Why Did My Knife Chip or Dull, and How to Fix It

0:00The profile that went the wrong way

A new knife curves up at the tip, and this one curved down. You have probably seen the same thing on a friend's knife, or on your own: the middle of the blade is flat, and the tip has hooked over.

A knife, when it's new, should have a curved up, and this knife is curved down.

1:47Why it happens

The usual cause is sharpening only the part of the blade you actually use. That section dulls first, so it gets sharpened first, and over time it gets sharpened over and over while the rest of the blade is ignored. The profile goes flat, and then the over-sharpened section starts to hook.

7:20The fix

At this point the knife has lost its chef-knife profile, so the fix is a full reprofile: reshape the blade back to a proper curve, then do a major thinning pass to bring the edge down to the cladding line.

So we are cutting the potato, no longer splitting. And this is the combination of reprofiling, thinning, and sharpening.

9:11The moment of truth

The whole job took about forty minutes, most of it thinning. A light refinish on 400 grit cleaned up the scratch pattern, then a fresh edge on 1,000 grit. The result: the potato is cut, not split. That is the combination of reprofiling, thinning, and sharpening.

0:00How do you remove a small chip in a knife edge?

The video starts with a knife with a small chip, about 3 mm by 1.5 mm, ground down on a sandpaper jig with 100 grit sandpaper. Sandpaper is very aggressive, so a new strip goes on as soon as the old one stops cutting.

So as soon as you feel like it's not cutting, just use a new one.

0:49What finishes the edge after the chip is removed?

Six passes of 100 grit sandpaper take the chip out, and a 200 grit strip evens the area before the surface is finished with sandpaper. The edge then goes onto the standard 400, 1000 and 3000 grit sharpening stones, followed by a little strop.

And this is the 200 grit sandpaper. I just use it to make it more even.

0:00Can a slightly bent knife tip be fixed?

The video starts with a knife whose tip has bent a little after delivery. There are two types of bends, a slow hard press and an impact that can break the tip a little, and the two are fixed differently.

There are two types of bent, and we're going to fix it differently.

0:37Can a bent tip be straightened by hand?

The tip is not that brittle, so it can be pressed back straight on a hard surface. That makes the tip straight in most cases, though a tiny bend can remain that straightening alone cannot fix.

Usually what we do is we try to, on the hard surface it's not that brittle. So you can try to straighten it back like this.

1:39What if a bit of the bend will not straighten?

What is left is removed by sanding the tip down with sandpaper. A bit of oil or water helps. The sanding goes from the spine side, because sanding from the tip would damage the profile of the knife.

You're not doing it from the tip because that would damage the profile of the knife.

0:00What happens when a damaged knife comes in for sharpening?

A knife sent in for sharpening is inspected first to identify the problems. This one has a broken tip and a few microchips on the edge.

When a knife comes in for sharpening, we inspect it first and identify the problems.

0:17How are microchips removed on a damaged knife?

The broken tip is fixed first on a big water grinder, taking care to remove all the microchips on the blade. The edge then goes onto stones, from 400 grit all the way up to 8,000 grit, followed by a bit of stropping and a test of the final result.

Our standard progression starts from 400 grit and all the way up to 8,000 grit, followed by a bit of stropping.