Finishing processes may be employed to: improve appearance, adhesion or wettability,solderability, corrosion resistance, tarnish resistance, chemical resistance, wear resistance, hardness, modify electrical conductivity, remove burrs and other surface flaws, and control the surface friction. In limited cases some of these techniques can be used to restore original dimensions to salvage or repair an item. An unfinished surface is often called mill finish.
Surface finishing processes can be categorized by how they affect the workpiece:
Removing or reshaping finishing
Adding or altering finishing
Mechanical processes may also be categorized together because of similarities the final surface finish.