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How to Sharpen a Japanese Knife

12 Mins read
How to Sharpen a Japanese Knife

Every chef or home cook should possess the skill of sharpening a Japanese knife. These knives are renowned for their exceptional quality, sharpness, and durability. However, similar to any other knife, they can lose their sharpness with regular use. Maintaining the sharpness and performance of your Japanese knife requires proper sharpening. In this article, we will provide tips and techniques on how to sharpen a Japanese knife. Whether you are a professional chef or a home cook, with the right tools and techniques, you can effortlessly keep your Japanese knife in top condition for many years.

What is a Japanese Knife?

Japanese knives are highly regarded cutting tools with a rich history originating from Japan. Renowned for their exceptional sharpness, precision, and cutting ability, these knives are crafted using high-carbon stainless steel blades that maintain an incredibly sharp edge. With blade angles ranging from 15 to 18 degrees per side, Japanese knives offer outstanding accuracy for precision cutting. Designed for specific tasks, such as the Santoku for chopping, the Gyuto resembling a chef’s knife, the Nakiri for vegetables, and the Sujihiki for slicing meats, they cater to diverse culinary needs. These knives typically feature traditional wooden handles, providing a secure and non-slip grip.

Japanese knives require periodic sharpening using a whetstone and careful maintenance to preserve their cutting prowess. Proper care involves thorough washing, complete drying, and the application of a protective coat of oil to the blade. It is advisable to avoid harsh detergents that may degrade the knives’ quality. By observing these guidelines, a top-quality Japanese knife can serve as an indispensable tool for professional chefs, home cooks, and culinary enthusiasts for many years.

How to Sharpen a Japanese Knife

A Japanese Knife

Why Do You Need A Sharp Japanese Knife?

A sharp Japanese knife is a must-have for any serious home or professional cook. Japanese knives are renowned for their ability to maintain an exceptionally sharp edge, thanks to the high-carbon stainless steel used for their blades. The precision slicing and smooth motion made possible by a sharp knife require less force, making it not only efficient but also safer than a dull knife that requires extra pressure.

Moreover, a sharp Japanese knife ensures that foods are cut through efficiently without squashing or tearing them, preserving their shape, texture, and moisture. It effortlessly handles tasks such as chopping vegetables, slicing meat, and filleting fish, enabling you to achieve paper-thin cuts for salads or garnishes. The precision and accuracy offered by a sharp knife also contribute to the overall presentation of your dishes.

To maintain the longevity of a quality Japanese knife, proper care is crucial. Regular sharpening, honing, and oiling help to preserve the blade’s edge. However, even the hardest steel blade will eventually dull with frequent use. A dull knife requires frequent re-sharpening and presents increased safety risks and hampers the cutting process, leading to frustration and tedium. Therefore, investing in a sharp and durable Japanese knife, along with learning proper knife skills and care techniques, is indispensable for any home cooking enthusiast. With the right knife and proficient hands, cooking transforms into an art form.

When You Should Sharpen Your Knife?

Maintaining a sharp blade is crucial to optimize your cutting experience when using a knife. A sharp knife boasts several advantages over a dull one, including enhanced safety, improved efficiency, and cleaner cuts. Here are a few signs indicating it’s time to sharpen your knife:

1. Excessive pressure is required to cut through foods. A sharp knife should slice effortlessly with minimal force.

2. The knife tears or crushes soft foods instead of making clean cuts.

3. Sudden slippage on food surfaces, making them unsafe. Dull blades require more pressure and are more prone to slipping.

4. The knife’s edge retention diminishes significantly. If honing the blade with steel doesn’t restore performance, sharpening is likely necessary.

5. The appearance of a “wire edge” or “burr” along the sides of the cutting edge. This thin, folded-over metal piece impairs cutting ability and must be sharpened off.

6. The knife no longer exhibits the precision or accuracy required for specific tasks such as vegetable slicing, fish filleting, or meat carving.

When sharpening, aim to remove around 1/16 of an inch or less from the blade’s surface. Stop once a new edge is formed, regularly assessing your progress. Remember that frequent sharpening can reduce the lifespan of a knife.

For home cooks, sharpening a knife every 3 to 6 months is typical, depending on the frequency of use and types of cuts performed. In commercial kitchens, knives often require sharpening every 1 to 3 months. With regular home use and proper care, a high-quality knife can last a lifetime if sharpened before the edge degrades completely. Keep your knives sharp for smooth slicing!

How to Sharpen a Japanese Knife

How to Sharpen a Japanese Knife

How to Sharpen a Japanese Knife – 3 Sharpening Strategies

Sharpening a Japanese knife is an important skill to master to maintain the knife’s sharpness and longevity. There are different sharpening strategies you can use depending on the type of Japanese knife you have, the level of dullness, and your personal preference. Here are three common sharpening strategies for Japanese knives:

How to Sharpen a Japanese Knife by The Whetstone Method

Sharpening a Japanese knife using the whetstone method is a traditional technique to ensure its longevity and optimal sharpness. Here are the steps:

Gather sharpening stones: You will need a coarse stone (around 220 to 400 grit), a medium stone (around 800 to 1000 grit), and a fine stone (at least 3000 grit) for polishing the edge. You may also use a flattening stone to prepare the whetstones.

Set up your work area: Place a damp cloth or paper towel underneath the whetstones to prevent slipping. Keep a container of honing oil or water nearby to lubricate the stones. Find a flat surface where you can securely hold the stones while working.

Lubricate the coarse whetstone: Follow the manufacturer’s instructions to apply oil or water to the coarse whetstone. Place it on your work surface with the coarser-grit side facing up.

Grind the knife: Hold the knife handle firmly and place the blade almost flat against the stone. Grind the blade using even pressure, pushing the knife along and away from the edge, covering the entire stone surface. Repeat on the other side.

Check for burr formation: Repeat the grinding on both sides until a “burr” or edge is formed on each side of the blade. Verify by gently sliding your finger from the spine to the edge. Flip the blade over and repeat until a burr is formed on both sides.

Polish the edge: Use the medium and fine grit stones to further polish the edge until it becomes exceptionally sharp. Test the sharpness by gently sliding the edge under your thumbnail. It should catch slightly.

Achieve a mirror-like finish: Lubricate the highest grit whetstone (8000+ grit) and glide the edge along the stone with very light pressure. Repeat on the other side until you achieve a mirror-like finish.

Remove the burr: Slide the edge perpendicularly over each stone, with the grit side up, to remove the burr. Repeat on the other side. The edge should now be exceptionally sharp with no catch.

Rinse, dry, and protect: Rinse the blade, dry it thoroughly, and apply an oxidation-preventing oil. For storage, use a blade guard to protect the edge and prevent injury. Take care to keep oils off other tools and surfaces.

Remember to handle and store the knife cautiously once sharpened. Regular honing will help maintain its sharpness, and repeat the whetstone process when the blade becomes dull. With practice, you will achieve excellent cutting-edge using high-quality Japanese whetstones.

How to Sharpen a Japanese Knife

How to Sharpen a Japanese Knife

How to Sharpen a Japanese Knife by The Honing Rod Method

The honing rod method, also known as honing or stropping, is a technique used to maintain the sharpness of Japanese knives between sharpening sessions. Here are the steps to sharpen a Japanese knife using the honing rod method:

Gather a honing rod designed for Japanese knives. A ceramic rod with a fine grit (at least 2000 grit) works well for the hard steel in Japanese knives. Smooth, crossed knife rods can also work.

Hold the knife handle and place the heel of the blade against the rod at a 15-degree angle. Slowly slide the edge along the rod using even pressure until you reach the tip. Repeat on the other side.

Repeat step 2 using light, alternating passes on each side of the edge until the edge becomes razor-sharp. This typically takes 5 to 10 passes per side for a moderately dull edge. Check the sharpness of your thumbnail periodically.

For polishing the edge, hold the sides of the blade almost flat against the rod and slide from heel to tip using very light pressure. Repeat on both sides until a mirror finish appears on the cutting edge.

Remove any burrs by gently scraping each side of the edge against the rod, corner to corner, at a 90-degree angle. Repeat on the opposite side. The edge should now feel exceptionally sharp and smooth.

Test and inspect the edge for sharpness. It should easily slice through paper or shave arm hair. Look for any uneven or dull areas along the edge and repeat honing as needed.

Once satisfied with the sharpness, clean, dry, and protect the blade. Apply a coat of honing oil or wax to prevent oxidation. Cover the edge or store the knife in a sheath when not in use.

For minor touch-ups between major honing, just a few light passes over the honing rod are required to realign and restore the edge. Check and test sharpness to ensure even honing along the entire edge.

With high-quality Japanese knives, honing rods provide a quick method for maintaining the edge between sharpenings on whetstones. However, to repair any damage, chips, or dullness in the edge, the use of Japanese Waterstones is typically required. Frequent honing and proper knife care will keep your Japanese knives slicing smoothly.

How to Sharpen a Japanese Knife by The Electric Sharpeners Method

Electric sharpeners are a convenient and popular option to sharpen Japanese knives. Follow these steps for sharpening a Japanese knife with an electric sharpener:

Select an electric sharpener specifically designed for Japanese knives. Look for a model with multiple slots for different blade angles, including a 15-degree setting, which is standard for most Japanese knives. It should also have fine grit and polishing stages suitable for the hard steel found in Japanese blades.

Make sure the sharpener is placed on a steady, flat surface and that the collection bin is empty. The sharpener needs to remain stable as you pass the knife through the slots.

Before sharpening, lubricate the knife and the sharpener slots with honing oil following the instruction manual. Avoid using water, as it may damage certain electric sharpeners.

Set the guide on the sharpener for a 15-degree bevel angle. Firmly hold the handle and align the edge in the guide slot. Pull the knife through the slot, applying even pressure until the entire blade edge passes through. Repeat this motion for each subsequent slot.

Make several passes through each slot, checking the sharpness in between. Typically, electric sharpeners require 3 to 6 passes in each stage (from coarse to fine) to restore the edge. Assess the sharpness by performing the paper test – slicing through paper held in mid-air. Repeat stages as necessary.

When using the polishing slots, make 1 to 2 passes through each slot using very light pressure. Avoid over-polishing, as it can weaken the edge. Check for sharpness and whether a mirror finish appears along the edge. Repeat the final polishing slot if needed.

Remove any wire edge or burrs by passing each side of the blade edge-first through a fine-grit slot at a 90-degree angle. Wipe away any remaining filings or debris from the blade surface and edge. Test the sharpness of the edge by slightly scraping your thumbnail against it, which should catch slightly.

Clean the sharpener according to the directions provided after use to remove any metal filings. Embedded filings can dull future sharpening results. Dispose of or empty the collection bin.

Protect the sharpened edge by wiping it clean, drying it, and applying honing oil. Sheath the blade or use blade guards until the next use.

Electric sharpeners can quickly restore an edge, but they may remove more metal than necessary and require frequent cleaning. For the ultimate sharpness of Japanese knives, whetstones are recommended. It is best to use electric sharpeners periodically or when signs indicate the edge needs resetting between stone sharpenings. With proper care, your Japanese knives will maintain their sharpness for years to come.

How to Sharpen a Japanese Knife

How to Sharpen a Japanese Knife

Can You Use An Electric Sharpener On A Japanese Blade?

It is possible to use an electric sharpener on a Japanese knife blade, but it does come with some trade-offs compared to manual whetstone sharpening:


Speed and convenience. Electric sharpeners can quickly sharpen a dull edge. This is good for a quick touch-up when a whetstone is not practical.

Angled guides. Most electric sharpeners have adjustable guides to hold the blade at the proper angle, typically 15 degrees for Japanese knives. This helps ensure an even edge, especially for beginners.

Multiple stages. Quality electric sharpeners have multiple slots with progressively finer abrasives to sharpen and polish the edge. When used properly, they can produce a sharp edge.


Material removal. Electric sharpeners are more aggressive and remove more blade material to form an edge. This can shorten the lifespan of the knife over time with repeated use.

Heating. The friction from electric sharpeners can heat the blade, damaging the temper. This is more likely if sharpening slots are narrow, multiple passes are made or pressure is too high. Proper lubrication and care must be taken.

Cleaning. Electric sharpeners require frequent cleaning to prevent built-up metal filings which can scratch and dull the edge. Filings left on the blade must also be wiped away after sharpening.

Edge quality. Whetstones in skilled hands generally produce a sharper, longer-lasting edge than electric sharpeners. The Polish effect is also harder to achieve.

Non-uniform. The edge can become uneven, developing ‘waves’ or dips with repeat electric sharpener use. Whetstones provide more control.

For occasional quick touch-ups of a Japanese knife, an electric sharpener may suit your needs, especially for beginners still learning proper skills. However, for the initial sharpening of a quality Japanese knife and to achieve an optimal, even edge that preserves the blade, whetstone sharpening by a skilled sharpener is typically recommended. With the right technique and care, you can certainly extend the life of your Japanese knives using an electric sharpener, but whetstones remain the gold standard.

How to test your knife’s sharpness

There are multiple ways to determine the sharpness of your knife:

Thumbnail test: Gently drag the knife’s edge against your thumbnail. A sharp knife will slightly catch on your nail, while a dull knife will slide smoothly. Be cautious while conducting this test to avoid cuts.

Paper cutting test: Hold a sheet of paper in mid-air and slice it into the edge of the paper with the knife. A sharp knife will cleanly cut through the paper, while a dull knife will tear the paper or struggle to cut. Newspaper is a good choice as it is more resistant to cutting.

Tomato test: Pierce the skin of a tomato smoothly by slicing it in one motion. A sharp knife will smoothly penetrate the skin and cut through the flesh, while a dull knife will squish the tomato and tear the skin.

Finger pad test: Gently and carefully drag the knife’s edge against the pad of your finger using even pressure. A sharp knife will give the sensation of lightly splitting the skin without actually cutting it, while a dull knife will slide without that feeling. Use minimal pressure and exercise extreme caution.

Onion/carrot chopping test: Attempt to dice an onion or slice carrots. A sharp knife will effortlessly glide through the vegetable, producing uniform square cuts with minimal cracking in a single stroke. On the other hand, a dull knife will require sawing back and forth, resulting in sloppy and uneven cuts.

Scalpel sharp test: Carefully shave a few arm hairs to determine if the knife effortlessly slices through. Hold the knife firmly and proceed with extreme caution. Only use hair from the lower forearm for this test. A sharp knife will easily shave hairs, while a dull one will pull at them.

The sharpness of high-quality knives deteriorates over time and usage. Conducting regular tests allows you to monitor your knives and determine when it’s time for honing or sharpening to restore the edge. With regular maintenance and care, your knives will retain their sharpness and last a lifetime.

How to Sharpen a Japanese Knife

How to Sharpen a Japanese Knife

How to store your knives to keep them sharp

Here are some helpful tips for storing your knives and maintaining their sharpness:

1. Use a knife block or magnetic rack to keep knives off the counter and protect their edges. Knife blocks ensure easy access, while magnetic racks securely hold knives.

2. Keep knives apart when storing in a drawer. Use separate compartments or knife guards/sheaths to prevent the edges from touching. Dividers can also help organize knives.

3. Avoid loose storage by using dividers, racks, blocks, or sheaths to keep knives in place. Haphazardly throwing knives into a drawer can quickly dull their edges.

4. After washing, thoroughly dry knives to prevent rusting, even for high-carbon stainless steel knives. Drying not only saves the edges but also polishes them.

5. Apply honing oil to coat the edges of carbon steel knives and protect them from oxidation. For stainless steel knife edges, wipe them clean and occasionally apply a thin coat of oil to prevent rust spots.

6. Be careful not to drop or bang knives, as this can chip the edges and dull the blades. Grip knives by the handle and use cutting boards to avoid contact with hard countertops.

7. Maintain sharpness by regularly honing and sharpening your knives. Sharp edges last longer and require less maintenance compared to dull ones. Professional sharpening may be needed when knives no longer slice effectively.

8. Limit dishwashing and hand wash knives separately to prevent dulling in the dishwasher. The harsh detergents and contact with other utensils can damage the edges. Dry knives immediately to avoid spotting.

By following these guidelines for proper storage, handling, washing, and sharpening, you can enjoy sharp, polished, and rust-free knives for many years of slicing and dicing.

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About author
As the founder and chief editor of Scills Grill, I'm a self-proclaimed BBQ nut. I love cooking outdoors over live fire and smoke, no matter the weather. I use various grills, smokers, and wood-fired ovens to produce epic food. Peter Cobbetts is the president and founder of Scills Grill, with over 15 years' experience in barbecue. He's an exceptional pitmaster and grill expert who specializes in smoking briskets, pork shoulders - using charcoal, wood or propane grills/smokers - as well as reviewing kitchen appliances such as grills, smokers etc., having tried out almost every model available on the market.
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