surface defect marks

General rule is to notice, that specifications of grain is not a reference dimension to RA values.
The specification of grains for a stainless steel surface,means the last touch on the surface of the grain label for shapes etc.

there is no measurable value or conversion factor to specify the grain on a grinded surface !!
Cutting speed connected with various parameters such as diameter from the contactwheeel, length of the abrasive belt,wet or dry sanding and a lot of more reasons finally induce the recognizeable  surface.
Coarse and fine each lies in the perception of personal viewing and the own perception

surface derogations

rolling waves, cooled rollers, adherent scales cause some extreme interference of surface in the raw and polished state.

The polished surfaces exhibit only a previous cut.