Fixing a Chipped Knife on a 220 Stone

A chip in the edge feels like a disaster. You see a missing piece of steel and think the knife is ruined. It usually isn't. Most chips, even 2 mm deep, can be ground out on a coarse stone. The key is to remove steel evenly along the edge, not just at the chip, so the profile stays the same.

Start with the right stone

Use a 220-grit stone (二百二十番, にひゃくにじゅうばん). This is coarse enough to move steel quickly. Soak it first. A muddy surface cuts faster and more evenly. If you only have a 400, it will work but take longer. Yesterday we used a 400 to thin behind the edge (刃裏, はうら) — today the 220 is for serious repair.

Grind the whole edge, not just the chip

Place the knife on the stone at your usual sharpening angle. Use light pressure and move the blade back and forth along the edge, covering the entire length. Do not focus only on the chipped area. If you grind only the chip, you will create a dip (窪み, くぼみ) in the edge. Instead, work the whole edge until the chip is gone. Check progress often by looking at the edge under light. The chip will slowly shrink.

Reshaping a broken tip

A snapped tip (先折れ, さきおれ) needs a different approach. You must grind the spine (峰, みね) down to meet the edge, recreating the tip. Hold the knife with the tip pointing away from you. Place the spine flat on the stone and grind until the broken area is removed. Then sharpen the edge to meet the new tip. Work slowly and check the shape often. You want a tip that looks natural, not a stub.

Keep the profile intact

The profile (刃線, はせん) is the curve of the edge. After repairing a chip or tip, the profile may change slightly. To keep it, alternate sides and use even strokes. A common mistake is to create a flat spot (平らな部分, たいらなぶぶん) where the chip was. To avoid this, blend the repair into the surrounding edge. After the 220, move to a 400 or 1000 to refine the edge. Finally, sharpen as usual.

Check your work

After grinding, run your fingernail along the edge. It should catch evenly. Look at the knife from the side: the curve should be smooth. If you see a dip or flat spot, go back to the 220 and even it out. This takes time, but it is better than living with a deformed knife.

When to stop

If the chip is deeper than 3 mm, or if the tip is broken far back, you may need to remove a lot of steel. This shortens the knife's life. In that case, consider professional repair. But for most chips, a 220 stone and patience will do. Remember, the goal is not just to remove the chip but to maintain the knife's geometry. That way, it will still cut well after the repair.

Tomorrow, we look at handles: how to remove a burned-in handle and fit a new one. But first, make sure your blade is ready.