The purpose of abrasive and/or abrasive injected water blasting on concrete is to produce an even finished appearance or an esthetically pleasing texture on gap graded and architectural aggregate mix concrete surfaces. MPI standards for decorative architectural blast finishes are:· SFI (Brush) - removes surface dirt and stains to give the surface a uniform appearance.· SF2 (Light) - exposes some of the fine aggregate as well as removing surface dirt and stains. Depth of cut shall not exceed 1/16" (1.5 mm).· SF3 (Medium) - exposes the top faces of the coarse aggregate faces near the surface. Depth of cut shall not exceed 3/16" (5 mm).· SF4 (Heavy) - exposes more of the coarse aggregate particles near the surface. Depth of cut shall not exceed 3/8" (10 mm).