Utilizing an abrasive media, also known as sandblasting or shot blasting, is the most effective method for removing mill scale and rust from surfaces.
This approach involves the mechanical cleaning of a steel surface by the continuous impact of abrasive particles moving at high velocity. Air or water jet streams are the most popular conveyances for this. Therefore, the surface roughness requirement should be described in the surface treatment specification. Typically, this indicates the average profile produced by the blast cleaning procedure.
After the surface has been prepared to an acceptable level of cleanliness and profile, it is essential that the steelwork does not deteriorate. In a moist, humid environment, re-rusting can develop rapidly (known as gingering). If the steel is not stored in a dry environment, the substrate should be coated as soon as possible. Considered a pollutant, any re-rusting of the surface must be eliminated by re-blasting. Prior to painting, galvanized surfaces require more extensive surface preparation than steel surfaces. Failure to properly prepare a galvanized surface will reduce the lifespan of both the paint and the galvanizing beneath it. The most critical component is removing any oil, grease, and other foreign substances from the surface.