Japanese Knife Sharpening and Maintenance Guide

There is nothing worse than a dull knife.

Or a chipped knife.

Or a rusted knife.

Or…

Well, you get the point.  Once you lay down some big bucks on a beautiful Japanese knife, you’re going to want to take care of it.

Knowing how to correctly maintain and sharpen your blade will not only make it more effective, but will also prolong its useful life and give you many years of loyal service.  

In this guide, I will go over some basic knife maintenance tips, as well as a step by step outline on how to sharpen your Japanese knife.

General Knife Maintenance and Usage

Washing / Drying

You should always hand wash, and hand dry your knife (don’t forget the handle).  Never put it in the dishwasher.   Some entry-level knives will say they are “dishwasher safe”, but I think it is best to get in the habit of hand washing and drying.  Simply use a soft sponge, some dish soap, and hot water.  If you put the knife in a dishwasher, there is also a chance it will rattle around and damage the cutting edge.

Many high-carbon steel knives will rust, or discolor very quickly if left wet, ruining your beautiful knife.  Therefore, it is also smart to have a towel on hand that you can use to quickly wipe off moisture as you prep food.

Usage

Never try to use your Japanese knife to cut through hard bone, or hard surfaces.  Japanese blades are made from very hard steel (60+ HRC) which allows it to retain a sharp edge for a long time, but also makes it more brittle.  They are also much thinner, with a more acute cutting edge than a typical Western-made knife.  This further increases the potential of chipping if used incorrectly.

When talking about steel, “hardness” is very different from “toughness”.  Hardness refers to the ability to withstand penetration, or scratching  (e.g. a diamond is super hard).  Toughness refers to the material’s ability to absorb energy, or withstand a fracture.  As hardness increases, toughness decreases.  For example, Western made knives use softer steel (55~58 HRC) which will dull more quickly than Japanese knives, but are “tougher” and less likely to chip.  Knife makers are constantly trying to find a good balance between the two properties.

 

You also need to be using proper cutting technique.  This means using a smooth cutting motion, and not exerting an excessive amount of force to drive your knife down into the cutting board.  If you find yourself using lot of strength, either your knife is not sharp enough, you are using the wrong type of knife, or you are trying to cut something that you should not be.

Cutting Boards

Your cutting board should not be so hard that it damages your blade.  Hi-soft (polyvinyl acetate), or end-grain wood boards are the most recommended cutting board materials.  All-rubber / Sani-tuff boards are also good.  If you are on a tight budget, you can get a cheap soft plastic (polyethylene) board, but they tend to scratch easier and are more difficult to clean.

Whatever you do, avoid cutting boards made of hard materials like bamboo, granite, stainless steel, hard plastic or edge-grain wood that will dull or damage your knife edge quickly.

Storage 

Day to day

After cleaning and drying your knife, there are a few options for day to day storage.

  • Magnetic Strip – You can mount it on your wall, or fridge.  This is a great, and cheap option for smaller kitchens, as it can save a lot of that precious counter space.  The only issue is that it does not offer any blade protection, but this shouldn’t be a problem if you pick a good spot that avoids anything banging into your knives.
  • Knife Block – The good ol’ knife block.  Comes in many styles and designs.  Usually made of wood.   It looks great, and also protects the blade, BUT, it can take up valuable counter space.  Make sure you buy one that is tall enough for your knives, and is “universal”, meaning you can insert knives anywhere in the block.
  • In a drawer – There are also some knife blocks / inserts that that fit within a drawer.  Great if you have an extra drawer to use.  If you are just putting your knife loose in a drawer, make sure you use a sheath or blade guard to protect the knife (and your fingers when reaching in).
Travelling

Some people like to travel with their knives (usually professional chefs).  There are plenty of great knife rolls, bags, and cases to choose from.  At bare minimum, make sure you have a blade guard on your knife.

Long term storage for carbon-steel knives

Here’s a cool tip if you are not planning to use your knife for awhile (i.e. long holiday, business trip, etc.).   First make sure the knife is completely dry, then wrap it in a bunch of newspaper.  Newspaper provides good breathability, and the ink can help prevent the blade from rusting.  Store your knife somewhere that is well ventilated with low air-humidity.

 

Sharpening

A good Japanese kitchen knife will maintain its sharp edge for a very long time, especially when compared to most Western made knives.  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 betterThis 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.

Sharpness Test

Is your knife sharp enough? 

A simple paper test is a good indicator of whether your knife needs to be sharpened or not.

Simply take a standard piece of printer paper, hold it up, and slice through it with your knife.  If you can easily make clean slices through the paper, then your knife is sharp!  See the video below for an example. (Via nozakitoru123 on Youtube. He’s not using a kitchen knife, but same rule applies):

Another simple test is to cut a sponge or tomato.  If you can easily, and cleanly slice through a tomato without using your off-hand to hold it, then your knife is sharp enough! See video below for an example (via Harry Kaufman on Youtube).

 

About Honing Rods

As a general rule, never use honing rods to sharpen your Japanese kitchen knife.  This has been mentioned by many chefs and knife experts much smarter than myself.

Quick fact:
Most honing rods don’t actually sharpen the blade.  They realign or straighten the knife’s edge after it has become bent/deformed from repeated use.  They are used frequently with softer German-steel knives, but are not recommended to use with Japanese knives.

So, why not use a honing rod on Japanese knives?  As mentioned earlier, a typical Japanese knife is made with a very hard steel (60 HRC or higher) compared to German steel knives (55~58 HRC).   Softer steel is more suitable for honing, as the edge can easily curl or deform with standard usage, and therefore can also easily be straightened out with a honing rod.

On the other hand, Japanese steel will not curl or deform, and therefore does not require honing.  Using a honing rod also runs the risk of chipping the harder, thinner, more brittle steel.  Therefore, there is no reason at all to use a honing rod with a Japanese knife.  If you feel your knife is getting dull, then it may be time to sharpen using a Japanese whetstone.  See below!

How to sharpen your Japanese knife with a whetstone (i.e. waterstone)

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 guide to sharpen a Western style Japanese knife (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.

Knife Sharpening Steps

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.

Another way to find the correct angle of your knife bevel is to use this marker/sharpie method, as explained by KnivesandTools:

6. Start sharpening.  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 (see image below), 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!

Every time you sharpen your knife, you are actually removing steel from your knife.  At first, you will probably be removing more material than necessary, but as you get more experienced you will be able to remove the minimum amount of material to create a sharp edge.

Sharpening your own knife is an intimidating task at first, but is an incredibly useful and satisfying skill to have for chefs.

For further instruction, check out these knife sharpening videos:

via Japanese Knife Imports on Youtube (English):

via 下村工業株式会社 (Japanese):

 

Conclusion:

In this article, we have gone over some general maintenance tips for Japanese knives (washing, usage, storage), and also a basic step-by-step sharpening guide for Western style Japanese knives (i.e.  double bevel).

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!

For more Japanese knife sharpening video resources, check out:
Japanese Knife Imports – Sharpening Playlist on Youtube
Korin Knives – Learn how to Sharpen playlist on Youtube

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