Mechanical polishing covers grinding, polishing, and buffing – all processes for improving the surface conditions of a product for decorative or functional purposes. The various techniques are abrading operations although some plastic working of the surfaces may occur, particularly during buffing.
The process is to do grinding first, polishing second, and buffing third. In general, grinding permits far more aggressive abrading action than polishing. Likewise, polishing is a far more aggressive abrading action than buffing.