. Wet flat with P 800 grade paper and dry with air gun.
12) Spay double header coat.