It is the so-called "three-point paint, seven-point paint", and the most important thing in painting is the quality of the surface treatment of the material. Related research has shown that the quality of the surface treatment of the material in the influencing factors of the coating quality accounts for 40-50% many. The role of surface treatment in painting can be imagined.
Rust removal grade: refers to the cleanliness of the surface treatment
★ National standard GB8923-2011 description of rust removal grade ★
【1】Spray or projectile to remove rust
Derusting by spraying or projecting is represented by the letter "Sa". There are four rust removal levels:
Sa1 Mild spray or projectile rust removal
Without magnification, there should be no visible grease and dirt on the surface, and no weakly attached scales, rust, paint coatings and other attachments.
Sa2 Thorough spray or projectile rust removal
Without magnification, there should be no visible grease and dirt on the surface, and there should be almost no oxide scale, rust, coating and foreign impurities on the surface, and the residue should be firmly attached.
Sa2.5 Very thorough spray or projectile rust removal
Without magnification, there should be no visible grease, dirt, oxide scale, rust, coating and foreign impurities on the surface, and the residual traces of any pollutants should only be small spots or streaks.
Sa3 steel surface appearance clean spray or projectile rust removal
Without magnification, the surface should be free of visible oil, grease, dirt, oxide scale, rust, coating and foreign impurities, and the surface should have a uniform metallic color.
[2] Derusting by hand and power tools
Derusting by hand and power tools is indicated by the letter "St". There are two rust removal levels:
St2 thorough hand and power tool rust removal
Without magnification, there should be no visible oil, grease and dirt on the surface, and no weakly attached scale, rust, coating and foreign impurities.
St3 is the same as St2, but more thorough, and the surface should have the metallic luster of the substrate.
[3] Flame cleaning
Without magnification, there should be no visible oil, grease, dirt, oxide scale, rust, coating and foreign impurities on the surface, and any remaining traces should only be discoloration of the surface.
A comparison table of my country's derusting standards and foreign derusting standards
Note: Sp6 in SSPC is slightly stricter than Sa2.5, Sp2 is manual wire brush rust removal, and Sp3 is power rust removal.
The comparison chart of steel surface corrosion grade and spray rust removal grade is as follows:
