Term used to denote, among other things, the finishing of sliding faces performed either by hand with polishing paper on a flat backing or by machine with polishing plates. To obtain a perfectly flat face, preliminary lapping or grinding is essential. In the case of machine polishing it is customary to use diamond powder with carrier medium/lubricant as the polishing agent. The final surface quality (roughness) depends on the grain size of the polishing agent and on the microstructure of the material to be polished. R_a 0.006 mm has been achieved in trials. Polishing the slide faces produces specular surfaces needed to take exact flatness measurements by the interference method (interference). If a seal is installed after a prolonged period in storage, the grip caused by adhesion can lead to startup problems for weak power drives. Where necessary, the mechanical seal manufacturer and the mechanical seal user must agree on higher roughness values.