How to Sharpen a Japanese Knife on a Whetstone — A Sharpener's Guide

Sharpening is the heart of what we do at Japanese Knife Studio. Balazs spent twenty years as a chef before he moved behind the stones full time, and this is the method he uses and teaches in our Brisbane workshop every week. A Japanese knife is made to be sharpened on whetstones. Look after the edge and the knife will cut better in its fifth year than the day you bought it.

What you need

Step 1. Prepare the stone

Most synthetic stones need a soak. Put the stone in water until the bubbles stop, usually five to ten minutes. Splash and go stones, which include many fine stones and diamond plates, just need water on top. Set the stone on your holder or sink bridge so it cannot shift.

Step 2. Find your angle and hold it

For a double bevel Japanese knife, aim for roughly 12 to 15 degrees per side. That is noticeably lower than a Western knife. A practical trick is to rest the blade flat on the stone, then lift the spine about the height of two stacked coins. Lock your wrist. The exact angle you choose matters less than holding it the same through every stroke.

Step 3. Raise a burr on the first side

Place two or three fingers of your free hand on the flat of the blade near the edge, and push the knife along the stone edge first, keeping the angle. Work in sections: tip, middle, heel. A section is done when you can feel a burr, which is a tiny wire of steel that folds over to the other side of the edge. Run your thumb across the blade on the back side, never along it. The burr feels like a faint catch. If there is no burr you have not reached the edge yet. Keep going and resist the urge to press harder.

Step 4. Repeat on the second side

Flip the knife and do the same until the burr flips over to the first side. With practice you will alternate sides in fewer and fewer strokes.

Step 5. Refine and remove the burr

Move to your fine stone and repeat the whole sequence with light pressure. The stone should do the work. Finish with a few very light strokes, edge first, alternating sides, to chase off the last of the burr. A strop will remove any remainder. So will a few careful strokes on newspaper laid flat over the stone.

Step 6. Test it

A properly sharpened knife slices cleanly through a sheet of paper held by one corner, or takes the skin off a tomato without any pressure. If the paper snags at one spot, that section still carries a burr or a dull patch. Go back to the stone for that section only.

Mistakes we see in the workshop

  • Chasing sharpness with pressure. Heavy pressure flexes the edge and rounds it off. Let the abrasive cut.
  • Changing the angle mid stroke. A rocking wrist polishes the shoulder of the bevel and never touches the edge.
  • Sharpening on a dished stone. Flatten every session. It takes thirty seconds.
  • Skipping the burr check. The burr is the only proof you have actually reached the apex. Trust your fingers, not the number of strokes.
  • Using a pull through sharpener on a Japanese knife. They tear the fine edge and can chip hard steel. Please don't.

Single bevel knives are a different discipline

Yanagiba, deba and usuba are sharpened on one side, with a flattened back called uraoshi, and it is much easier to damage the geometry. If you own a single bevel knife and have never sharpened one, bring it to us first. Better still, learn on your own knife in one of our classes.

Rather watch someone do it, or have us do it?

We run hands-on knife sharpening classes in our Brisbane CBD studio where you learn on your own knife. Our professional sharpening service restores edges, repairs chips and thins tired blades, by hand, on whetstones. Everything above applies to a knife in reasonable condition. Chips, broken tips and years of neglect are workshop jobs.

Questions about a specific knife or stone? Email contact@japaneseknifestudio.com.au or drop into the studio at Lot 10, 198 Adelaide Street, Brisbane City.

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