Sand blasting is
primarily a
pre-treatment process. It is usually carried out to ensure that the
surface of a part is thoroughly cleaned before PTFE coating or the
other conversion processes.
Blast cleaning is done in a suction blast machine using mainly aluminium oxide. Other blast medium can be used also.
A major advantage of this cleaning process for ferrous substrates is that not only are old paint films removed, but also rust and scale, leaving a clean metal surface which is ideal for re-coating.