TENDENECY OF MATERIAL :-

Like aluminium, galvanized material has tendency to undergo natural corrosion forming a thin layer of zinc oxide or zinc carbonate on the surface which we commonly call as white rust.

NEED OF CLEANING -

PRESENCE OF OIL AND/OR LAYER OF WHITE RUST ON IT’S SURFACE

Galvanized material generally has white rust on the surface. This is not a good base to apply powder or any other coating. Hence, it must be removed before powder coating. Apart from this, there may be oil on the surface which may have come during fabrication process. This must be removed to have proper bonding of powder coating.

NEED OF CONVERSION COATING -

TO PREVENT FURTHER OXIDATION OF CLEANED GALVANIZED SURFACE.

PRECLEANING OF GALAVANIZED SHEETS

This include :

• Alkaline Cleaning & Acidic Cleaning
• Alkaline cleaners :- These are capable of removing only oil. They can not remove white rust.
• Acidic Cleaning :- These are based on phosphoric acid. They are capable of removing white rust in addition to grease and oil.

CONVERSION COATING FOR ALUMINIUM

This include :

• Zinc Phosphate coating
• Chromate coating