Japanese Sharpening Stones

The soft Japanese water stones should only be used with water. They allow for effective sharpening because the loose bonding continuously releases new abrasive particles. It is sufficient to soak them in water for five to ten minutes before sharpening. It is less advisable to leave them in water constantly as a greasy layer can form on the surface, or in some cases, the surface may disintegrate.

However, these stones hollow out faster than hard stones and therefore need to be regularly re-flattened. This can be done quickly with the following method: You will need waterproof sandpaper, grit 80 and finer, a smooth surface to use as a base, preferably a glass plate, and if you want to speed up the process, a can of silicon carbide powder. A puddle of water on the glass plate to hold the sandpaper in place, a bit more water, and a teaspoon of silicon carbide powder on the paper, move the stone over it with little pressure—and within a few minutes, it is perfectly flattened.

As a basic kit, it is recommended to have: a sharpening stone with grit 700 – 1200, a honing stone with grit 3000 – 6000, and a sharpening guide. As a supplement, a coarse stone with grit 120 – 400 is advisable. If plane irons are also to be sharpened with the sharpening guide, the stone should be a few millimeters wider than the widest iron. Sharpening and honing stones are also available as combination stones.