①Choose any size you want to sharpen and trim the leather sheet with it

②Rub Polishing compound and a few drops of oil on the trimmed edge of the leather sheet, and

③ put the blade part on the leather and pull off at a fixed angle while polish the blade.

④ You can get the original sharpness of the blade. Repeat the above process (from ① to ③) when the blade becomes dull.