There are a variety of chemical methods used to remove soils from parts prior to application of a coating. But in many situations the use of chemicals is not practical. The part may be very large or the shop where it is coated may be too small to set up a spray cleaning operation. The part may be contaminated with old paint, rust or mill scale that is difficult or impossible to remove with chemicals. In these situations it is possible to remove the contamination with a blast operation or similar mechanical cleaning. Blasting with a suitable media can remove dirt, mill scale, rust or previous coatings from a substrate, providing a surface profile that gives good coating adhesion.
Blasting alone does not add any pretreatment that will provide extended corrosion resistance to a product. But a thoroughly blasted surface that is free of oils, dirt and other contamination can provide very good results if the coating thickness is adequate and the coating coverage is thorough.