Foreword This joint standard covers the use of blast cleaning abrasives to achieve a defined degree of cleaning of steel surfaces prior to the application of a protective coating or lining system. This standard is intended for use by coating or lining specifiers@ applicators@ inspectors@ or others whose responsibility it may be to define a standard degree of surface cleanliness. The focus of this standard is commercial blast cleaning. White metal blast cleaning@ near-white blast cleaning@ industrial blast cleaning@ and brush-off blast cleaning are addressed in separate standards. Commercial blast cleaning provides a greater degree of cleaning than industrial blast cleaning (SSPC-SP 14/NACE No. 8)@ but less than near-white blast cleaning (SSPC-SP 10/NACE No. 2). Commercial blast cleaning is used when the objective is to remove all visible oil@ grease@ dust@ dirt@ mill scale@ rust@ coating@ oxides@ corrosion products and other foreign matter@ leaving staining or shadows on no more than 33 percent of each unit area of surface as described in Section 2.2. The difference between a commercial blast and a near-white blast is in the amount of staining permitted to remain on the surface. Commercial blast allows stains or shadows on 33 percent of each unit area of surface. Near-white blast allows staining or shadows on only 5 percent of each unit area. The difference between a commercial blast and an industrial blast is that a commercial blast removes all visible oil@ grease@ dust@ dirt@ mill scale@ rust@ coating@ oxides@ corrosion products and other foreign matter from all surfaces and allows stains to remain on 33 percent of each unit area of surface@ while industrial blast allows defined mill scale@ coating@ and rust to remain on less than 10 percent of the surface and allows defined stains to remain on all surfaces. This joint standard was prepared by the SSPC/NACE Task Group A on Surface Preparation by Abrasive Blast Cleaning. This joint Task Group includes members of both the SSPC Surface Preparation Committee and the NACE Unit Committee T-6G on Surface Preparation (now STG 04).