Steel Surface Treatment Derusting Grade Standard

The most important thing in painting is the quality of material surface treatment, and relevant studies show that the quality of material surface treatment accounts for 40-50% of the factors affecting the quality of coating. The effect of surface treatment in painting can be imagined.

 

Derusting grade: refers to the cleanliness of surface treatment

 

Spray or projectile derusting is denoted by the letter "Sa". There are four derusting grades:

 

Sa1  light spray or projectile derusting

Without magnification, the surface should be free of visible grease and dirt, and free of loose oxide scale, rust and paint coatings.

Sa2 thorough spray or projectile derusting

Without amplification, the surface should be free of visible grease and dirt, and the oxygen should be almost free of scale, rust, coating and foreign impurities, and the residue should be firmly attached.

Sa2.5 is a very thorough spray or projectile derusting

Without magnification, the surface should be free of oil, dirt, oxide scale, rust, coating and foreign impurities, and any residual traces of contaminants should be only slight spots or streaks.

Sa3 steel surface clean spray or projectile derusting

Without amplification, the surface shall be free of visible oil, grease, dirt, oxide scale, rust, coating and foreign impurities, and the surface shall have a uniform metallic color.

Hand and power tools for rust removal

Manual and power tool derusting is denoted by the letter "St". There are two derusting grades:

St2 is thoroughly hand and power tool derusting

Without magnification, the surface should be free of visible oil, grease and dirt, and free of unstable oxide scale, rust, coating and foreign impurities.

St3 is the same as St2, but more thoroughly, the surface should have a metallic luster of the substrate.