Working with a manual knife grinder provides the opportunity for other kinds of grinding. A sharpening steel or sharpening stones can be used according to taste and what one is accustomed to.
The rough grind is effected on the coarser side of the sharpening stone. The blade is drawn evenly over the stone, in small circular motions, alternating between one side and the other.
Then the stone is turned round and the cutting edge is smoothed on the fine side. The angle used with a sharpening stone is also 20°.

via Giesser Messer