Manufacturing Process of Japanese Knife

  • To begin with, Japanese knife manufacturing processes are broadly categorized into "forging" and "casting." This page aims to explain these methods in detail and help you understand their differences.

  • Forging involves shaping metal by hammering it to achieve the desired form. The metal is heated and hammered, which aligns and compresses the internal crystal structure. This process results in a more durable and resilient material. The toughness gained from forging is known as "toughness," which refers to the material's resistance to impact and sudden force.

  • On the other hand, casting involves melting the metal and pouring it into a mold, where it solidifies as it cools. While cast products may look similar to forged ones, their internal structure differs. Casting allows for mass production and uniform shapes quickly and cost-effectively, making it suitable for producing large quantities of products.

  • Differences Between Forging and Casting

    • Appearance: Forged and cast products may look similar, but there is a significant difference in their internal quality.
    • Strength: Forging compresses and aligns the metal's crystal structure, resulting in enhanced strength and toughness. Casting, however, has a coarser internal structure, leading to lower strength and toughness.
    • Cost and Production Efficiency: Casting is ideal for mass production and cost reduction, but forging involves more time and effort, resulting in higher quality products.

  • At KIREAJI, we offer Japanese kitchen knives forged by craftsmen in Sakai City. This page will delve deeper into the details of the forging process and highlight its techniques and appeal.

Ⅰ. Forging Process: Traditional Techniques to Shape and Strengthen the Blade

  • Forging is the process of shaping metal by hammering it. In this process,soft iron and steel, which serve as the base materials, are heated until they are glowing red. By heating the metal to make it malleable, it becomes easier to process and shape into the desired form. Hammering the metal not only extends its shape but also densifies the internal structure, enhancing its strength and toughness. This method creates a blade with exceptional sharpness,durability, and remarkable beauty.

  • 1. Forge Welding (Wakashitsuke)- High-Temperature Metal Bonding

  • Forge welding involves heating metal to approximately 1100-1200 degrees Celsius, making it pliable for bonding through hammering. This technique, traditionally known as "Wakashitsuke" in Sakai City, is used to heat soft iron and bond it with steel, creating a durable blade. This high heat allows the metals to fuse effectively, ensuring both strength and sharpness in the final product.

  • Temperature Control in Wakashitsuke - The Art of Enhancing Sharpness

    In the Wakashitsuke method, precise temperature control is critical to the quality of the knife. If the temperature is too low, the metals won’t bond sufficiently, while excessive heat can damage the steel. This meticulous temperature adjustment enhances the blade’s sharpness, allowing artisans to fine-tune each knife’s edge. Working at lower temperatures helps maximize the knife’s sharpness, and the craftsman’s ability to assess the ideal temperature by sight is key. A slight temperature miscalculation can lead to defects in the blade, so artisans carefully monitor the temperature and handle each blade with exceptional attention to detail.

  • Combining Soft Iron and Steel - A Legacy of Japanese Sword Crafting

    Japanese knives often feature layers of soft iron and steel, combining different materials for optimal flexibility and strength. This technique is derived from traditional Japanese swordmaking, imparting superior durability and sharpness to the blade. Sakai artisans strongly believe that "using the finest materials is essential" in knife making and select each element with utmost care.

  • The Pinnacle of Blacksmithing: Pursuing the Ideal Knife – The Art of Temperature Control and Fine Grain Structure

    In the art of knife-making, the key to crafting the perfect blade lies in the fineness of the metal’s grain structure. This fine grain determines the precision of the edge and its cutting performance. At the same time, precise temperature control during forging is indispensable. If the temperature is too low, shaping the metal becomes difficult; if it’s too high, the grain structure coarsens, compromising the blade's sharpness and durability.

  • Ancient blacksmiths mastered the delicate balance of maintaining the metal’s fine grain by forging it meticulously at low temperatures. They observed the metal’s color and texture to determine the right moment to strike. This intricate temperature management is a testament to their expertise, ensuring the internal structure of the metal remains optimized to maximize its potential.

  • A knife is not merely a tool—it serves as an extension of the chef’s hand, unlocking the full potential of ingredients. When crafted with fine-grained metal and the artisan’s skill, the blade’s edge becomes sharp and uniform, cutting effortlessly without damaging the food. This ensures that the flavor, texture, and natural beauty of the ingredients are preserved, elevating the culinary experience.

  • The harmony between craftsmanship and natural materials, honed over centuries, surpasses even the most advanced modern technologies and synthetic materials. Knife-making is a process that requires delicate control of heat and pressure, minimizing stress on the metal. Through careful low-temperature forging, the internal structure of the blade is refined, producing a flawless edge when polished.

  • Each knife is imbued with the passion and dedication of the artisans who create it. The ideal blade not only supports the craft of the chef but also embodies the harmony between nature and human skill. Through their work, artisans deliver a sense of reverence and inspiration, connecting the hands of the maker to those of the user. This is the essence of knife-making—a blend of functionality, artistry, and timeless beauty.

  • Yasuki Steel - Known for Its High Purity and Superior Sharpness

    Sakai knives use Yasuki steel from Shimane Prefecture, a high-purity steel containing minimal impurities like phosphorus and sulfur, which can affect sharpness. Known for its exceptional cutting performance, Yasuki steel demands delicate temperature management, a skill limited to only the most experienced craftsmen.
Yasuki Steel

  • The Miracle of Sharpness Born from 600 Years of Tradition: The Essence of Sakai Knives

    Sakai knives are celebrated by chefs both in Japan and abroad—not just for their exceptional sharpness but for something far greater. These knives preserve the cellular integrity of vegetables, enhancing the natural aroma and flavor of ingredients. This remarkable capability stems from over 600 years of tradition and the masterful craftsmanship of Sakai’s artisans.

  • The lifeblood of a Sakai knife is forged in flames exceeding 1,000°C (1,832°F) by the hands of skilled traditional craftsmen. What sets these knives apart is their unique structure, where a hardened steel blade and a softer iron core are seamlessly fused together. The craftsmen explain their technique simply but profoundly: "We heat the materials until red-hot and hammer them into one." This fusion, perfected over decades of experience, gives Sakai knives their legendary sharpness, durability, and precision.

  • The crafting process is nothing short of mesmerizing. A strip of iron, about 5 cm wide and 1 cm thick, is heated in a gas furnace until it glows orange. A piece of steel, roughly 10 cm long, is then placed on top before returning to the flames. When the steel starts to bubble, the craftsman swiftly removes it and hammers the materials together. "Forging the steel just before it melts creates a fine, uniform structure, enhancing sharpness," the master explains.

  • To ensure a perfect bond, a borax-based adhesive is sprinkled on the surface, and the process is repeated, gradually shaping the knife. Once the blade takes form, it is slowly cooled in straw to prevent deformation. The final touch involves heating the blade to nearly 800°C (1,472°F) and quenching it rapidly, creating a balance of hardness and resilience. Every strike of the hammer, every adjustment to the temperature, contributes to a knife that transcends mere utility.

  • The artistry of Sakai knives lies in the harmony of fire, steel, and the human touch. These knives are more than tools—they embody a legacy of respect for materials and an unwavering commitment to quality. They offer not just precision but an experience of “cutting with soul.”

  • Owning a Sakai knife means holding a piece of history in your hands—a miracle of craftsmanship that has inspired chefs around the world for centuries. Wouldn't you like to experience the wonder of these legendary knives for yourself?

  • 2. Preliminary Forging

  • In this stage, the craftsman skillfully alternates between a mechanical spring hammer and a hand hammer, carefully shaping the heated soft iron and steel. This traditional forge-welding process, called wakashitsuke, ensures the metals are thoroughly bonded at high temperatures, creating a strong, unified blade structure. After bonding, the blade is reheated and shaped to its final form. Through this cycle of heating and hammering, the steel's internal grain structure is refined, resulting in exceptional sharpness and cutting performance.

  • For example, forging a 300mm Yanagiba knife made of Shirogami steel takes about 20 minutes with a hammer. However, performing the same process with Aogami steel requires roughly twice as long because Aogami steel is significantly harder. Shirogami steel visibly stretches under hammering, while Aogami steel initially shows almost no change. This difference demonstrates the unique handling challenges of each type of steel, as well as the time and skill required from the craftsman to bring out their best qualities.

  • 3. Core Taking and Shaping

  • From the pre-cut steel material, a single knife is cut out, forming what is known as the han-gata, which serves as the base of the knife. Next, the core that will be placed inside the handle of the knife is made. Since cutting ability is not required, it is created from base metal.

  • Once the core is made, the blade tip is shaped. This process is called shaping. During this time, the base is left thick while tapering down to a thinner edge (known as a taper structure or tapering). This technique sharpens the cutting edge and reduces weight, resulting in a knife that is less tiring to use.
Japanese Knife Structure

  • 4. Annealing (Yaki-namashi)

  • Annealing is a crucial step in knife production, aimed at removing internal stress after forging and softening the steel structure to improve workability. In the production of Sakai knives, traditional methods are employed, with the steel being slowly cooled over a full 24-hour period. This process adjusts the hardness and resilience of the material, enhancing the knife's overall quality and sharpness. While many craftsmen use mechanical furnaces to manage the temperature, there is also a method where the steel is placed in ash after burning straw, which helps prevent carbon evaporation and creates a more robust metal structure. The craftsmanship of the artisans ensures that this annealing technique maintains the high reputation of Sakai knives.

  • Ⅱ. Heat Treatment Process: Refining the Steel's Properties for Optimal Performance

    A precise process of temperature control and cooling to enhance hardness, strength, and toughness

  • 1. Rough Forging

  • Rough forging is one of the essential processes in the production of knives. During this stage, a hammer is used to strike the surface of the blade, removing the oxide film. Subsequently, a spring hammer is employed for further forging. This effectively eliminates the oxide film formed during the fire forging process and results in a smoother blade surface.

  • This smooth surface makes the subsequent work of the sharpener much easier and significantly impacts the final quality of the blade. By undergoing the rough forging process, the knife's edge evolves into a more precise and sharper cutting tool.

  • 2. Urasuki

  • Urasuki is the process of creating subtle indentations on the back surface of a knife, a task performed by skilled artisans. The craftsman uses a hammer to carefully strike the back of the blade. This delicate indentation allows for reduced contact area between the food and the blade, resulting in a smoother cutting experience.

  • By applying urasuki, food is able to release easily from the knife, enhancing the efficiency of food preparation. This effect can be particularly appreciated when cutting various ingredients such as meat, fish, and vegetables, making it an essential process for chefs. Thus, urasuki plays a crucial role in enhancing the performance of the knife.
Urasuki

  • 3. Quenching (Yaki-ire)- The Moment Life is Breathed into the Knife

  • Quenching is the most crucial and tension-filled process in knife making. It wouldn't be an overstatement to say that the success of all previous work depends on this single process.

  • Meticulous Preparation and Careful Techniques

    Before quenching, a special clay mixture is applied to the blade. This clay serves several vital purposes:

    • Prevents uneven heating
    • Enhances cooling efficiency when submerged in water
    • Ensures uniform hardness throughout the blade

    The workshop is intentionally darkened. This allows the master craftsmen to precisely observe the subtle color changes in the steel - a skill that only comes with years of experience.

    The Critical Moment

    The high-purity Yasuki steel (Yasuki-hagane), due to its exceptional purity, demands incredibly precise temperature control. At this crucial moment, the craftsman must identify the exact instant when the steel reaches its ideal temperature. Then, without a moment's hesitation, the blade is plunged into water.

    The Science Behind the Art

    During the quenching process, several transformations occur:

    1. The heated steel rapidly absorbs carbon
    2. Rapid cooling fixes the carbon in place
    3. Through this process, the steel achieves its ultimate hardness

    Master Craftsman's Wisdom

    The hardened steel has a tendency to warp. Drawing from generations of experience, craftsmen employ a clever technique: they pre-bend the blade in the opposite direction to ensure it straightens properly during quenching. This represents another crucial aspect of the master craftsman's expertise.

    Words from the Master

    "The quenching process determines the blade's cutting edge. A single mistake during this stage renders all previous work meaningless. Working with high-purity Yasuki steel is particularly challenging, demanding our utmost attention to temperature control. A split-second decision breathes life into the blade - or destroys it."

    This crystallization of skill and experience - the quenching process - truly represents the moment when the soul is breathed into a Sakai knife.

  • Phase Transformation Points

    Austenite:

    When metal reaches a certain temperature (approximately 800 to 850 degrees Celsius), iron, carbon, and trace elements dissolve and mix uniformly. This state is known as austenite. This phase, also referred to as austenitic transformation, makes the metal softer and easier to work with.

    Martensite:

    By rapidly cooling the austenite, a harder microstructure known as martensite is formed. Rapid cooling is crucial for achieving this structure, which results in a significantly harder material. This phase transformation is known as martensitic transformation, and the greater the amount of carbon in the iron, the harder the material tends to become.

    The Secrets Behind Knife Warping: A Master Craftsman's Perspective 

  • From the perspective of a traditional craftsman

  • Breathing Life into Metal: The Soul of a Blade Born Through Cooling

    Cooling is not just a process; it is the very act of transforming the essence of metal. By applying stress through precise cooling techniques, we alter its structure and awaken its potential. This critical step unlocks the hardness and durability essential for crafting fine blades.

  • In the world of traditional craftsmanship, cooling is seen as more than science—it’s a moment of artistry where the material’s spirit is shaped. By controlling the speed and method of cooling, whether rapid quenching or gradual air cooling, we dictate the character of the blade.

  • This process embodies the philosophy of balance and precision. Without proper cooling, the metal reverts to softness, losing its ability to hold an edge. It’s in this moment, as the heat dissipates and the structure tightens, that the blade’s true nature is born.

  • Importance of Quenching

    Quenching is essential for dramatically improving the hardness and durability of metal. The transformation from austenite to martensite through this process significantly enhances the metal's performance. As a result, quenching produces a metal that is stronger and more durable.

  • Let's dive into a more intriguing aspect of quenching: the methods used for rapid cooling. There are primarily two methods for quenching: water and oil. The process of quenching with water is called water quenching, and the process using oil is called oil quenching.

  • Water quenching cools the metal extremely rapidly, resulting in a very high quenching rate. In contrast, oil quenching cools the metal more gradually, with a slower quenching rate compared to water quenching.

  • The speed of cooling significantly affects the formation of martensite. Martensitic transformation occurs when the metal transitions from austenite to martensite. The faster the cooling rate, the more robust the martensite structure becomes. In other words, the quicker the quenching process, the more effectively martensite forms. Thus, water quenching, with its rapid cooling capability, tends to produce a superior martensite structure and is generally considered to provide better quality.

  • However, some people prefer oil quenching for its specific advantages. While water quenching is often seen as superior in terms of the microstructure of martensite, oil quenching has its own set of benefits, which can be a matter of personal preference. Therefore, while water quenching is typically favored for its performance in creating a strong martensite structure, oil quenching also has unique advantages that may be preferred by some.

  • Mastering the Flame: The Art, Wisdom, and Passion of Traditional Japanese Forging

    The ability to control fire in the forging process is at the heart of Japan's traditional craftsmanship. In the critical quenching stage, artisans rely on a unique tool called a furnace bellows (fuigo) and fuel it with pine charcoal—a choice deeply rooted in practicality and tradition. The bellows allow for precise temperature adjustments, ensuring that heat is evenly distributed from the blade’s edge to its body. Pine charcoal is the ideal fuel, as it ignites efficiently with minimal airflow and produces a robust flame.

  • The quenching process is conducted at temperatures between 740 and 780 degrees Celsius, with the exact moment determined by the artisan's keen sense and experience. Mastering the ability to discern the perfect hue of the flame—an essential skill for producing high-quality results—takes 7 to 10 years of dedicated training. This long and arduous journey embodies the relentless pursuit of excellence inherent in Japanese craftsmanship.

  • Even the choice of charcoal reflects this dedication. At A-san’s workshop, only pine charcoal from Iwate Prefecture is used, underscoring the importance of every detail. Each decision contributes directly to the final product’s superior quality and authenticity.

  • Traditional Japanese forging is not just a technical process—it is a harmonious interplay of nature and human ingenuity, a testament to centuries of accumulated wisdom. Understanding this intricate background allows one to truly appreciate the profound value imbued in each handcrafted piece.

  • 4. Tempering (Yaki-modoshi): A Crucial Step to Impart Toughness and Balance

  • Tempering is a vital process that gives a blade its distinctive toughness by balancing hardness and flexibility. This step involves reheating the hardened steel from the quenching process to an optimal temperature and then cooling it, ensuring the perfect balance between strength and resilience. For example, a Deba knife (330mm) is heated at 180°C for 30 minutes and then air-cooled, achieving its finest state.

  • The purpose of tempering is to relieve internal stress and correct any distortions in the blade while preserving its strength. The temperature setting is crucial—too high, and the hardness decreases; too low, and the blade lacks flexibility. This precision relies on the craftsman’s experience and intuition, honed over many years of practice.

  • Mastering the Cooling Process

    In addition to heat treatment, the cooling process plays a critical role. During water cooling, factors such as water temperature and quality are meticulously adjusted. Craftsmen say, "The key lies in considering the expansion rates and tailoring the water quality and temperature." Such attention to detail ensures that no element is overlooked.

  • A Blend of Artistry and Precision

    Tempering is not merely a technical task—it is the art of shaping the soul of a blade. Each knife is infused with the artisan’s skill and passion, creating a tool that transcends functionality to become a cherished masterpiece. The delicate balance of hardness and flexibility ensures that the knife not only performs flawlessly but also lasts for generations, embodying the craftsmanship and dedication of Sakai’s master artisans.
Japanese Knife Materials 4 points

Sub-Zero Processing

KIREAJI's Sub-Zero processing technology rapidly cools steel to sub-zero temperatures, significantly enhancing knife hardness and durability. This process, rooted in the craftsmanship and expertise of skilled artisans, results in knives with superior sharpness and lasting performance.

Sub-Zero Processing

Discover the Allure of Forged Knives

Forged knives represent the pinnacle of craftsmanship, where strength, durability, and beauty converge.

Discover the Allure of Forged Knives

Technical Explanation of Aike in Japanese Traditional Knives

In traditional Japanese knives, "Aike" is a unique phenomenon that can significantly impact the blade's quality. Are the staff at the store you're considering aware of Aike? Many shops sell knives without completing the final sharpening process, leading customers to unknowingly purchase knives with Aike. This page delves into Aike's technical aspects and why it matters for your knife selection.

Aike

  • Ⅲ. Sharpening: Mastering the Edge for Ultimate Sharpness and Precision

    As the knife-making process progresses, the baton is passed from the blacksmith to the sharpener. The foundation of the blade, shaped by the blacksmith's powerful hands, is completed by the sharpener's delicate craft. This collaboration is truly a work of unity between the artisans, bringing out the final beauty and performance of the knife.

  • The Detailed Process of Sharpening and Its Significance

    The sharpening process, known as "togi", is the final step where life is breathed into the blade. This process consists of approximately 20 individual steps, carefully crafted to bring the knife closer to its finished form. Starting with a coarse whetstone and gradually progressing to finer ones, the knife undergoes a series of refinements. This multi-step process maximizes the blade's sharpness, beauty, and durability.

  • Furthermore, sharpening is done with cold water to prevent the rise in temperature, which could cause tarnishing or reduce the blade’s hardness. This cold-water sharpening process plays a vital role in preserving the quality and structure of the blade, ensuring it remains in peak condition.

  • Four Key Points That Demand the Craftsman's Skill and Precision

    The sharpening process focuses on the following four critical points:

  • 1. Eliminating Unevenness in Sharpening

    The rotating whetstone's surface must remain perfectly flat, with no wobbling. A skilled artisan’s sharpening appears almost still, achieving a flawless result.

  • 2. Beautifying the Shape of the Blade

    The knife’s shape and form are just as important as its sharpness. The sharpener ensures that the blade not only cuts well but also has an aesthetically pleasing and balanced appearance.

  • 3. Correcting Distortions or Bends

    Any distortions or bends that may arise during the sharpening process are carefully corrected to ensure the blade is in its optimal form.

  • 4. Paying Attention to Friction Heat

    Excess friction heat can cause "tempering" issues, weakening the blade’s hardness. The artisan must be extremely careful to avoid this, especially during polishing.

  • The Completion of the Knife — The Fusion of Tradition and Skill

    The sharpening process is not just a technical task; it is an art that shapes the soul of the blade. The expertise and passion of both the blacksmith and the sharpener result in knives that will be cherished for years. Through this intricate process, the knife is finished, becoming a beautifully crafted tool that delivers unparalleled sharpness and performance.

    The sharpener's skilled hands ensure that, even before the knife reaches the hands of a chef, it is in perfect condition, ready for the task at hand.

  • 1. Rough Grinding: Rough Grinding: The Foundation of Knife Craftsmanship

    In the world of knife making, rough grinding is a critical step that determines the shape and performance of a blade. This initial grinding process shapes the blade, reduces its thickness, and sets the groundwork for the precise finishing stages that follow.

    Rough grinding consists of the following stages:

  • 1. Blade Tip Grinding: Precision in Forming the Edge

    The blade is fixed onto a wooden platform and ground against a large, 1-meter-diameter cylindrical grindstone. At this stage, the tip of the blade is thinned to approximately 0.5 millimeters, forming the fundamental edge. This step demands not only technical accuracy but also aesthetic precision, ensuring the blade’s overall balance and elegant appearance.

  • 2. Full Surface Grinding: Ensuring Uniformity Across the Blade

    Beyond the blade tip, the flat surface and spine (back edge of the knife) are polished to achieve a consistent shape and balance throughout. Historically, traditional techniques such as “kurouchi” (blacksmith finish) left an oxidized layer on the blade's surface, providing additional rust resistance and durability. This detail reflects the ingenuity and cultural significance embedded in rough grinding.

  • 3. Distortion Correction: Enhancing Blade Precision

    Any distortions caused during the grinding process are carefully corrected using wooden tools or small hammers. This meticulous step ensures that the blade’s overall accuracy and functionality are optimized.

  • The Role of Rough Grinding and the Importance of Craftsmanship

    Rough grinding serves as the foundation of knife making, accounting for nearly 80% of the blade’s final form. The groundwork laid in this stage significantly influences the knife’s sharpness, durability, and overall performance. It’s not just about shaping metal; it’s a testament to the artisan’s expertise and dedication, requiring years of experience to master.

  • Even in modern times, the fusion of traditional techniques and innovative technologies continues to push the boundaries of knife craftsmanship. By understanding the crucial role of rough grinding, we can better appreciate the artistry and effort that go into creating each blade.

  • 2. Correcting Warp

  • During the grinding process, the frictional heat generated by the rotating grinding stone can cause the knife to warp. If this distortion is overlooked, it will prevent the blade from making uniform contact with the grinding stone, resulting in ineffective sharpening. Therefore, a crucial step in the crafting process is dedicated to correcting this warp.

    Craftsman's Insight: "When sharpening, temperatures can rise to between 300 and 400 degrees Celsius, causing the carefully tempered steel to lose its hardness. If the heat treatment is reversed, the steel softens significantly, rendering the blade ineffective."

  • 3. Hon-togi

    Hon-togi is a crucial process that gives the knife its true shape. During this stage, the entire knife is pressed against a rotating grindstone, first to flatten the surface and reduce its thickness. After that, the blade’s edge is carefully honed to enhance its sharpness.

  • Craftsman's Note: "Shinogi is the most challenging part of the process. When performing this task, I hold my breath while sharpening the knife."

    This stage determines the knife's final performance, requiring the craftsman's skilled technique and focused concentration.

  • 4. Back Sharpening

    Back sharpening is an essential step in the knife manufacturing process. In this stage, the back bevel created during the forging process is further thinned and shaped. The back bevel refers to the area on the reverse side of the blade, and its finishing significantly contributes to the knife's cutting performance.

  • By performing back sharpening, the thickness of the blade is properly adjusted, achieving a sharper cutting edge. This process requires skilled techniques, showcasing the craftsmanship of the knife artisans. A knife refined through back sharpening can greatly influence the outcome of the dish, maximizing its performance.

  • 5. Final Sharpening: Hand-Honing Techniques to Unlock Sakai Blades' Ultimate Sharpness

  • The final step of hand-finishing knives brings out their true potential. This meticulous process defines the sharpness and precision of Sakai blades, as each knife is individually assessed and refined to achieve its highest quality. It is a labor-intensive task that involves switching between different types of whetstones for each stage, requiring both time and dedication.

  • Ⅳ. Handle Attachment: Crafting Balance and Comfort for the Perfect Fit

    At the final stage of knife-making, particularly during the handle attachment, no shortcuts are taken. The meticulous attention to detail is what drives the creation of knives that can be used for many years.

  • "Sakai Knife Finishing: The Art of Handle Attachment and Its Attention to Detail"

  • Handle attachment is a crucial process in the final stage of knife-making, where the skilled craftsmanship and thoughtful care of artisans come into play. Metal ferrules, plastic components, and for high-end knives, water buffalo horn ferrules are used. The water buffalo horn ferrule is especially valued because it wears at a similar rate to wooden handles, maintaining a smooth and consistent feel over long-term use.

  • Handle Attachment

  • The part called the "nakago" (tang) is heated and then inserted into the handle. Using a wooden mallet, the tang is firmly secured within the handle. After correcting any distortions and ensuring the blade is perfectly straight, the Sakai forged knife is complete.

  • The tang is secured by expanding it with heat, making the handle attachment incredibly sturdy. This method enhances both safety and durability, allowing the knife to withstand long-term use and water contact without loosening. Natural wood is commonly used for the handle, ensuring stability and aesthetic appeal. Additionally, maintenance is straightforward: if the handle loosens, it can be easily re-secured. The material and shape of the handle add personality and can be customized to suit the user’s preferences.

  • This meticulous process creates the "ease of use" and "beauty" of Sakai knives, which are loved by chefs around the world.

  • The Evolution of Handle Making: The Fusion of Tradition and Modern Technology in Crafting a Knife

    The process of making a knife handle was once entirely done by hand, with the limit being 100 pieces produced per day. However, in modern times, the process has been mechanized, allowing for mass production. Despite this, each step still carries the wisdom and craftsmanship of tradition.

  • From selecting the wood to drying, shaping, drilling holes, beveling, and fitting the collar, every step is carried out with meticulous care. For example, the raw wood is cut with a large saw and naturally dried, which preserves the quality of the material. Additionally, the hole drilling and the smooth finish of the handle are accomplished through a combination of machinery and handcraft, ensuring the perfect balance between technology and tradition.

  • Particularly, the fitting of the collar (mouthpiece) involves using materials like buffalo horn or metal parts, focusing on both beauty and durability. The final polishing step is what gives the handle its smooth texture and elegant appearance.

  • By blending modern technology with traditional craftsmanship, the handle of a Sakai knife is not only beautiful to look at but also designed to feel perfect in hand, providing both aesthetic and functional excellence.

The Process of Making a Knife

The process of making a Japanese knife involves numerous steps and significant artisanal handiwork, taking one to two months per knife. The primary methods in Japan are traditional "forging," where steel is hammered and shaped, and "stamping," where blades are cut from steel sheets. These techniques, rooted in Japanese sword-making history, showcase rare technical prowess and high quality in knife manufacturing.

The Process of Making a Knife

The Process of Making Japanese Knives

Video Provided: ProcessX (YouTube)

The Origin of Craftsmanship

  • The quenching process requires absolute focus—even a single moment of carelessness can determine the sharpness of the blade.

  • Quenching is one of the most crucial steps in breathing life into swords and tools. Heating the steel in fire and cooling it at the exact right moment—this split-second decision profoundly impacts the sharpness and durability of the final product. Even for seasoned artisans, the tension in this moment never fades.

  • It demands not only technical skill but also a craftsman’s keen intuition and unwavering concentration. The slightest change in temperature or the subtle behavior of the steel must be observed and judged precisely. Each attempt is unique, and no matter how many times we repeat this process, there is no room for compromise.

  • When someone holds a finely sharpened tool and feels its precision, or when they cherish it for years to come, that is the reward we strive for as craftsmen. We pour our hearts into ensuring that each tool serves its purpose flawlessly, imagining the impact it will have on someone’s daily life or work.

  • Quenching is where the “soul of craftsmanship” is truly tested. It is for this reason that we approach every single piece with the utmost seriousness and dedication.
Sakai Traditional Craftsmen Collection

KIREAJI's Three Promises to You

  • japanese_knife_made_in_Sakai

    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.

  • Honbazuke

    2. Genuine Sharpness

    We offer free Honbazuke sharpening performed by skilled craftsmen, ensuring that you experience the authentic sharpness of a true Sakai knife.

  • 3. Lifetime Knife Use

    Each knife comes with a free Saya (protective sheath) for added durability. We also offer after-sales service through a trusted Sakai City workshop to maintain your knife's performance.