SP6 commercial blasting for clean surfaces removes all rust, paint, dirt, or other coatings and contaminants on the surface of the material. 

Surfaces blasted with SP6 requirement must be at least two-thirds clear of visible residue or previous coatings per square inch. This would leave small amounts of faint spots on the material that are still removed enough for a new coating to be applied after. This is an industry standard blast that will get the job done.