Surface preparation standard grades: What is Sa 2.5 in Shot blasting

    The national standard GB8923-88 “Steel surface preparation standard grades and rust removal grade before painting” classified the rust removal grade of shot blasting machine into four grades, which are represented by the letter “Sa”.

• Sa 1: Mild spray (Sandblasting) or projectile (shot blasting) rust removal. There is no visible grease or dirt on the surface of the steel, and there is no loose oxide scale, rust, paint coating and other attachments.
• Sa 2: thoroughly spray (Sandblasting) or projectile (shot blasting) to remove rust. There should be no visible grease, dirt, oxide scale, rust and other attachments on the steel surface, and the residues should be firmly attached. The projectile dents formed after shot blasting are evenly arranged on the steel surface, and the anti-slip coefficient reaches 0.35～45
• Sa 2^1/2: very thorough spray (Sandblasting) or projectile (shot blasting) to remove rust of Sa 2.5. There should be no visible grease, dirt, oxide scale, rust, paint coating and other attachments on the surface of the steel, and any remaining traces should only be light spots or strips. The projectile dents formed after shot blasting are evenly arranged on the steel surface, and the anti-slip coefficient reaches 0.45～5
• Sa 3: makes the steel surface clean by spray (Sandblasting) or projectile (shot blasting) to remove rust. There should be no visible grease, dirt, oxide scale, rust, paint and other attachments on the steel surface, and the surface should show a uniform metallic luster.