The polisher deburrs, smoothes and polishes machined parts using abrasive papers, emery cloths, polishing thread and compounds to produce a smooth surface. He/she then uses specific techniques to achieve the desired finish: satin-brushing to create a mat finish or buffing to produce a high shine. For a particularly high-end finish, black polishing (also called flat polishing) gives a distinctive aspect to certain metal surfaces.
Source: Ordinance of the State Secretariat for Education, Research and Innovation, December 15th 2010