THERE IS NO SUCH THING AS A FOREVER SHARP KNIFE. EVERY SINGLE CUT MADE WEARS THE EDGE
Whetstones are the best way to grind, sharpen and hone an edge. This is the method used by the factory or workshop where the knife was originally made. The Japanese generally only use stones used with water rather than oil for working on knives – this gives a less aggressive cutting performance than an oil stone which cuts steel much faster is more for tools such as chisels, plane blades and garden tools.
Stones come in a variety of grades, from rough (low number of grits) to ultra-fine (high number of grits). The grits themselves also have different shapes - nipple nodule, cone shape and shard shape – varying in performance in that order. These grits are all man made (silicon carbide or aluminium carbide) and then used to create a stone using clay or ceramic as a bonding agent to create a ‘brick’.
Like sandpaper, rough stones with < 240 grit cut the steel very quickly but leave a rough edge and are suitable for repairing fine knives or creating an edge on a hard to sharpen knife, 240 to 600 grit stones are used for creating an edge on a fine but neglected knife or for routine maintenance every few months. Medium stones (between 1000 & 1500 grits) are the most suitable grade for regular maintenance and a Fine stones >2000 grit is for varying levels of polishing on fine edges.
As the stone's surface needs to be flat, the ideal purchase of a stone should be with a stone flattener. The lower the grit the faster the stone will wear, but all stones will wear so this maintenance is vital to get the most value and efficiency from your stone.