The galvanized layer has a good protective effect on steel due to the cathodic protection of zinc. There has been rapid development in the field of anti-corrosion in our country, and it has been used in many anti-corrosion projects. However, in marine or industrial environments, the galvanized layer is consumed by about 8 μ m per year, and its durability is always limited. The method of using a combination of galvanized layer and coating for protection is a more proactive and effective way to prevent corrosion.
  After being exposed to sunlight in the atmospheric environment, the galvanized layer will form zinc salts (also known as white rust) on the surface, which must be thoroughly removed before painting. The most effective treatment method is the light sweeping sandblasting method; If sandblasting is not possible, steel wire brushes or steel wool and sufficient fresh water can be used to remove zinc salts through mechanical cleaning and rinsing. The surface of galvanized steel or galvanized iron sheet (also known as self iron sheet) that has not been exposed to sunlight often has oil stains or rust proof oil. It is necessary to remove these oil stains with solvents or detergents before using the above surface treatment methods. It should be emphasized that the durability of paint coatings applied on surfaces treated with wire brushes is much worse than coatings applied on surfaces treated with sandblasting.
  The galvanized layer on steel forms an alkaline surface during cathodic protection. Therefore, the paint matching system used on galvanized steel in flooded or humid environments must have good alkali resistance and cannot be saponified. Therefore, it is advisable to use epoxy coatings. For galvanized steel exposed to dry atmospheric environments, phenolic or alkyd paint matching systems can be used, but the effect is not as good as epoxy.

Note: 1 Firstly, remove oil stains with solvents or detergents, and then use light sandblasting to remove zinc salts (also known as white rust) and make the surface slightly rough.
   2. First, use solvents or cleaning agents to remove oil stains, then use a wire brush and sufficient fresh water to mechanically clean and rinse off zinc salts. After the surface is dry, apply the coating.
   3. After the previous coat of paint is dry, remove the surface oil and dust before applying the next coat of paint. When applying epoxy paint, it is necessary to follow the painting interval specified in the manual.