How to Sharpen Japanese Woodworking Knives posted on 11:36am by David

This information applies to all single bevel chisels. Because most Japanese woodworking knives are ground with a single bevel, they are relatively easy to sharpen. WARNING: under no circumstances should the blade be ground on an un-lubricated grinder. To do so will destroy the temper of the blade. While oil stones can be used for sharpening Japanese knives, much better results will be obtained using Japanese water lubricated sharpening stones. Generally speaking, Japanese water stones can be divided into two classes: Coarse stones for initial sharpening and Finish stones for final polishing to a razor sharp edge. First, check to be sure the surface of your sharpening stones are flat. Otherwise, it will be difficult, if not impossible, to obtain a well sharpened edge. If you are using Japanese water stones, please follow our instructions for flattening your water stones. Now inspect the edge of the blade for any nicks or other defects. If there are any defects, rub the edge of the blade at a 90° angle on a coarse stone until they are completely removed. While doing this, be careful not to change the profile of the edge. The back of the blade should be sharpened first. To do this, place the blade perpendicular to the length of a coarse stone with finger pressure applied directly on the bevel. Rub the blade back and forth across the stone until the area directly behind the edge is honed the full length of the edge. Be careful not to over-sharpen the back. It is not necessary or desirable to completely fill in the hollowed area. This will be obvious by inspection. Now transfer the blade to a finish stone and hone the back of the blade until a mirror finish is obtained. To complete the sharpening, rub the bevel across a coarse stone until a burr is obtained along the full length of the edge. The presence of a burr is easily felt by drawing a finger at a 90° angle across the back of the edge of the blade. As soon as the burr is detected, transfer the blade to the finish stone and alternately hone the bevel and back side until the burr disappears. Best practice is to hone at a ratio of five strokes on the bevel for each stroke on the back side. Should the edge seem somewhat brittle and not hold up well in hardwoods, it may be necessary to add a "micro bevel". This is done after initial polishing by increasing the angle of the bevel to the finish stone about four to five degrees and honing ten to fifteen strokes. A brittle edge in a new tool is usually considered to be a sign of a superior tool. As the tool is sharpened and the surface metal formed at the time of manufacture is removed, tougher, more durable metal underneath is exposed. Additionally, the honing process itself is thought to increase the edge holding properties of the blade. The tips of Japanese knives are very thin and hard and will occasionally break during use. This is a normal condition, and many Japanese woodworkers regrind the tip even before using the knife. The best way to deal with a broken tip is to turn the knife on its back edge rub at an angle of 60° to 75° on a very coarse stone. Continue in this fashion until the broken portion has been ground away and a sharp point re-established. Carefully dry the blade and apply a light coating of Camellia oil or mineral oil. If you have any questions or problems regarding sharpening, please feel free to contact us. Comments (1)