Knife sharpeners and whetstones
Knife sharpeners and whetstones (or grindstones) are small tools with which - as the designation suggests - knives can be sharpened. Every one of us who works with knives has to sharpen it from time to time as no knife-in-use stays sharp forever. For this purpose a whetstone or grindstone is needed. You can rather cut yourself with a blunt knife than with a sharp knife. Where the sharpness is missing, you have to use more force, which is just the danger. The oldest whetstones found people directly in nature. Today's whetstones, which are used at home, are made of special materials. An example is Carborundum - thermally processed silicon carbide. They are characterized by different shapes (round, oval, triangular or square) and are made in different sizes.
