Sa1 level
Equivalent to American SSPC-SP7 level. This is the lowest level of the four cleanliness, and the protection of the coating is slightly better than that of the untreated workpiece. Use simple manual brushing and emery cloth polishing methods. The technical standard of Sa1 treatment is that there is no visible grease and dirt on the surface of the workpiece, and there is no weakly attached scale, rust, paint coating and other attachments. Sa1 level is also called manual scrubbing or cleaning level. For industrial coating, Sa1 is not recommended.
Sa2 level
Equivalent to US SSPC-SP6 level. The sandblasting cleaning method is adopted, which is the lowest level in the sandblasting treatment, and the protection of the coating is much better than manual brushing. The technical standard of Sa2 level treatment is that there is no visible greasy dirt, oxide scale, scale, paint, oxide, corrosion and other foreign substances on the surface of the workpiece. Defects are limited to no more than 33% of the surface per square meter, which may include slight shadows; a small amount of slight discoloration, scale and paint defects caused by defects and rust. If the original surface of the workpiece has dents, slight rust and paint will remain at the bottom of the dents. The projectile dents formed after shot blasting are evenly arranged on the steel surface, and the anti-slip coefficient reaches 0.35 to 0.45. Sa2 level is also called commodity cleaning level or industrial level. Sa2 is suitable for steel structural parts used in mildly corrosive environments or occasions where coating design regulations are specified.
Sa2.5 level
It is also called the near-white cleaning level, which is commonly used in the industry and can be used as the level of acceptance technical requirements and standards. Most steel coating configurations require substrate processing to reach this level. The technical standard of Sa2.5 treatment is that when observing without magnification, there should be no visible grease and oil stains on the surface, and there should be no oxide scale, rust, paint coating and foreign matter. Slight stains can be dotted or streaked, but the stains are limited to not more than 5% of the surface per square meter, and may include slight shadows; a small amount of slight discoloration caused by defects and rust; oxide skin and paint defects. The projection dents formed after shot blasting are evenly arranged on the steel surface, and the anti-slip coefficient reaches 0.45 to 0.5. Sa2.5 is a fairly common cleaning level requirement used in industrial coatings, and most of the requirements for high-performance coating design and construction require this level to be selected. Ships, chemical equipment, offshore working platforms, port machinery, wharf facilities, metallurgical machinery, oil production equipment, municipal engineering, aerospace, etc. all require the surface before painting to reach a very thorough cleaning level.