Sharpening and Angles

Japanese knives are thinner and harder than Western knives, so they can take a lower angle. But there is no one correct angle for everybody. On this page I explain how the angle changes the edge, how to find the angle your knife already has, the difference between sharpening and thinning, how single bevel knives are different from double bevel knives, and how to remove the burr at the end.

Which angle? It depends on you

Different people need different edges. Some like it very thin and fine, some like a thicker, stronger edge. The rule is simple: the higher the angle, the stronger the edge. The lower the angle, the more delicate the edge. On Japanese double bevel knives most people go for approx. 10-15 degrees per side, but see it as a rough guide, not a rule. The right angle depends on the knife, the steel and how you use it.

Some knives, like Shigefusa, Toyama and Kato, come with a very low edge. They cut beautifully, but some people chip them. If that happens to you, add a small micro bevel at a slightly higher angle. The knife still cuts very well and does not chip so easily.

Other knives, from Sakai and other regions, come with a very big micro bevel so they don’t chip. Many people find it too big and the knife does not feel sharp enough. Then you can sharpen it at a lower angle instead.

Find the angle your knife already has

The best start is the angle the knife came with. Colour the edge bevel with a marker, put the knife on the stone and lift the spine until the bevel lies flat. Make a few light strokes and look. If the marker comes off the whole bevel, you have the angle. If it only comes off at the top, lift the spine a little. If it only comes off at the edge, lower it.

Then keep the spine at the same height for every stroke. From there you can go a little higher for a stronger edge, or a little lower for a finer one.

Right handed bevel

Some double bevel knives come with a right handed bevel: more bevel on one side and less on the other. They need different sharpening. Follow the bevel that is there on each side, and don’t sharpen both sides the same way. Unless you want to change it to your own preference, then you can reshape it over a few sharpenings. If you are not sure how your knife is made, send me a message.

Sharpening and thinning

The diagram shows two different jobs, on both double bevel and single bevel knives. The red lines are sharpening: a small bevel right at the edge. The blue lines are thinning: a much lower angle, higher up on the blade, behind the edge.

Every time you sharpen, the edge moves a little higher up into the blade, where the knife is thicker. After many sharpenings the knife still gets sharp, but it starts to wedge in food like carrots and onions. That is the sign it needs thinning.

Thinning takes more steel off, so start on a coarse stone, like my JNS 220, JNS 400 or JNS 800 Coarse, or a natural Amakusa or Suisa Omura. Then go up the stones again and finish the edge as normal. Full stone setups are in Stones Recommendations.

On clad knives the thinned area will show scratches in the soft iron. A natural stone brings back the kasumi finish, see Kasumi on Hard Jnats and Finger Stones How To.

Single bevel knives

Yanagiba, deba, usuba, kiritsuke and kiridashi are sharpened on one side only. This is where many people make a mistake. The big flat bevel the smith made (kireha) is not the sharpening angle. Look at the diagram: the blue line along that bevel is thinning. If you put the whole bevel flat on the stone every time you sharpen, you thin the knife every time, and it wears down much faster than it needs to.

To sharpen, lift the spine a little, so you only work a small bevel right at the edge (the red line). To thin, put the whole kireha flat on the stone and keep the line at the top of the bevel (shinogi) straight. Then sharpen the small edge bevel again. Thinning is only needed when the edge bevel gets wide and the knife starts to feel thick behind the edge.

The ura (the back) is only for removing the burr. Use a very fine stone, like a hard natural finishing stone, and only a few light strokes, just enough to take the burr off. Never work the ura on a coarse stone.

The exception is an uneven ura, and this is very common on Sakai knives. If the ura does not touch the stone all the way along the edge, you first need to make it straight, so it touches the stone from heel to tip. Your stone must be completely flat for this, see How To Use Guide for flattening. After that the ura is again only for the burr.

Burr removal and the leather strop

When you sharpen one side, you push up a burr on the other side: a very thin wire of steel along the edge. You can feel it with your thumb, sliding it from the spine over the edge (never along the edge). The burr tells you that you have sharpened all the way to the edge. But the knife is only really sharp when the burr is gone.

On the stones you make the burr smaller and smaller: lighter strokes, finer stones, and switching sides more often at the end. Natural stones remove the burr easier than synthetics, which is one of the reasons you get a finer, keener edge on a Japanese natural stone.

The last bit of burr comes off on a leather strop, like my JNS Bench Strop or JNS Kanayama Bench Strop:

• Edge trailing only. Pull the knife away from the edge, spine first. Never push the edge into the leather, it will cut the strop.
• Very light pressure, only the weight of the knife.
• A little higher angle is ok. On the strop you are not really sharpening, you are only removing the burr. So you don’t need to hold the exact edge angle, a slightly higher angle works fine.
• A few strokes each side is enough. On single bevel knives: the edge bevel first, then one or two light strokes flat on the ura.

A strop is also good between sharpenings. When the knife feels a little less sharp, a few strokes on the strop can bring the edge back before you need the stones again.