Why is it that the degree of architectural abrasive blasting always seems to be an 'odds on' bet to be a disputed matter between the designer who 'sees' one degree, and the sandblasting contractor who bid another? Why is it that a "light" architectural blast isn't what was wanted when it was what was bid? Why is it that 'one man's junk is another man's treasure?' Standards clarify the issue, and provide a more level playing field.

The following standards have eliminated a considerable amount of dispute.

Schedule of Abrasive Blast Finishes

CSF-1 Brush: Removes surface dirt and stains to give the surface a uniform appearance.

CSF-2 Light: Exposes some of the fine aggregate as well as removing surface dirt and stains. Depth of cut shall not exceed 1/16" (1.5mm).

CSF-3 Medium: Exposes the top faces of the coarse aggregate faces near the surface. Depth of cut shall not exceed 3/16" (5mm).

CSF-4 Heavy: Exposes more of the coarse aggregate particles near the surface. Depth of cut shall not exceed 3/8" (10mm).

NOTE: Finishes SF-3 and SF-4 are most economically and conveniently obtained when the blasting is done well before the concrete has achieved maximum strength.

(See MPI's Architectural Painting Specification Manual for more information.)