A whetstone is made from silicone dioxide minerals that are mined and separated into soft, medium or hard grade stones with fine, medium and coarse surfaces. To prepare the stone for sharpening, a light weight lubricating oil or a sharpening oil made for Sharpening Stones is added to the stone. This is done in order to stimulate the natural oils within that assist to sharpen a blade as one edge is lightly rotated in a circular motion as it is pressed against the stone. Different grades of stones provide different results for heavier or lighter grade steel blades.
A carborundum stone is an abrasive material made of silicon carbide that sharpens blades and, over time, deteriorates in surface structure as continual sharpening wears down the surface of the carbide material. Rectangular in shape, this stone often has a smooth and a coarse side, referred to as a double-grit or combination stone. The coarse side, made of a harder stone, is used first and then the knife is finished by using the smooth side, which is a softer stone. To sharpen the blade, one side of the blade is drawn straight across the flat surface of the stone. The knife is then turned over to the other side of the blade and the process is repeated. When sharpening in this manner, the coarse side is used first, which enables the blade to be ground into shape fairly quickly. Then the blade is moved against the smooth side resulting in a smoother finish and a sharper edge, eliminating the very tiny rough edges that may be present from the sharpening on the coarse surface.