The classification of steel rust

 First: the jet or projectile rust, with Sa expressed.Can be divided into four levels:

 
  (1)Sa1 grade mild sand-blasting the surface should be no visible dirt, grease and attachment is not strong oxide, paint coating layer, rust and other impurities.
  (2)Sa2 grade thoroughly sand-blasting the surface should be no visible oil, dirt, scale, rust, paint coatings and basically remove impurities, should be attached to a solid residue.
  (3)Sa2.5 level very thorough sand-blasting the surface with no visible fat, scale, dirt, paint coatings and impurities, shows only slight traces of residue stains or spots stripe.
  (4) Sa3 grade sand-blasting to clean the surface of the steel surface with no visible oil, dirt, scale, rust, paint coatings and impurities, the surface has a uniform metallic color.

Second: power tools and hand-rust, represented by St divided into two levels:

  (1)St2 thorough hand and power tools rust, the steel surface with no visible grease and dirt, no attachment is not strong oxide, or rust paint coatings and other attachments;
  (2) St3 very thorough hand and power tools rust steel surface should be no visible grease and dirt, and no attachment is not strong rust, scale or paint coatings; and the rust is more than St2 completely, exposed surface portion of the substrate has a metallic luster.