Japanese Knife Glossary
"Ever wondered, 'What does this mean?' or thought, 'This is different from what I knew'?" On this page, we will introduce technical terms used in the knife industry, covering both terms that have appeared in our blog so far and those that have not yet been featured.
We hope to assist our customers by providing them with a glossary of knife terms, enabling them to deepen their understanding of specialized knife terminology and enjoy cooking even more.
A
Abrasive grains
It refers to the hard particles used in grinding wheels for polishing. In the case of synthetic grinding wheels, materials such as carborundum, green carborundum, and white arundum (often referred to as C, GC, and WA, respectively) are used. Each of these materials has its own hardness and resistance to grinding, resulting in differences in grinding power, depth of scratches on knives, etc. Natural grinding stones are made from the remains of plankton called radiolaria. Compared to artificial whetstones, natural whetstones are less angular, so they are less likely to scratch knives and produce a clean finish on the knife blade after sharpening.
Related websites
Expert Knife Sharpening Service | KIREAJI
Mastering Japanese Knife Sharpening: Techniques & Tips | KIREAJI
Aburayaki
One of the heat treating methods for Japanese knives, which uses oil to cool down the heated blade. Compared to quenching in water, the temperature decreases more gradually, which enables a relatively stable heat treatment without the risk of the blade cracking.
Related websites
White Steel#2 (Honyaki- Aburayaki) – KIREAJI
The Art of Making Japanese Knives: Detailed Process | KIREAJI
Aike
Aike is a specific type of error that can occur during the manufacturing process of traditional Japanese knives. Specifically, it refers to gaps or defects that appear on the blade's surface (hamon), often visible as black lines or small holes resembling black sesame seeds. This phenomenon arises during the joining of hagane (steel) and soft iron, and it is often an unavoidable aspect of knife production.
Annealing -Yaki-namashi-
Cooling methods adjusted according to the material processing are devised in this process. This is a heat treatment method that makes materials uniform as well as easy to process. This process is used to soften the blade and remove internal strain from the steel.
Related websites
The Art of Making Japanese Knives: Detailed Process | KIREAJI
Artificial whetstone
In contrast to natural grinding wheels, which are formed over a long period of time by sedimentation, synthetic grinding wheels are made by hardening abrasive grains and a binder through artificial processes such as baking and drying. While most natural grinding stones are expensive, especially for finishing wheels, artificial grinding stones are relatively inexpensive and can be made homogeneous throughout. There are a wide variety of artificial grinding wheels with varying degrees of hardness and grinding power, depending on the combination of abrasive grains, bonding agents, and manufacturing methods.
Related websites
Expert Knife Sharpening Service | KIREAJI
Mastering Japanese Knife Sharpening: Techniques & Tips | KIREAJI
Awase
<Honyaki, Awase>
- When looking at the materials used in kitchen knives, there are two types of knives: “Honyaki" or “All steel" knives, both of which are made from a single steel material in their construction. There is also “Awase" knives, which are made by combining two different materials such as steel and soft iron.
- Structure of Japanese Knife
Among Japanese knives such as Yanagi and Deba knives, the most widely used type of knife is a laminated kitchen knife.
The combined knives use hard steel for the blade, and soft iron for the other parts of the knife.
Compared to knives made of a single piece of steel, these knives are stronger, harder to break, and easier to sharpen than those made of a single piece of steel. It is also called "Kasumi" (haze sharpening) because the soft iron portion appears hazy. On the other hand, Japanese knives made from a single piece of steel are called “Honyaki”. Honyaki is a high-end product that takes a lot of time and effort to produce. It is hard and does not warp or distort even if used for a long time.
Related websites
Single vs. Double-Edged Japanese Knives: A Comparative Guide | KIREAJI
AUS8
It is one of the stainless steel knives developed by Aichi Steel and is said to account for the majority of stainless steel knives on the market. It is a steel material with improved hardness, toughness, and abrasion resistance. It is well balanced in terms of hardness, price, and corrosion resistance, and is best known as a steel for Western-style kitchen knives for home use because of its ease of use, but it is also considered a relatively inexpensive and readily available steel for those looking for a stainless steel kitchen knife for professional use. In addition, knife makers often refer to knives made of this steel as "molybdenum pot" or "molybdenum vanadium steel" when selling them, but these are not the official names. AUS-8 is the most common steel produced by Aichi Steel, but there is also AUS-6, which is less expensive and has a lower hardness, and AUS-10, which is more expensive and has a higher hardness.
B
Back plow -Urasuki-
This is one of the processes applied to the back of Japanese knives, and refers to the indentation on the back of the knife. By making the indentation, the area where the food comes in contact with the knife is reduced, which in turn reduces friction and improves the sharpness of the knife.
Related websites
Decoding Japanese Knives: Understanding Parts and Names | KIREAJI
Enhancing Japanese Knife Functionality with Urasuki Dimples | KIREAJI
Blade length -Hawatari-
It refers to the entire surface of the knife. For knives without a girth, the blade length is from the chin to the cutting edge, and for knives with a girth, the blade length is from the girth to the cutting edge.
Related websites
Decoding Japanese Knives: Understanding Parts and Names | KIREAJI
Blade line -Hasen-
The name of the part of a knife that refers to the line traced by the tip of the blade. Depending on whether the line of the blade is straight or curved, it is suitable for different foods and tasks. Whatever the line, if the blade line is distorted, it will not make perfect contact with the cutting board, making it impossible to cut the way you want. Whether or not the blade line is not distorted is one of the factors that determine whether a knife is good or bad.
Related websites
Decoding Japanese Knives: Understanding Parts and Names | KIREAJI
Blade metal
It refers to the hard metal portion of the metal that makes up the laminated knife, which is used to cut the food. The sharpness and its durability vary greatly depending on the metal material of this blade metal.
Related websites
Japanese Knife Materials: Carbon Steel vs. Stainless Steel | KIREAJI
Decoding Japanese Knives: Understanding Parts and Names | KIREAJI
Blue Steel -Aoko,Aogami-
Also known as "Aogami", this is a low-alloy steel that adds chrome and tungsten (super hard alloy) to white 2 steel. It is a steel material used by many professional chefs for knives with a sharp edge, which is difficult to wear and maintains sharpness for a long time. It has a good resilience, making it less likely to chip compared to white steel. Depending on the carbon content, there are Aogami #1 and Aogami #2. [Aogami #1] is what you get when you add carbon to Aogami #2. It is extremely hard and, like white 1 steel, is expensive and has rarity value. It is difficult to sharpen, so it is suitable for veterans. [Aogami #2] is highly regarded by chefs for its stable sharpness and good edge retention.
< Blue Steel & White Steel >
Difference between Blue Steel and White Steel
Blue steel is an alloy carbon steel in which alloying elements are added to white steel to improve sharpness and durability. Therefore, blue steel has advantages over white steel, such as being "chip-proof" and "sharpen-proof. The price of knives made of blue steel is also higher because of the higher cost of raw materials.
Advantages |
Disadvantages |
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Blue |
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White |
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Difference between #1 and #2 in carbon steel type
The amount of carbon contained varies, with #1 and #2 being the most abundant in that order. The more carbon is contained, the harder the material is and the longer the sharpness lasts. However, it is also easier to chip.
Related websites
Understanding Carbon Steel in Japanese Knives | KIREAJI
Bullion -Digane-
Of the metals that make up a laminated knife, this refers to the soft metal that is sandwiched between the hard metal. The presence of the base metal increases the overall durability of the knife because the softer metal absorbs the impact transmitted from the cutting edge.
Related websites
The Art of Making Japanese Knives: Detailed Process | KIREAJI
Japanese Knife Structures: Single-Edged vs. Double-Edged | KIREAJI
Bunka Houtyo
Bunka Houtyo are all-purpose household knives that became popular in Japan some time ago. It is characterized by the shape of its blade, which is almost rectangular in shape and cut off at an angle, called a "naikiri" (vegetable cutting) knife. There is no particular difference from Santoku Houtyo. The origin of Bunka Houtyo is that it was created when Western food culture was introduced to Japan.
Bunka means cluture.
C
Camellia oil
Camellia oil is extracted from the seeds of camellia, and is often used as an anti-rust oil for kitchen knives and other tools. Rust-preventive oil is intended to prevent corrosion by coating the surface of metal during storage, but if the oil itself becomes oxidized, this will cause corrosion. Camellia oil contains high oleic acid and is not easily oxidized, making it a suitable rust-preventive oil.
Related websites
How to Prevent Rust on Japanese Knives | KIREAJI
Essential Japanese Knife Care Tips for Durability | KIREAJI
Carbon
An essential element for steel, it forms compounds with various elements and is a typical element for increasing hardness and strength, It is a typical element for increasing hardness and strength by forming compounds with various elements.
Related websites
KIREAJI: The main elements used in knife steel.
Carbon Steel
Generally, the word "steel" in kitchen knife materials refers to carbon steel, which is made by blending iron with carbon and other materials. The higher the carbon content in iron, the harder it becomes, and the more sharpness and long-lasting sharpness it has. Because carbon steel contains more carbon, it is harder and cuts better than other materials such as stainless steel. It also has the advantage of being easy to sharpen. On the other hand, it has the disadvantage that it easily rusts due to water and food debris, and requires frequent maintenance. Another disadvantage is that as hardness increases, toughness decreases, making them prone to chipping. Carbon steel is a material for advanced cooks who pursue sharpness and are able to properly care for their tools.
< Japanese knife material (Carbon steel, Stainless steel) >
- “Carbon steel" and “Stainless steel" are the main materials used for knives
- “Carbon steel" is defined as having 0.04-2.14% carbon content of the five elements of iron. As carbon content increases, the material becomes harder. Cast iron is also used for car parts. Adding more than 10.5% chromium to carbon steel makes it "stainless steel". The addition of chromium improves rust resistance.
Related websites
Understanding Carbon Steel in Japanese Knives | KIREAJI
Casting
Casting is a processing method of melting metal into a liquid and pouring it into a mold.
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Ceramic knife
Chin -Ago-
The part of a kitchen knife near the handle-end of the cutting edge. It is sometimes used to scoop out small parts of ingredients, such as removing the eyes from a potato.
Related websites
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Chinese knife
It is a type of kitchen knife and is an all purpose knife used in Chinese knife cooking. This knife is characterized by a wide rectangular shape with a slightly curved blade line. It can be used not only for cooking meat, fish, and vegetables, but also for cutting bones and crushing them using the back side. Utilizing its shape and weight, it is possible to do a variety of cooking, from delicate dishes to vigorous tasks. They are numbered according to their thickness and weight, so you can choose the one that suits your purpose and preference.
Chisel holder -Tagane-ire-
This refers to the process of engraving a name or inscription on a kitchen knife. As the name implies, a flat metal bar with a flat cross section called a tagane is used to engrave lines on the blade of the knife to express characters and other information.
Chromium
Improves quenching properties.
Stainless steel contains at least 10.5% Cromium.
Related websites
Japanese Knife Materials: Carbon Steel vs. Stainless Steel | KIREAJI
Clam blade -Hamaguriba-
This term describes the shape of the cutting edge, which is smooth and rounded without stepped edges. Since the tip of the blade is at an obtuse angle, it is less sharp, but has the advantage of being less prone to chipping.
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Expert Knife Sharpening Service | KIREAJI
Mastering Japanese Knife Sharpening: Techniques & Tips | KIREAJI
Cobalt
Related websites
Japanese Knife Materials: Carbon Steel vs. Stainless Steel | KIREAJI
Core -Nakako-
This is the name of the part of a Japanese knife, and refers to the part of the blade that is inside the handle.
Related websites
Decoding Japanese Knives: Understanding Parts and Names | KIREAJI
Correction whetstone
These wheels are used for surface preparation of grinding wheels. Some are made of abrasive grains and an adhesive, as is the case with ordinary artificial wheels, while others are made of abrasive grains adhered to a metal plate by electrodeposition. It is necessary to select the appropriate type of grinding wheel according to the number and hardness of the wheel to be repaired.
Related websites
Mastering Japanese Knife Sharpening: Techniques & Tips | KIREAJI
Corrosion Resistance
Corrosion resistance refers to the resistance to rust. Rust-resistant knives, such as stainless-steel knives, are easier to clean and handle.
<Japanese Knife Materials 4 points>
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Japanese Knife Materials: 4 Key Characteristics Explained | KIREAJI
D
Damascus Steel
Mainly used for Western-style knives. Ancient Damascus steel was a type of steel made in India since ancient times, known as "wootz steel" in Europe. The manufacturing process at the time was shrouded in mystery and has yet to be fully understood. Today's Damascus steel is a type of steel that imitates the performance and appearance of this ancient Damascus steel (wootz steel). It is a forged steel made by layering different metals to create an artificially patterned design, characterized by a wavy pattern.
Its features include:
-Beautiful pattern: Damascus steel creates patterns by layering or folding different types of steel. This creates a beautiful pattern throughout the blade, resulting in a beautiful and luxurious finish.
-High hardness: Because Damascus steel is forged by layering different types of steel, its hardness is increased. Additionally, layering creates a fine crystalline structure inside the blade, further enhancing its strength.
-Sharpness: Damascus steel has high hardness, making it easy to maintain a sharp edge and prolonging its sharpness. Additionally, the fine crystalline structure allows for a sharp edge and makes it easy to cut even slippery materials.
-Durability: The layering of Damascus steel enhances its strength and durability. The forging process also removes impurities and air bubbles from inside the steel, resulting in fewer defects and making it highly resistant to wear and corrosion.
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Discover the Elegance of Damascus Steel Knives | KIREAJI
Deba
Deba features a thicker blade and a sharp, thin cutting edge. When cooking fish, you can use this knife to remove the head of fish and for grating the fish.
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Dimple Processing
Dimpling is a processing method often used for Western kitchen knives, in which the cutting edge of a Japanese knife is uneven. Similarly, there is the perforated finish, where multiple holes are made in the cutting edge, but it is considered to lack durability and is not used very often in the professional field. The purpose of both methods is to reduce the area of contact between the food and the knife and to prevent the food from sticking to the knife. When sharpening, both the front and back of the knife must be sharpened in the same manner.
Double-edged blade
A double-edged knife is a knife structure characterized by a symmetrical blade attachment as opposed to a single-edged knife structure in which the blade is attached to only one side of the blade when viewed from the center of the cutting edge.
This structure is often used in Western-style kitchen knives. Since the blade is symmetrically attached to the left and right sides, it is possible to cut food straight without much awareness. Also, as with single-edged knives, there is no difference depending on the dominant hand, and they can be used by left-handed and right-handed people alike.
<Western knife / Japanese knife>
The main difference between Western and Japanese knife is that Western knife is double-edged, while Japanese knife is based on single-edged blades. The reason why many Japanese knife has single-edged blades is because when the material is cut off, the tip of the blade cuts slightly to the left, which makes it easier for the cutter to separate from the material, allowing for a quick chopping motion. Since the cut can be made without destroying the structure of the material cross section, a beautiful cut surface can be obtained. Also, the single-edged blade has a thinner and sharper cutting edge compared to the double-edged blade.
Related websites
Single vs. Double-Edged Japanese Knives: A Comparative Guide | KIREAJI
Japanese Knife vs. Western Knife: Features and Differences | KIREAJI
E
Ebony
Ebony is a wood often used for kitchen knife handles. It is black in color, has a dense heartwood, and is used as a high-grade wood. Because of its high density, ebony excels in terms of solidity, durability, and water resistance. In addition to such performance, the black color and texture of ebony wood also give it an excellent design, and it has earned a high position among kitchen knife handles.
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Edge -Hasaki-
The tip of the blade of a Japanese knife. The sharpness and durability of the knife can vary depending on the shape and thickness of the tip.
Related websites
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Estuke
One of the processes in knife making, which refers to the work of attaching a handle to a knife. It is often done as the final step after sharpening the knife. In the case of Japanese knives, the blade portion of the tang that is inside the handle is heated and inserted into the handle.
Related websites
The Art of Making Japanese Knives: Detailed Process | KIREAJI
F
Face up -Mennaoshi-
It refers to the process of straightening and correcting a distorted whetstone. As the knife is sharpened using a whetstone, the surface of the whetstone becomes dented or distorted. If you use a whetstone in such a state, you will not be able to sharpen the knife as you wish, and the line of the blade will be distorted. Therefore, it is necessary to keep the surface of the whetstone level by using a correcting whetstone to correct the surface.
Related websites
Mastering Japanese Knife Sharpening: Techniques & Tips | KIREAJI
Ferrule -Kuchigane-
The metal part that connects the handle to the blade. It reinforces the connection between the handle and the blade, while also preventing water and dirt from entering the handle.
Related websites
Decoding Japanese Knives: Understanding Parts and Names | KIREAJI
Finishing whetstone
It is one of the three types of grinding stones, the finest of which is used mainly for finishing work to clean up the appearance. In terms of synthetic whetstones, it generally refers to those with a grit size of #3000~. Because of its fine grain, the grinding and polishing power is low, but the scratches on the metal are shallow, resulting in a clean finish.
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Flat -Hira-
The flat part of a Japanese kitchen knife between the blade grind and the tip. It is sometimes used for tasks such as crushing garlic.
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Decoding Japanese Knives: Understanding Parts and Names | KIREAJI
Forge welding
It is a process in the manufacturing of Japanese knives where the jigane (soft iron) and hagane (hard steel) are joined together by heat and pressure from hammering the metals. By adding a layer of powdered refractory material such as feldspar onto the heated jigane to prevent the formation of oxide, the hagane is then placed on top and hammered to join the two metals together.
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Forging
This refers to a metalworking technique in which metal is hammered to shape it into the desired form. Many traditional Japanese knives are made using this technique. By hammering the metal, air and impurities are removed from it and the metal's grain structure is made consistent. As a result, the metal can be "tempered" to become harder and more resistant to impact.
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Friction Resistance
High friction resistance prolongs the life of a cutting edge. It reduces the frequency of knife resharpening. In general, the higher the hardness, the more resistant a knife is to wear. It also depends on the content of additives such as carbon and chromium.
<Japanese Knife Materials 4 points>
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Japanese Knife Materials: 4 Key Characteristics Explained | KIREAJI
G
Garasaki
Garasaki is a useful knife for cutting up chickens. It is wide, thick, and sturdy, making it perfect for the task. It can also chop through cartilage and be used to crack open shells like those of lobsters.
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Ginsan
Produced by Hitachi Metals, it is a high-carbon version of the silver paper #1, with a hardness of 59-61, which is comparable to that of carbon steel, and has a sharp cutting edge. It has been widely used for many years as a rust-resistant Japanese kitchen knife.
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Ginsan Japanese Knives: Rust-Resistant Elegance | KIREAJI
Grinding wheel for surface repair
To correct the surface of the whetstone, use a correcting whetstone.1 Soak the correcting whetstone in water and place it on top of the worn medium whetstone. When the surface of the medium whetstone is flattened, wash the correcting whetstone and medium whetstone in water and hang them to dry in the shade.
Gusset -Machi-
This is the name of a part of a Japanese kitchen knife, and refers to the step at the upper end of the blade. Not all kitchen knives have this step, but it is found on sashimi knives, vegetable cutting knives, etc.
Related websites
Decoding Japanese Knives: Understanding Parts and Names | KIREAJI
Gyuto
This all-purpose knife can be used for meat, fish, vegetables, and anything else.
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H
Hammer
A basic tool of blacksmiths used to shape red-hot iron by striking it.
Hammered Finish
Hammoku is a method of finishing knives by leaving hammer marks on the flat part of the knife to give the surface a four-convex finish. This finish is mainly used on Gyuto, Santoku and Nana-kiri knives. The advantage of the hammered finish is that it reduces the contact area between the food and the knife when cutting, so there is less resistance and the food is less likely to stick to the surface of the knife, but in reality the effect is not that great. It can be said that this finish is more design than function.
Handle
It is the name of a part of a kitchen knife and refers to the bar-shaped handle provided for holding the knife. The way of attachment and form differ between Japanese and Western kitchen knives. Japanese kitchen knives are attached to a wooden handle by inserting the core of the knife into the handle. The handle of a Japanese knife is easily removable for easy repair.
Related websites
Japanese Knife Handles Guide | KIREAJI
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Hardness
Hardness is one of the most important indicators in the selection of knife materials. Since the sharpness of a knife is affected by the performance of the cutting edge, it cannot be said that a higher hardness of the material will result in a better sharpness. However, it is a point of the element that influences the sharpness of a knife.
However, there is a disadvantage in that the higher the hardness, the more the toughness is compromised and the more likely the knife is to spill. It is also more difficult to sharpen knives. The hardness of a knife is expressed by a numerical value called HRC, and the higher the value, the harder the knife.
<Japanese Knife Materials 4 points>
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Japanese Knife Materials: 4 Key Characteristics Explained | KIREAJI
Haze -Kasumi-
It is a term used as an alias for AWASE. It is derived from the fact that during the finishing process of AWASE, the core material is given a glossy finish while the outer layer of the blade is often finished with a mottled pattern to create a "Kasumi" effect.
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Heat Treatment
A general term for processes that involve heating, cooling, and tempering. These processes impart hardness, toughness, wear resistance, and corrosion resistance to metals and are essential in blade making. Some special alloy steels do not require heat treatment.
Heel -Hamoto-
The part of a Japanese knife near the handle-end of the cutting edge. It is sometimes used for tasks such as peeling vegetables or cutting through bones with a Deba.
Related websites
Decoding Japanese Knives: Understanding Parts and Names | KIREAJI
Honbazuke
A highly skilled craftsman will perform the main blade attachment, so you can use the knife immediately from the day you receive it.
Related websites
Honbazuke: What is Honbazuke method? ”The knife is not yet finished." – KIREAJI
Honyaki
<Honyaki, Awase>
- When looking at the materials used in kitchen knives, there are two types of knives: “Honyaki" or “All steel" knives, both of which are made from a single steel material in their construction. There is also “Awase" knives, which are made by combining two different materials such as steel and soft iron.
- Structure of Japanese Knife
Among Japanese knives such as Yanagi and Deba knives, the most widely used type of knife is a laminated kitchen knife.
The combined knives use hard steel for the blade, and soft iron for the other parts of the knife.
Compared to knives made of a single piece of steel, these knives are stronger, harder to break, and easier to sharpen than those made of a single piece of steel. It is also called "Kasumi" (haze sharpening) because the soft iron portion appears hazy. On the other hand, Japanese knives made from a single piece of steel are called “Honyaki”. Honyaki is a high-end product that takes a lot of time and effort to produce. It is hard and does not warp or distort even if used for a long time.
Related websites
Honyaki Knives: The Zenith of Japanese Craftsmanship | KIREAJI
HRC
The HRC of Japanese kitchen knives is a unit that represents hardness and is commonly used in the Japanese cutlery industry. HRC stands for "Rockwell Hardness Scale" and is a scale used to measure the hardness of cutlery.
The HRC of Japanese kitchen knives typically ranges from 57 to 62. This varies depending on the type of steel, forging technique, heat treatment method, and other factors used to make the knife blade. Generally, the higher the HRC value, the harder the blade, resulting in better sharpness, but it may also lead to lower strength.
The HRC value of Japanese kitchen knives is determined by measuring the hardness when pressure is applied to the blade tip. A dedicated Rockwell hardness tester is used for this measurement. The tester applies a specified load to the blade tip and measures the depth, which is used to calculate the HRC value.
Related websites
Japanese Knife Materials: 4 Key Characteristics Explained | KIREAJI
J
Japanese knife
A type of kitchen knife traditionally used in Japan. It often has a single-edged blade structure, and the handle is often made of wood such as magnolia or ebony. While most Western kitchen knives are all-purpose knives that can be used for all kinds of foods with a single knife, Japanese kitchen knives are characterized by the specialization of various types of knives according to their ingredients and uses.
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Jigane (Base Steel)
The basic low-carbon steel used to form the shape of tools. In traditional Japanese knives, "awase" (laminated) construction involves forge-welding steel onto a portion of jigane. It typically consists of very soft steel with a carbon content of 0.15% or less.
K
Kamausuba
A Kansai-shaped knife with a sickle-shaped tip for cutting vegetables. The cutting edge is thin and the blade is straight. It is also used for stripping katsura.
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Kanashiki (Anvil)
Also known as a forge's anvil, it is a blacksmith's forging workbench. Traditionally, it was made by forge-welding steel onto the surface of wrought iron.
Kasumi
It is a forged knife. This is the most common type. The back is steel and the front is base metal, joined together front and back. For this reason, you can see a line on the blade (cutting edge) part. This line is the boundary between steel and base metal. The pattern of this line also changes depending on the forging method and the type of steel.
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Kasumi Hari Awase
The back is steel and the front is base metal, joined together front and back, but in this case, they use steel material that is already made in two layers. Usually there is no edge in forged knives. Therefore, the sharpness is lower than Kasumi(Aawase). The feature is that the thickness is uniform and the line on the blade (cutting edge) part is straight. It is often used for yanagiba knives. The price is also a little cheaper. Of course, the sharpness and price vary greatly depending on the material.
Related websites
Single vs. Double-Edged Japanese Knives: A Comparative Guide | KIREAJI
KIREAJI
KIREAJI means Sharpness in English.
We aim to convey the joy of cutting simply in life. It is said that humans are made from the food we eat, but did you know that what we eat, how we eat it, and the emotions we feel while eating can all affect our bodies? By cutting ingredients with a well-sharpened knife, we can create wonderful dishes without damaging the fibers.
When enjoying a delicious meal, people are said to feel no anger or anxiety. We believe that through this joy of cutting, we can open up a brighter future. KIREAJI was established to convey the joy of "cutting" in life.
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Kitaeji (Forged Steel)
A type of wrought iron made by repeatedly forging and folding multiple pieces of iron with different carbon contents, creating a wavy pattern.
Kuro-uchi
This is one of the finishing methods for kitchen knives. Normally, knives are hardened during the manufacturing process, which forms an oxide film on the surface and turns it black. Polishing to remove this oxide film is called "polishing", while polishing only the blade and leaving the black film on the flat part is called "kuro-uchi". Since the manufacturing process of kuro-uchi is shorter than that of polishing, the price is often reduced accordingly. It also has the advantage of being rust resistant.
M
Manganese
Element that makes quenching easier and increases tenacity.
Related websites
The Art of Making Japanese Knives: Detailed Process | KIREAJI
Magnolia obovata
A type of wood often used to make handles for Japanese kitchen knives. It is characterized by its almost white appearance. It is used as a wood for various products, including kitchen knives and Japanese sword handles, because it is relatively uniform, has little variation in quality, and is easy to process.
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Japanese Knife Handles Guide | KIREAJI
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Medium Whestone
Among the three types of whetstones, the fineness of grindstone is medium. In the case of synthetic whetstones, the #400-2000 grade is often used. After grinding the blade extensively with a rough grindstone, a medium grindstone can be used to make deep scratches on the blade shallower and the surface smoother. The medium grit is also fine enough to produce a sufficient sharpness even if sharpening is completed with only this medium grit, unless the shape of the blade needs to be drastically deformed, such as for repairing a chip.
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Mirror Polished
This is one of the finishing processes applied to the blade of a kitchen knife, in which the surface of the blade is polished until it looks like a mirror. The blade is carefully polished with a fine grindstone to create a mirror-like surface.
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Mizuyaki
One of the quenching methods for Japanese kitchen knives, which uses water to cool down the heated blade. In contrast to "ABURAYAKI" where oil is used, this method rapidly lowers the temperature of the metal. It often causes distortion or cracking due to the drastic temperature change, which tests the skill of the craftsman, but results in a tightly compressed and hard metal.
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Molybdenum
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Mukimono
This knife is often used for stripping katsura. The Usuba is thinner than the thin blade.
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Muzzle
Of the metals that make up a laminated knife, this refers to the soft metal that is sandwiched between the hard metal. The presence of the base metal increases the overall durability of the knife because the softer metal absorbs the impact transmitted from the cutting edge.
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N
Nakakojiri
This is the name of a part of a Japanese knife, and refers to the end of the middle part of the knife.
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Nakiri Knife
A type of kitchen knife, it is mainly suitable for cooking vegetables. It often has a double-edged blade structure, and is characterized by a rectangular blade with a small warped edge line. The moderately straight blade line enables smooth chopping of vegetables.
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Name engraving
A craftsman will engrave your name on the knife with all his heart. It will be a one-of-a-kind, personalized knife.
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Natural whestone
These whetstones are created by grinding naturally formed stones over hundreds of millions of years.
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Nihonkou
This is pure carbon steel (Japanese steel) with reduced impurities. Although it is less pure than white steel, it is relatively inexpensive. It is hard to chip and has the sharpness and sharpenability of carbon steel, making it an easy-to-handle steel for processing plants and home use.
O
Octagonal pattern
One type of Japanese knife handle with an octagonal cross section. The many corners make it easy to hold and also make the handle non-slippery.
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Oxidized film
It is an extremely thin film of oxide that forms to cover the surface of metal. As stable oxide covers the metal, it acts as a barrier between the metal and the air, preventing oxidation of the metal. Stainless steel utilizes this oxide film to prevent rusting of the metal.
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P
Patterning (E-tsuke)
The "handle" is attached to the completed body of the knife. The handle is attached to the grip of the knife body called "Nakago" by caulking the handle made of a material that is resistant to water and other corrosive substances.
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Petty
This small knife is useful for cutting fruits and simple cooking.
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Phosphorus
This element is harmful to steel and has an undesirable property of cold brittleness, i.e., it makes the steel brittle when cold.
The content should be as low as possible.
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Power Hammer
Records show that water-powered hammers were made in Japan as early as 670 AD. In Europe, water-powered hammers came into use in the 13th century. By the late 18th century, steam-powered drop hammers were developed in France, and by the late 19th century, small foot-powered spring hammers were created. Large power hammers were introduced to Japan during the late Edo period. It was much later that they became common among general blacksmiths. Some blacksmiths did not adopt power hammers until recently.
Push back -Uraoshi-
This is one of the processes applied to the back of Japanese knives, and refers to the process of flattening the hollowed-out back edge of the overall back surface by Urasuki. By making both edges horizontal across the indentations, the food can be cut straight through.
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R
Rosewood -Shitan-
A red-black, sturdy, and lightweight wood that is popular among foreign users.
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Rough whetstone
Of the three types of whetstone, the coarsest are those used mainly in the shaping process, which is the first step in sharpening. In the case of synthetic whetstones, it often refers to those with a grit size of #320 to #800. Due to the coarseness of the grindstone, scratches on knives are deep and the grinding power is high. Therefore, it is used when the shape of a kitchen knife is greatly deformed, for example, when repairing a scratch or a distortion.
Rough shaping
Striking the knife with a belt hammer after removing the oxide film
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Rust
It refers to the red or black corrosion that often occurs on the surface of metals. The oxide or other compounds formed by the oxidation-reduction reaction of unstable atoms on the metal surface with oxygen or water are the substances that cause rust. In particular, if a steel knife is not properly maintained, rust can occur on its surface. Although small amounts of rust on a knife are not harmful to the human body, it can affect the taste and odor of food, and can therefore affect the quality of cooking. Therefore, frequent maintenance is necessary when using knives made of rust-prone steel.
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S
Sakai City
Sakai City is famous as a production area of Japanese knives, and many craftsmen continue to make traditional Japanese knives using their traditional techniques. Therefore, Sakai City's Japanese knives have earned high praise from professional chefs around the world. In fact, it is said that over 90% of professional chefs use Sakai City's Japanese knives and they have gained the trust of many chefs due to their sharpness and ease of use. Sakai City's Japanese knives are also used in high-end restaurants and cooking schools around the world, and their high quality is widely known.
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Sanjyo Citiy
It began with agricultural tools, and the expertise was later incorporated into blade crafting. Renowned for its superior forging techniques, the region is known for producing durable blades that can withstand long-term use, boasting high durability.
Sanjo flourished as a production center of steel kitchen knives and a major production center of stainless steel kitchen knives known for "Tojiro" and other products. Many manufacturers have an integrated production system with no division of production processes. As a result, craftsmen often have the skills to do everything from forging to metallurgy. It is very reassuring to know that all needs and defects can be handled by a single company.
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Santoku Houtyo
Saya
This wooden knife cover is designed to prevent the blade from damaging its surroundings when carrying a kitchen knife. It also protects from moisture and water and prevents the blade from rusting.
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Seki City
Known as one of the "Three Great Cutlery Capitals of the World," the blade-making region of Seki gained worldwide fame, with swordsmithing being particularly renowned. It is said that the culture of kitchen knives prospered due to this reputation, and Seki knives are well-known for their robust cores. Especially, many may have heard of Seki knives under the name of the renowned craftsman Magoroku Kanemoto II (Seki no Magoroku), who is celebrated as a master. In contrast to Sakai and Sanjo, which specialize in forged blades, Seki distinguishes itself by employing a press method in knife production.
Turning to mechanization, mass production systems became a major feature, and mass production for overseas markets began. At the same time, this area is actively engaged in technological innovation to improve quality.
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Sharpening
It refers to the process of sharpening and maintaining the sharpness of a cutting edge tool. By using sharpening stones, sharpeners, and other tools, the cutting edge is ground and polished near the edge to alter its shape and surface appearance. Through this sharpening process, the cutting edge tool becomes sharper and more visually appealing.
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Shinogi
The part of a Japanese knife where the cutting edge and the flat side meet, typically forming a straight line. It is often referred to as the edge line or blade road.
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Silicon
Element that increases hardness strength.
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Single-edged blade
It refers to the structure of a kitchen knife characterized by having the blade attached to only one side, as opposed to a double-edged kitchen knife, which has the blade attached symmetrically on the axis of the cutting edge. This structure is mainly used in Japanese knives. The bladed side has a flat, shinogi, or kiribei blade. Thereby, single-edged knives are thicker on the side of the peak and thinner on the side of the cutting edge. The unground side of the knife has an indentation called "ura-suki" and a process called "ura-oshi" (back-pressing). These processes reduce the area in contact with the food while maintaining a straight line from the tip of the blade to the peak. These structures enable single-edged knives to achieve high sharpness.
<Western knife / Japanese knife>
The main difference between Western and Japanese knife is that Western knife is double-edged, while Japanese knife is based on single-edged blades. The reason why many Japanese knife has single-edged blades is because when the material is cut off, the tip of the blade cuts slightly to the left, which makes it easier for the cutter to separate from the material, allowing for a quick chopping motion. Since the cut can be made without destroying the structure of the material cross section, a beautiful cut surface can be obtained. Also, the single-edged blade has a thinner and sharper cutting edge compared to the double-edged blade.
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SK material
Relatively inexpensive knives often use SK material, which contains slightly more impurities. The impurities referred to here are sulfur and phosphorus, among others. The higher the amount of these impurities, the easier it is to perform the "hardening" process, one of the steps in knife manufacturing. As a result, the skill required from the blacksmith is not as high. Additionally, these impurities can also cause embrittlement, which makes the metal lose its toughness and become more prone to breaking. For these reasons, SK material allows for cheaper production. Besides knives, SK material is also used for tools like axes, hammers, and saws.
Small blade -Koba-
This term refers to a blade with an angled structure toward the tip of the blade. The main purpose is to prevent chipping by making the cutting edge obtuse while maintaining the overall thinness of the cutting edge. A blade that is even thinner than this small blade is called an ito-ba (ito blade).
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Spine -Mine-
The opposite side of the blade from the cutting edge on a kitchen knife. It is sometimes used for tasks such as pounding meat.
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Stainless Steel
Stainless steel is an alloy made by adding chromium to increase resistance to rust, which is a major drawback of steel. Although generally inferior to steel in terms of sharpness, stainless steel is not only rust-resistant, but is also strong and chip-resistant, and sharpness lasts longer without frequent sharpening. It is attractive because it is easy to handle and does not require much care. There is a wide range of stainless steel materials, from reasonable ones to high-end ones, and some of them are as hard as steel and are easy to handle and sharp at the same time.
< Japanese knife material (Carbon steel, Stainless steel) >
- “Carbon steel" and “Stainless steel" are the main materials used for knives
- “Carbon steel" is defined as having 0.02-2.14% carbon content of the five elements of iron. As carbon content increases, the material becomes harder. Cast iron is also used for car parts. Adding more than 10.5% chromium to carbon steel makes it "stainless steel". The addition of chromium improves rust resistance.
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Stamping
Stamping is suitable for mass production of industrial products. A flat steel plate is placed on a die with a hole in it, and an upper die (punch) with the same shape as the hole is pressed on top of the plate to apply strong pressure to punch it out.
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Step blade -Danba-
This term refers to a blade with an angled structure toward the tip of the blade. The main purpose is to prevent chipping by making the cutting edge obtuse while maintaining the overall thinness of the cutting edge. Depending on the width of the stepped blade, it is called a small blade (Koba), an thread blade (Itoba), etc.
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Sub-zero Treatment
A low-temperature treatment that maintains knives in a low-temperature state for a certain period after heat treatment, using liquid nitrogen or liquid oxygen. This process ensures durability in cold regions, stabilizes the hardness achieved through heat treatment, and prevents dimensional changes after heat treatment.
Sulfur
This element is harmful to steel and is hot brittle, i.e., it makes the steel brittle when it is in a red-hot state.
The content should be as low as possible.
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Sujibiki
A type of Western knife, it is a double-edged knife with a thin, long blade similar to a sashimi knife. The long blade is often used to cut large chunks of meat.
T
Tamahagane
A high-quality steel with very few impurities, used as a material for Japanese swords.
Tempering (Yaki-modoshi)
A process of reheating quenched steel to an appropriate temperature and cooling it over a certain period. Since quenched steel is brittle, tempering imparts toughness and wear resistance.
Tip -Kissaki-
The part of a kitchen knife that refers to the tip of the cutting edge. It is often used for delicate tasks.
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Titanium Coating
There are two types of common titanium knives: those that use a titanium alloy as the blade material, and those that coat the surface of a stainless steel knife with titanium to finish it. Both are primarily for home use. Titanium is more resistant to rust and corrosion than stainless steel, so it has the advantage of being rust resistant and lightweight.
However, when titanium alloy is used as a blade, it is difficult to get a good cutting edge due to its low hardness. In addition, the coating has the weakness of exposing the steel material inside when sharpening.
Toughness
Toughness affects the durability of a knife. Hardness and toughness are opposites. A kitchen knife is structurally vulnerable to shocks applied from the side, and toughness is necessary to prevent breakage and spills. A knife with a good balance between sharpness and durability is an easy-to-use knife. To achieve both hardness and toughness, ingredients such as molybdenum and vanadium are added to the steel material.
<Japanese Knife Materials 4 points>
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Traditional craftsman
Traditional craftsman is a title given by the Minister of Economy, Trade and Industry to craftspeople who have worked long and hard to pass on and improve their superior skills in traditional Japanese industry and craft production, and who have passed a rigorous examination.
Sakai-uchi cutlery, which has a history of 600 years, is supported by the skills passed down from generation to generation by traditional craftsmen.
At KIREAJI, you can purchase knives made by traditional craftsmen Tadayoshi Yamatsuka, Shougo Yamatsuka, Satoshi Nakagawa, and Keijiro Doi.
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Tread blade -Itoba-
This is one of the stepped blades provided mainly to prevent chipping. Compared to a small blade, a thread-thin blade is attached to the blade to make it sharper.
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Tungsten
It also improves wear resistance.
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U
Uchihamono
It is a traditional manufacturing method that has been passed down from the production of Japanese swords, among others. It involves heating soft iron and steel in a furnace and shaping them with a hammer to create the desired form. Unlike mass-produced blades, which often have molds, this method relies on the skill of the craftsmen to shape the blades according to sample models.
As a result, this method is not suitable for mass production like stamped blades, and the unit cost tends to be relatively high due to the lack of cost benefits from quantity. However, the absence of molds allows for the production of a wide variety of knives, which is a significant advantage.
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Usuba
This knife is used for cutting vegetables.
The edge of the blade is thin and has a straight edge.
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Urasuki -Back plow-
However, it's not always guaranteed that both the ura-ha and the ura-se will make even contact with the whetstone, as the blade can warp or twist. That's why it's important to check for wobble before you start sharpening. If there is any part of the ura-ha that doesn't touch the stone, it means that only half the sharpness can be achieved. Minor problems can be corrected by applying pressure to the back of the ura-ha, but if the knife still doesn't make contact with the stone no matter how much you sharpen it, it's best to consult a professional knife sharpener.
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V
Vanadium
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V Gold 10
This is one of the stainless steels developed by Takefu Special Steel Company, also known as "VO10". It is also known as "VO10". As a stainless steel for professional kitchen knives, it is referred to along with Ginji No. 3, and is especially popular among Western cooks because of its wide variety of Western-style kitchen knives. V-Gold 2, which has lower carbon content and higher corrosion resistance, and V-Gold 5, which has increased carbon and molybdenum content and added vanadium to balance hardness, wear resistance, and corrosion resistance, are preferred as blades for food processing machinery and kitchen knives for general household use; cobalt, etc. is added in addition to chromium to achieve high hardness and long-lasting sharpness. Most of the steel used for Damascus patterns is made of this V-Gold No. 10.
W
Wa-bocho(hocho)
The general term for Japanese-made knives that have been used alongside Japan's culinary culture is "Wa-bocho." In the context of practical use, it refers to single-edged knives such as "usuba," "deba," and "yanagiba," which are commonly used in Japanese cuisine. In recent years, due to their growing popularity overseas, some foreign individuals perceive "Wa-bocho" as synonymous with Japanese knives, including double-edged blades and knives with riveted handles.
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Western knife
This refers to the type of knives that developed in Japan, such as the traditional Japanese knives, compared to the knives that mainly originated from the West and their related knives, represented by the butcher knife that entered Japan during the Meiji era. They are double-edged and often have a design where the handle is fixed with rivets. While traditional Japanese knives have specialized functions depending on their use, Western knives are characterized by having versatile blades that can handle various ingredients. Examples of Western knives include santoku knives, butcher knives, and petty knives.
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Whetstone
A stone used to restore the sharpness of knives. There are small square grinding stones, large disc grinding stones, etc.
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White Steel -Shirokou, Shirogami-
Also known as "Shirogami". High-purity iron sand is used as the raw material, with small amounts of impurities such as phosphorus and sulfur mixed in with the iron and carbon. It has a sharp cutting edge and is the basic steel material for Japanese kitchen knives. Depending on the carbon content, there are White 1, White 2, and White 3 steels. [White 1 Steel] White 1 is made by adding more carbon to Shirogami 2. It produces the sharpest cutting edge of all steels, but its manufacturing process is difficult, and only a few skilled craftsmen can handle this steel. Therefore, it is very expensive and has high rarity value. [White 2 Steel] White 2 is made by further removing impurities from Yellow 2. It has good sharpness and is highly valued by chefs
< Blue Steel & White Steel >
Difference between Blue Steel and White Steel
Blue steel is an alloy carbon steel in which alloying elements are added to white steel to improve sharpness and durability. Therefore, blue steel has advantages over white steel, such as being "chip-proof" and "sharpen-proof. The price of knives made of blue steel is also higher because of the higher cost of raw materials.
Advantages |
Disadvantages |
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Blue |
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White |
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Difference between #1 and #2 in carbon steel type
The amount of carbon contained varies, with #1 and #2 being the most abundant in that order. The more carbon is contained, the harder the material is and the longer the sharpness lasts. However, it is also easier to chip.
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Y
Yakibashi (Clay Coating for Quenching)
A clay applied to the blade before quenching to prevent uneven heating or to create a temper line by differentiating the areas that will be hardened from those that will not. Some blacksmiths have secret formulas for this clay mixture.
Yakinamashi
Yakinamashi is performed to even out the unevenness of the tissue caused by the heat applied during shaping. Yakinamashi is completed by heating the knife to 750-800 degrees Celsius and allowing it to cool gently.
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Yanagiba
This is a Japanese knife that can be used to make sashimi without destroying the fibers of the fish meat. This knife is necessary for those who cook fish such as sashimi.
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Yanagiba (Kiritsuke)
Yanagiba (Kiritsuke), which is used for slicing sashimi, has the same purpose as a regular Yanagiba, but its tip is shaped like a beveled blade, making it easier to separate the ingredients.
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Yanagiba (Sakimaru)
Yanagiba (Sakimaru) features a mirror-finished surface with graceful ripples reminiscent of the elegance and dignity of a Japanese sword.
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Yasuki Steel
This is the brand name of steel manufactured at the Yasugi Works of Hitachi Metals, Ltd. in Shimane Prefecture. In Shimane Prefecture, steel production by tatara iron manufacturing has flourished since ancient times, and Yasugi City was a shipping port for the steel produced in that area. Today, the Yasugi Works of Hitachi Metals, Ltd. is located in Yasugi. YSS YASUKI HAGANE is a steel produced at the Yasugi Works based on traditional steelmaking technology and cutting-edge technology, and is used for kitchen knives and other products. The lineup includes the Shirogami series, the Aogami series, and the Ginshi series.
Z
ZDP189
Hitachi Metals' strongest powder steel boasts a hardness of 67 or higher, the highest of any known steel for cutting tools, and the ultimate combination of hardness, toughness, wear resistance, and corrosion resistance. However, due to its extreme hardness, it is difficult to sharpen with regular sharpening stones and is quite expensive.
*Production has been discontinued.
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Zenkou (All Steel)
The thickness is uniform and there is no line on the blade (cutting edge) part. Although it is called all-steel, most of the steel used is cheap and the price is the cheapest. This also depends on the material.
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