Knife Sharpening

All about Japanese Knife Sharpening

A good Japanese kitchen knife will maintain its sharp edge for a very long time.  Eventually though, like all knives, it will become dull over time and extended usage.   Lack of use over a long period can also cause some carbon steel blades to dull due to corrosion or oxidization of the metal.  Establishing a regular sharpening routine is a good idea.  Professional chefs may sharpen everyday, but at-home chefs can probably get away with sharpening their knives once per month.

Why Sharpen your Knife?

First, a sharp knife cuts better This seems like an obvious statement, but a knife that cuts better /cleaner means quicker, and more enjoyable prep with less wasted effort.  Cleaner cuts also helps protect your ingredients.

Using a blunt knife can damage your ingredients, especially more delicate herbs, vegetables, and fruits (e.g. tomatoes!).  Cleanly cut ingredients will preserve their color and flavor longer, as they sustain less bruising / cell damage around the cut area.

In Japanese cooking, using a sharp blade is especially important.  For many traditional dishes, the appearance is equally as important as taste, and preparation requires intricate, finely cut ingredients.  For example, when preparing sushi / sashimi, using a blunt knife will not only ruin the beautiful appearance of the raw fish, but also the texture and taste.  

Second, a sharp knife is safer.

A dull knife can slip off your ingredients when cutting, as it is not sharp enough to penetrate the surface/skin.  This means the blade can slide into your other hand or fingers.  A dull knife will also cause you to use more force when cutting, which can further result in accidents, and bloody fingers.


How to sharpen your Japanese knife with a whetstone

Using a whetsone is the only recommended way to sharpen your Japanese knife.  For first timers, the task of sharpening your own knife can be daunting, but the process is actually quite straight forward.  As with everything though, practice makes perfect.

If you are not comfortable trying on your own, you can try to find a local sharpening class.  Many manufacturers also offer sharpening services (for a price), so you can avoid doing it yourself altogether.  But, what’s the fun in that??

Here is a basic Japanese knife sharpening guide for Western style Japanese knives (i.e. double bevel).  Different knife types require slightly different techniques due to blade shape, bevel angles, etc., but the basic principles are the same.

Japanese Knife Sharpening Guide – Step by Step

1. Prepare your equipment

Your knife, a towel, bucket/container of water to soak your whetstone, and appropriate whetstone.

Which whetstone should you use?

Whetstones come in various grit sizes depending on purpose.  Low grit stones (120~400) are for rough sharpening, removing chips, and fixing damaged or extremely dull blades.  Medium grit stones (700-2000) are for normal sharpening.  High grit stones (3000+) are for removing scratches, and finishing/polishing the blade.  For beginners like myself, a low grit stone is probably unnecessary, so a medium/high grit stone combo should be enough to start with.   

2. Prepare your whetstone

Soak it in water according to the supplier’s instructions, usually around 10-20 minutes. When no more bubbles appear in the water, the stone is ready for use.   Some stones (e.g. ceramic) do not need to be soaked in water, while others just need a spray of water, so please read your manufacturer’s instructions first.

3. Place your whetstone on a flat surface

You can lay a damp towel flat under the stone to keep it from slipping.   Some stones come with special non-slip base to use when sharpening.  The whetstone should be placed so that the short side is facing your body.Also make sure that the top surface of your stone is completely flat, as stones can become cratered/indented after extended use.  You may need to use a whetstone flattener / fixer to make it level again.

4. Prepare to sharpen the right side of the blade

Hold your knife with your right hand, wrapping your bottom three fingers round the handle, then place your thumb on the flat surface of the knife, and your index finger on the spine.  The knife should be held at approximately at 45 degree angle to the stone with the sharp edge facing your body.  The left hand will be used to press the cutting edge against the stone.  The part of the edge being pressed by your left hand is the part that will be sharpened.

5. Finding the correct bevel sharpening angle.  

To find the correct sharpening angle for your knife, first place the blade flat on the stone.  Lift the spine slowly until you feel the bevel is laying flat against the stone.  Hold that angle, and try to slide the blade across the whetstone.  If it slides too easily, then the angle is not high enough.  If it is catching too much, then the angle is too high.  You need to experiment a little to find the right angle.  Some people like to place a couple of pennies or other object to mark how how high to lift the spine up.  Two pennies is approximately 15 degrees, but your knife may have different bevel angles.  The most important thing is to keep the same angle as you sharpen.  Some knives may not have a symmetrical bevel angle on right and left side of the knife.

6. Sharpen the right side of the blade 

Once you have found the correct angle, use two or three fingers from your left hand to push the cutting edge into the stone.  Then, push the knife straight forward and back along the entire length of the stone while maintaining the same angle.  Apply slight pressure with your left hand as you push forward, and release pressure slightly as you pull back.  Again, the most important thing is to maintain the same angle as you move back and forth.  If it is your first time, you may want to check the blade every few strokes to see your progress.

Focus on sharpening one section of the knife at a time.  Sharpen until you feel a burr develop along the edge.  It may take awhile depending on how hard your knife’s steel is.  Then move on to the next portion.  Repeat until the entire edge of the knife is sharpened from tip to heel.

knife edge

As you sharpen, the water on the stone will start to turn murky / black.  Don’t try to remove the black water, as it actually helps to sharpen the blade smoothly.    If the stone starts to become dry, simply add water onto it.

7. Sharpen the left side of the blade.   

Flip the blade over so that the cutting edge is facing away from you, and repeat the sharpening process.  Your right hand position will be a bit different, with your index finger on the face of the knife, and thumb on the spine.   To sharpen the section closest to the handle, it may help to rotate the knife perpendicular to the stone , so that the handle is not in the way.  Sharpening the left side will also remove the burr created from sharpening the right side.  If your knife’s bevel is non-symmetrical, you may need to find the correct sharpening angle again.

8. Remove burrs, and test knife sharpness.  

Remove burrs by VERY lightly sliding the entire edge of the knife across the whetstone.  Another option is to slide it gently back and forth across a stack of newspaper to ensure it is smooth.  You can also try cutting through a roll of newspaper or sliding the edge across a cork.

Removal of burrs is necessary to ensure you have a clean edge which can make clean cuts through your ingredients.  After removing burrs, test the new sharpness of your knife but slicing a piece of paper.

9. Repeat process with higher grit whetstone (if necessary)

Use a higher grit to finish/polish the blade.  This will give your knife a nice shine, and also help remove any remaining burrs.

10. Wash, dry knife and whetstone

Hand wash and dry your newly sharpened blade.  Rinse, wipe off the whetstone, then store it somewhere away from sunlight.  You are FINISHED!



In this article, we have gone over some general maintenance tips for Japanese knives (washing, usage, storage). We also learned why it’s important to keep a sharp blade, and laid out a basic step-by-step Japanese knife sharpening guide for double beveled blades.

We have covered the essentials for now, but there is still much more to learn!  Sharpening traditional Japanese knives (i.e.  single bevel) requires a different technique due to the more complicated bevel shape.  Also, the many Japanese different knife types, require slightly different sharpening techniques.  Hopefully, we can learn about this in the near future!