Kimo what you are reffering to is sand embedded in the metal. Standard practice is to DA sand after balasting to remove the sand. I do this on blasted exterior SM .I brush frames and the like with a stiff nylon brush and blow with clean air. The peening effect of the sand has no efect on the paint. (but it will 'grow' the metal. A sand blasted surface is great for paint as long as the sand is gone. Many of the parts I make get a great deal of hammering. It does not relate to paint adhearsion. Ray
