The Knife Vault

“Whetstone” is any stone used for sharpening knives. It may be natural or artificial. Artificial stones are usually in a form of silicon carbide or aluminum oxide. Bonded abrasives are harsher and provide the user with quicker (although courser) edge than most natural stones. They are available as double-sided blocks with a coarse grit on one side and a fine grit on the other or triple sided with three grits from course to fine.

Whetstones do not require lubrication with oil or water although it is common that oil or water is used. Lubrication provides some assistance in the cutting action of the stone however its primary importance is to carry away the filings (swarf).
Finer grades of sharpening stones, especially Natural stones, are used with oil (water can also be used). Natural stones are mined around the world and are usually some form of crystallized quartz (chert).

The Japanese were early developers of water stones, stones lubricated with water. They probably discovered a natural deposit of clay and silica hundreds of years ago. The most famous Japanese Wet Stones are mined in an area north of Kyoto Japan. Today they are also manufactured stones of silicate particles embedded in a matrix made of clay and other minerals. The use of water exposes the abrasive for sharpening. They do wear out faster than other types of stone.