How-to

How to Sharpen Japanese Knives: Methods and Tools

Learn how to sharpen Japanese knives by hand on whetstones, with steps for double-bevel and single-bevel blades, stone prep, and when to sharpen.

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Japanese knives are sharpened by hand on whetstones, and that one fact changes what the upkeep looks like. Before you buy a set, it helps to know that both single-bevel and double-bevel blades ask for stone work, so sharpening is a skill you build rather than a gadget you plug in.

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A small kit covers most sharpening

Hand sharpening needs less equipment than it first appears, but each piece has a clear job. The best japanese knife set under $200 roundup lists the steel and edge specs of each set, which shows how much stone work a given blade is likely to need.

Five steps to prepare the stone and the knife

Preparation takes only a few minutes, but it decides how the stone behaves once the blade meets it. Skip it and the edge will often wander.

  1. Soak the rough and medium stones in water for 10-15 minutes.
  2. Splash fine stones with water as you work rather than soaking them.
  3. Set the stone on a wet cloth or a base so it stays steady.
  4. Hold the knife with your index finger on the spine, thumb on the flat, and three fingers around the handle.
  5. Keep your shoulders square to the stone and your upper body relaxed.

Four steps to sharpen a double-bevel edge

A double-bevel blade, such as a gyuto or santoku, is sharpened on each face along the band that runs from the shinogi line to the edge. Check the bevel before you start, because the front and back do not always carry the same amount of edge, and that changes how many strokes each side needs. Hold the angle steady from the first stroke to the last.

  1. Press the edge to the stone with two or three fingers.
  2. Push forward with pressure and ease off on the return stroke.
  3. Work a little of the edge at a time, close to the stone, until an even burr runs the full length.
  4. Reverse the blade, start at the tip, and press harder on the downstroke to remove the burr.

Single-bevel blades need the shinogi line left alone

Yanagiba, usuba and deba knives have a single bevel, and the shinogi line is what lets the blade glide through food. When you sharpen one, take care not to change or erase that line. Work until a slight, even burr shows on the reverse side, then remove it by pressing the edge gently to the stone while your thumb rests lightly on the spine. Pressing both sides this way keeps the slight concave shape of the reverse side, which makes future sharpening easier.

The paper test tells you when to start

Before you reach for a stone, check the edge. Slice a sheet of paper. If the blade cuts it cleanly without catching, the knife does not need sharpening yet. If the paper crumples or tears under the edge, the blade has dulled or has dull patches that need attention.

Sharpening early is easier than waiting. A blade that has only lost a little sharpness takes less work to bring back than one that has been left until it drags.

Keeping whetstones flat and dry

Stones wear down with use and then stop doing their job, so they need flattening. A stone left concave will change the shape of the blade you sharpen on it, and that is a problem no amount of technique fixes.