
Before Using a Japanese Knife – An Introduction to Japanese Knife Care
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A Japanese Knife Begins Its Journey Before the First Cut
At first glance, a Japanese knife may seem like just another kitchen tool. But once you hold it, you realize: this is a blade unlike any other. Its balance, its sharpness, and even its silence carry a question—"Will you treat me right?"
And no matter how beautifully crafted it is, a Japanese knife can lose its brilliance in an instant if used the wrong way. One careless move—cutting the wrong thing or storing it wet—can shorten its life drastically.
In this article, we’ll explore the essential "do nots" before you use a Japanese knife. But more importantly, we’ll explain why those rules exist. Because understanding the why behind Japanese knife care is what allows your knife to serve you faithfully for decades.
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1. Why Knowing What Not to Cut Comes First
One of the most common early mistakes is cutting something you shouldn’t.
I once saw a chef drive a brand-new Japanese knife straight into a frozen piece of meat. A loud crack followed. The edge chipped instantly.Japanese knives are designed for precision, not brute force.
Hard ingredients like frozen food, bones, or crustacean shells are too much for their fine edge.If you need to cut something hard, use a specialized blade like a deba. Using the wrong knife for the job isn’t just inefficient—it can destroy your blade in one second.
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2. Why Twisting or Hammering a Japanese Knife Is Dangerous
Have you ever used a knife to pry something open—like a frozen package or even a can lid? With Western knives, you might get away with it. But with a Japanese knife, that’s a recipe for disaster.
Japanese knives are incredibly strong when slicing forward or back, but extremely weak when bent sideways or twisted. This is because of how they are forged—thin, hard, and precise.
Even chopping with a vertical motion (like a "ton ton ton" rhythm) can damage single-bevel knives like yanagiba or usuba. These knives are meant to slide, not hammer.
The true beauty of a Japanese knife lies in the gentle glide—not the brute chop. -
3. Why Washing Techniques Matter More Than You Think
One of the fastest ways to ruin a Japanese knife is to treat it like your Western ones—by throwing it in the dishwasher or leaving it soaking in water overnight.
Many people assume, “It’s stainless, so it should be fine.”
But dishwashers use high heat and strong alkaline detergents, which can rust the blade, crack the handle, and swell the wood.If your knife is made with high-carbon steel like White Steel or Blue Steel, even soaking it for a few minutes can trigger rust.
Once, I left a freshly sharpened White Steel deba in a water-filled bowl overnight. By morning, red rust had already formed, and it took hours to fix.Rust happens in seconds. Restoration takes hours.
Always wash your knife by hand, using neutral detergent, dry it immediately, and store it properly.
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4. Why Proper Storage—and a Bit of Oil—Keeps Your Knife Alive
Many users ruin their knife not through cutting, but through improper storage.
If you store your knife while still wet, whether in a sheath or drawer, you’re creating the perfect environment for rust—especially in humid climates.
Store your knife in a well-ventilated place, and consider applying a light coat of camellia oil (tsubaki oil) from time to time. This traditional Japanese practice has been used for centuries to protect high-quality blades from moisture and air.
It’s not just about maintenance—it’s about respecting the tool.
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5. Why Using a Japanese Knife Means Living With It
You may not know if your first Japanese knife is “the one.” I didn’t either. I started with a Ginsan yanagiba, simply because I wasn’t confident in my maintenance skills.
But as I used it, I wanted to take better care of it. I started learning how to sharpen. I began to understand what it liked, and what made it dull.
The knife became part of my life—and my way of thinking began to change.
A mindful approach to cooking grew from the simple act of caring for a single knife. -
In Closing: Japanese Knife Care Is a Way of Life
Japanese knives can be delicate, even temperamental. But they’re also incredibly rewarding.
When treated properly, they respond with unmatched performance, beauty, and soul.Caring for a Japanese knife isn’t just tool maintenance—it’s a reflection of how you approach your craft, your ingredients, and your time.
The small effort you make today becomes tomorrow’s perfect slice.Believe in that—and walk this path with your Japanese knife by your side.
Why Does a Knife Lose Its Sharpness?
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If you cook regularly, you probably use a knife every day without giving it much thought. But at some point, you might notice: "My knife isn’t cutting as smoothly as before..."
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So, why does a knife become dull?
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The answer is simple: The edge wears down and becomes rounded over time.
Try sliding a dull knife lightly over your fingernail. A sharp blade would catch, but a dull one will simply glide across, offering no resistance. -
What Causes the Blade to Wear Down?
You might assume, "It’s the food I’m cutting, right?"
Not exactly.Surprisingly, most ingredients are much softer than the knife itself, meaning they are not the main cause of dullness.
So what is?
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The real culprit is the cutting board.
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When you cut food, your knife isn’t just making contact with the ingredients—it’s also hitting the cutting board every single time.
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But why doesn’t the cutting board get cut?
Because it’s much harder than the food you’re slicing. -
Each time your knife meets the cutting board, its edge gradually wears down. Over time, this constant contact rounds the blade, reducing its sharpness.
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That seemingly harmless cutting board is actually a major factor in how long your knife stays sharp. Understanding this can help you take better care of your knife and keep it performing at its best for years to come.
Why Does Chipping Occur?
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One unavoidable phenomenon when using a knife over time is chipping.
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Regardless of whether it is a professional or household knife, many people have experienced chipping at some point. Since knives are sharpened to a thin edge for cutting efficiency, they become extremely delicate, making chipping an inevitable fate.
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So, why does a knife blade chip?
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Main Causes of Chipping
In most cases, chipping occurs due to improper use. Specifically, chipping happens when unnatural force is applied to the blade. Let’s examine the most common scenarios.
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1. Excessive Force Beyond the Expected Limit
This occurs particularly when cutting hard ingredients.
Examples include fish bones and shells. Because these materials are difficult to cut, users may attempt to chop forcefully or push down heavily, which puts excessive strain on the edge and causes chipping.
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2. Applying Lateral Force
Knives are strong against vertical force but extremely weak against lateral force due to their thin blades.
For example, when cutting hard-skinned vegetables like pumpkins, the blade may not advance smoothly, leading users to twist or pry the knife. This motion applies lateral force, significantly increasing the risk of chipping.
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3. Cutting Frozen Ingredients
Using a knife on frozen meat or fish exerts unexpected stress on the blade.
Frozen ingredients are very hard, making it difficult for the blade to penetrate smoothly. As a result, users often twist the knife, leading to chipping. High-end knives with carefully tempered steel are particularly vulnerable to breakage at low temperatures.
Even if the surface appears thawed, the inside might still be frozen. Always ensure the ingredient is fully defrosted before cutting.
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4. Striking the Cutting Board Too Forcefully
Most people cut food on a cutting board, but they may not realize that they are also striking the board with the blade.
Since cutting boards are much harder than most ingredients, forcefully hitting the blade against the board can also lead to chipping.
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Other Factors That May Cause Chipping
While chipping is mostly due to usage issues, other factors can also contribute.
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1. Corrosion and Rust
If a knife is not properly maintained, rust can penetrate deep into the metal, weakening its structure.
When this happens, even after sharpening, the rusted areas remain structurally weak, making the blade more prone to chipping. Regular maintenance and thorough drying after use are essential.
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2. Overly Thin Sharpening
Sharpening improves cutting performance, but if a blade is sharpened too thin, even slight impacts can cause chipping.
While thin edges provide better sharpness, maintaining a balance between sharpness and durability is crucial.
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3. Improper Heat Treatment
Though rare, heat treatment issues during manufacturing can also lead to chipping.
If the tempering process is not properly controlled, the blade’s metal structure can become too brittle, making it prone to breaking under normal use.
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Conclusion
Although chipping is inevitable, proper knife usage can minimize its occurrence.
- Avoid forcing the knife through hard ingredients (e.g., fish bones and shells).
- Do not twist or pry the blade.
- Never use a knife on frozen food.
- Refrain from forcefully striking the cutting board.
- Regularly maintain and dry the knife.
- Sharpen the blade to an appropriate thickness.
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A knife is an essential tool for any chef. By following proper usage and maintenance practices, you can extend the lifespan of your knife and keep it in optimal condition.

The Cause of a Kitchen Knife Becoming Dull
A kitchen knife can become dull due to exposure to salt and acid, even in rust-resistant stainless steel knives. Bleach is particularly harmful as it can corrode the blade. Additionally, dishwashers can damage knives, affecting the handle and possibly leading to cracks. It is important to wash knives promptly after use, especially when cutting acidic or salty foods, and to dry them thoroughly to prevent rust and maintain their sharpness.

Things to Know to Become a Pro Knife User
To become proficient with knives, it's crucial to understand that knives are meant for slicing, not hitting. Professional chefs minimize noise by slicing cleanly, avoiding forceful contact with the cutting board. A well-maintained sharp knife doesn't require force, extending its lifespan and preserving its edge. Proper technique, such as slicing onions and scallions without crushing them, can prevent tears. Mastering these skills contributes to culinary precision and efficiency.

Free Special Services with Your Japanese Knife Purchase
At KIREAJI, we are committed to providing you with an authentic cutting experience and helping you enjoy the excellence of Japanese knives for a lifetime. Through our professional Honbazuke service and complimentary Saya, we are dedicated to supporting your journey with Japanese knives with the utmost care and attention.

The Origin of Craftsmanship
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Treating your tools with care is an opportunity to reflect on your attitude toward cooking.
For us traditional artisans, tools are not merely instruments for work; they are mirrors reflecting the heart of their user. Whether it’s a knife, cutting board, pot, or pan, the way these tools are maintained reveals the owner's mindset toward their craft. Well-cared-for tools tell a story of sincerity and respect for the art of cooking.
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Taking care of your tools is not just a task but a meaningful moment to connect with yourself. Sharpening a knife refines not only its edge but also your sense of handling ingredients. Keeping a cutting board clean enhances the precision and care in every step of preparation. These small acts of attention gradually manifest in the quality of your cooking.
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Loving and cherishing your tools goes beyond convenience or functionality. It deepens your appreciation for cooking, infusing every dish with greater care and intention. "To care for your tools is to love the craft of cooking itself."
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In the rush of daily life, it’s easy to overlook the upkeep of your tools. However, dedicating even a little time to this practice can lead to a rediscovery of the joy and depth of cooking. Take a moment to connect with your tools—you may find that both your meals and your spirit become richer and more fulfilling.

Would you like to experience the sharpness of handcrafted knives from Sakai City, used by 98% of Japanese chefs?
Through our exclusive partnership with Shiroyama Knife Workshop, we bring you top-quality knives. In addition, we offer free Honbazuke sharpening, a protective Saya, and paid after-sales services to ensure long-term confidence.
KIREAJI's Three Promises to You
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1. Exceptional Japanese Knives
Our knives, crafted by Sakai City's master artisans, combine traditional techniques with carefully selected materials, delivering unrivaled sharpness and durability.
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2. For a Lifetime of Use
At KIREAJI, we see knives as lifelong companions. Each knife comes with a free saya, and we offer Honbazuke hand-sharpening by Shiroyama Knife Workshop in Sakai City.
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3. Supporting the Joy of Continued Use
KIREAJI knives are made to grow with you. That’s why we provide trusted after-sales care (fee-based) .