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 white metal blast cleaning. Near-white metal blast cleaning@ commercial blast cleaning@ industrial blast cleaning and brush-off blast cleaning are addressed in separate standards. White metal blast cleaning provides a greater degree of cleaning than near-white blast cleaning (SSPC-SP 10/NACE No. 2). The difference between a white metal blast and a near-white blast is that a white metal blast removes all of the coating@ mill scale@ rust@ oxides@ corrosion products@ and other foreign matter from the surface. Near-white blasting allows light shadows@ slight streaks@ or minor discolorations caused by stains of rust@ stains of mill scale@ or stains of previously applied coating to remain on no more than 5 percent of each unit area of surface. 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).