Polishing stones refine an edge that has already been cut. They are the step between a file and a finished ski, and skipping them leaves an edge that feels sharp to a thumbnail but grabs unpredictably on snow.
Vitrified aluminum oxide, in four grits, and the progression is the point:
- 220 (coarse): after filing, to take out file marks
- 320 (medium): general refining
- 400 (fine): pre-finish
- 600 (extra fine): final polish, and the one to carry for maintenance
How far you go depends on the snow. Hard, icy race surfaces reward a finer finish: a polished edge holds where a coarse one chatters. For training on soft snow, stopping at 320 or 400 is usually enough and saves time.
Work through the grits in order. Jumping from a file straight to 600 just polishes over the file marks rather than removing them.
Use them wet. A dry stone loads with metal and burnishes instead of cutting: see Secret Sauce.
For removing material rather than refining, see the cutting stones. All files and stones.
