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How to sharpen a Japanese kitchen knife?

When buying a Japanese kitchen knife, you should also consider the tools for its maintenance. It is these accessories that will make the blade sharper. Few manufacturers take the time to finalise the sharpening of their knives, as this represents a huge loss of earnings. The best way to ensure the efficiency of your knife is to sharpen it yourself. I will show you the steps and tips to follow for a perfect edge.

Sharpen your blade like a pro!

1) Soak the sharpening stone

The sharpening stone is certainly the best choice for taking care of the edge of your knives. The sharpening stone is the most effective tool for sharpening your knives. This « old-fashioned » sharpening method allows you to achieve very high cutting standards.

Choosing the right sharpening stone

There is a wide range of sharpening stones on the market, but they are not all equally effective. The first thing you have to do is to choosing the right stone for your needs. One of the criteria that should guide your choice is the grain of the stone, it determines how fine the sharpening will be. Steel blades could break during sharpening due to their rigidity, the use of grained stones is recommended to avoid this type of scenario. Each stone has a grain that corresponds to a use. For example, the thicker grit is used to make up for a dull blade.

The different types of stones

After selecting the ideal grit, you will have to choose between the different stones available: diamond stones, natural stones and compound materials. The easiest to use when you are a beginner are the recomposed stones. They are made from stone dust. Natural stones are more comfortable to use but should be reserved for professionals.

Moisten the stone

Japanese stones or water stones necessarily need to be immersed in water for a certain period of time before being used. The average immersion time is 5 to 10 minutes. This technique promotes better abrasion. Make sure that the bubbles disappear before removing your stone from the water. If you are careful, you will see a slurry called « Slury » that will appear when the water mixes with the abrasive grains from the stone.

This technique is interesting because the water quickly removes the residue (metal particles that might have scratched the blade) from the sharpening process. Then remove your stone from the water and work on the first side using back and forth movements. Do the same for the other side of the knife.

2) Choosing the right sharpening angle

With new technologies and laser cutting, one might think that all knives are made the same. If you take 5 knives of the same model in your hand, you will see that they are not all similar. The knives are assembled by hand, which means that they are sharpened by hand. In order to sharpen your knives successfully, you must choose the ideal angle. Choose a sharp angle for a sharper blade. Choose a wider angle, for a less sharp blade but one that will keep its edge longer. It is therefore necessary to find the right balance between the knife’s original angle and the performance you wish to achieve.

The sharpening angle of the knife

The sharpening angle of a knife is half the angle of the knife. It is usually 30°. In addition, the sharpening angle of a Japanese knife would be 15°. However, if when using this angle you notice that your knife dulls faster than expected, change your sharpening angle a little by widening it. As a guide, here is some additional information on choosing the right sharpening angle:

  • 46° for heavy-duty knives ;
  • Between 36 and 40° for normal use knives;
  • 30° for light-duty knives.

After choosing the right angle, the next step is to determine the height of the blade during sharpening.

3) Sharpen the blade with an 800 grain stone

Before you start sharpening, you need to be able to determine the right grit size (defines the size and fineness of the stone). The smaller the grain size, the coarser the stone to be sharpened. It is therefore advisable to use a fine stone for precision sharpening. It is the grain of a stone that gives a more or less blunt appearance to your knife. Generally for weak or medium steels that we situate at an HRC of 53, 800 stones are recommended. These grains have the possibility to play 2 specific roles. On the one hand, they can be used to finish low HRC steels and on the other hand, they can be used for the entry into the Rockwell C degrees of one notch higher. Opting for finer or higher grit stones will not do you much good. Indeed, there is no chance that knives in this category will retain their effectiveness for long if you sharpen them with this kind of stone.

4) Sharpening the blade with a 3000 fine grain stone

The 3000 fine grain stone is the perfect accessory for blades with high average Rockwell C grades. These stones will give a real edge and on some models, the blade could become razor sharp. They are therefore quite versatile stones that can polish the surface of the knife. As with the previous stone, there is no need to go higher than 3000 grit with knives of lower HRC. The trick is to sharpen in stages, as there are several double-sided stones. These stones require a certain amount of skill to achieve the desired result. This type of stone is advantageous, as it does not damage the edge even if you do not know how to sharpen. This is the opposite of stones with a lower grain size, where the risk of over-sharpening the steel is high, especially if you are not a professional sharpener.

5) Sharpen the blade with an ultra fine 8000 grit

The 8000 grit is perfect for a HRC of 63. Generally speaking, professional sharpeners use this type of stone. Professional sharpeners prefer this type of grit stone, as it allows for precise and very fine finishes. One of the best methods of checking whether the sharpening is effective is the paper test. It should be taken with a grain of salt, however, as it works very well with high Rockwell C blades, but not so well with weaker blades. If you really want to slice through a sheet of paper without any effort, we recommend an ultra-polished sharpening with 8000 grit.

As you can see, the 8,000 ultra fine grit is well suited for Japanese knives due to their solid steel. However, it is less suitable for European knives, which are considered too soft. It is not uncommon to see users get offended when their western knives cannot cut leaves. It is not your stone that is failing, rest assured. Note that your knife can be sharpened in the rules of the art, without being sharp, the fault of the very high degree of finishing of the stone.

Japanese knives have a stronger steel than European knives. This gives them a specific sharpening process that can be summarised in a few steps. You have to soak your stone in water for about ten minutes, the time it takes for the bubbles to disappear. Then comes the stage of the sharpening angle according to the use you intend to make with your knife. Each type of blade has its own specific grain size. The list of grit stones that we have enumerated is far from exhaustive, but their choice must be made according to the strength of the steel to be sharpened. If you follow all our advice to the letter, you will see that sharpening a Japanese knife is no big deal. Everything will be child’s play.

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What are the best brands of Japanese knives ?
How much does a good knife cost?
What is the Kiritsuke Kotai chef’s knife worth ?
What are the different types of Japanese knives ?
How to choose a Nakiri knife ?