• Japanese Knife Materials

  • By introducing the materials used in knives, we aim to help customers understand the quality and performance of knives, enabling them to find the perfect knife that meets their needs and preferences.

Iron, in its raw state, is riddled with impurities, making it prone to rust and brittleness—less than ideal for kitchen knives. By removing these impurities and adding carbon, iron is transformed into carbon steel, enhancing its hardness and durability for culinary use.

Carbon Steel:

Characterized by a carbon content of 0.04-2.14%, this material strikes a balance between hardness and edge retention, making it a popular choice for many kitchen knives.

Stainless Steel:

The game changes when over 10.5% chromium is introduced to carbon steel, evolving it into stainless steel, celebrated for its exceptional resistance to rust. This meticulous alloying process crafts knives that are not just high-performing but also durable, able to withstand the rigors of kitchen life.

Element

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Carbon(C)

Carbon (C) is an essential element for steel, and it is a key element in creating various compounds and elements. It is a representative element for increasing hardness and strength.

Chromium(Cr)

Chromium (Cr) improves hardenability. Stainless steel contains 10.5% or more of Cr.

Manganese (Mn)

Manganese (Mn) is an element that makes quenching easier and increases toughness.

Molybdenum

Molybdenum is used to make V1 to V10. (It is originally contained in V1 as well.) Adding a small amount makes it more tenacious. It also increases strength and hardness. Molybdenum steel is often referred to as molybdenum steel, but molybdenum steel is a general term for steel materials that contain molybdenum. It is not the name of a specific steel material, such as white steel, but a steel material that contains molybdenum is widely referred to as "molybdenum steel.

Phosphorus (P)

Phosphorus (P) is a harmful element in steel, which causes cold brittleness, making steel brittle in cold conditions. Therefore, it is necessary to limit its content as much as possible.

Silicon(Si)

Silicon (Si) is an element that increases hardness and strength.

Sulfur(S)

Sulfur (S) is a harmful element for steel as it causes hot-shortness, meaning it makes the steel brittle when in a red-hot state. The content of sulfur should be as low as possible.

Tungsten(W) 

Tungsten (W) is an element that improves heat treatment characteristics and increases hardenability. It also improves wear resistance.

1. Carbon Steel

  • Carbon steel, used in kitchen knives, combines iron with carbon to enhance hardness, sharpness, and edge retention. While it outperforms materials like stainless steel in cutting ability and is easier to sharpen, carbon steel requires careful maintenance to avoid rust and can be more prone to chipping due to its hardness. It's ideal for experienced cooks who prioritize sharpness and are diligent in their tool care.

  • When choosing a knife, the type of steel used plays a major role in its performance and ease of use. Especially for professional chefs or those who are particular about their knives, selecting the right steel is a crucial factor. The sharpness retention, ease of sharpening, and durability—each type of steel has its unique characteristics, and the best choice depends on the user's skills and intended use.

  • SK Steel:

    • A common carbon steel used for tools like knives.
    • Often found in affordable household knives.
    • The carbon content is typically around 0.55% to 1.5%.

  • Yellow Steel (Kigami Steel):

    • Based on SK steel, with around 50% high-purity iron sand added.
    • It offers better quality than SK steel but still contains more impurities compred to white or blue steel.
    • It is relatively affordable and easy to sharpen.

  • White Steel (Shirogami Steel):

    • A highly pure steel made by further removing impurities from yellow steel.
    • It is known for being easy to sharpen and having an exceptionally sharp edge.
    • However, it is difficult to heat treat, requiring the skill of a master craftsman.

  • Blue Steel (Aogami Steel):

    • An alloy steel made by adding chromium and tungsten to white steel.
    • It is highly wear-resistant and retains its sharpness for a long time.
    • While it is tougher and more resistant to chipping than white steel, it can be more difficult to sharpen.

  • Relationship:

    As you progress from SK steel → Yellow steel → White steel → Blue steel, the purity, quality, and performance improve.
    At the same time, the price increases, and the difficulty in handling also rises. Each type of steel is chosen based on its purpose and the user's skill level.

White Steel vs Blue Steel

  • White Steel (Carbon Steel): Choose for Ease of Sharpening

    Features: White steel is favored for its ease of sharpening and excellent cutting performance. It can be sharpened to a sharp edge quickly, although the sharpness may decrease with frequent use. The quick resharpening process allows for easy maintenance of optimal sharpness.

  • Blue Steel (Alloy Steel ): Choose for Lasting Sharpness

    Features: By adding chromium (Cr) and tungsten (W) to carbon steel, blue steel's sharpness durability significantly improves. It can maintain good sharpness with infrequent sharpening, even with high volume cutting. However, while blue steel maintains sharpness longer due to its components, it is harder to sharpen. Additionally, the enlargement of the metal's structure can slightly decrease sharpness.

  • Differences between Steel #1, Steel #2, and Steel #3

  • While knives have a silver appearance, when sharpened, the slurry produced turns black. This is because the slurry contains carbon, a key component that provides the knife with hardness.

  • The hardness of steel is classified as #1, #2, and #3, with lower numbers indicating greater hardness. For example, Steel #1 offers the highest level of hardness and provides the sharpest edge. Steel #2 and Steel #3 follow in order, with progressively lower hardness and sharpness, though they still maintain sufficient sharpness for most purposes.

  • It is often said that the more carbon steel contains, the better the sharpness. This is because the carbides formed in the steel provide more grip when cutting, which contributes to a sharper edge. Additionally, harder steel has better edge retention, allowing the blade to stay sharp for longer periods.

  • One of the advantages of harder steel is that it requires less force to cut. For example, when knives with different hardness levels are sharpened at the same angle and used with the same force, the harder steel will generally cut more effectively. However, as steel becomes harder, it also becomes more prone to chipping and is more difficult to sharpen.

  • Steel #1: Focused on Sharpness

    #1 is recommended for knives that require exceptional sharpness, such as those used for slicing delicate dishes like fugu sashimi or thin slices of sea bream, due to its excellent cutting ability.

  • Steel #2: Focused on Balance

    #2 offers a good balance between sharpness and ease of sharpening, making it suitable for cutting a variety of ingredients, from vegetables to meats.

  • Steel #3: Focused on Ease of Sharpening

    #3 is easy to sharpen, making it ideal for knives that may chip, such as those used for filleting fish, since it can be quickly resharpened.
White_Steel_vs_Bule_Steel

Blue Steel #1:

The steel with the best edge retention.

Blue Steel #2:

A balanced steel in terms of sharpness and durability.

White Steel #2:

A standard steel in the Hagane series.

 Features of Blue Steel #1

  • Blue_Steel_2_Mukimono_190mm

    Extremely High Hardness and Sharpness

    Blue Steel #1 is a material known for its high carbon content, which contributes to its exceptional hardness. When properly sharpened, it can achieve an impressively sharp edge.

  • Blue_Steel_2_Yanagiba_Kiritsuke_330mm-Mirror_Polished_one_side

    Excellent Wear Resistance

    Due to its high hardness, knives made from Blue Steel #1 maintain their sharpness for extended periods, holding their edge better compared to regular knives.

  • Sharpening_a_knife

    Challenging to Handle

    Blue Steel #1 is extremely hard, which makes it difficult to sharpen and may not be suitable for beginners. Due to its hardness, the sharpening stone can slip, requiring a skilled technique to sharpen effectively.
Blue Steel #1

Features of Blue Steel #2

  • Blue_Steel_2_Mukimono_190mm

    Stable Sharpness

    Blue Steel #2, known for its high carbon content, is extremely hard. This quality allows it to maintain a sharp edge for an extended period once sharpened.

  • Blue_Steel_2_Yanagiba_Kiritsuke_330mm-Mirror_Polished_one_side

    Wear Resistance

    Due to its high hardness, knives crafted from Blue Steel #2 retain their sharpness longer than regular knives, offering superior wear resistance.

  • Sharpening_a_knife

    Hard to Sharpen

    Blue Steel #2 is hard, making it challenging to sharpen and requiring skilled maintenance or extra effort. Compared to Blue Steel #1, it has better abrasion resistance on sharpening stones, making sharpening easier.
Blue Steel #2

Features of White Steel #2

  • White-Steel-2-Kamausuba-210mm-Mirror-Polished-both-sides

    Sufficiently Sharp Edge

    White Steel #2 is a material with a high carbon content, making it extremely hard. When sharpened, it exhibits a sharp edge.

  • Sharpening_a_knife

    Not Highly Difficult to Sharpen

    White Steel #2 is not as hard as blue steel, so it is not highly difficult to sharpen. It can be considered relatively easy to handle even for beginners.

  • White-Steel-2-Yanagiba-300mm-Mirror-Polished-one-side

    Good Cost Performance

    White Steel #2 is not as expensive as the top-grade White Steel #1, making it a good choice in terms of cost performance.
White Steel #2

Comprehensive Guide to White Steel #2 and Blue Steel #2

Explore the essential differences between White Steel #2 and Blue Steel #2 in our guide, focusing on their cutting performance, durability, and ease of sharpening. This article provides practical insights for chefs and cooking enthusiasts to make an informed choice between these two popular steel types for kitchen knives.

White Steel #2 vs Blue Steel #2

Comprehensive Guide to Blue Steel #1 and Blue Steel #2

Explore the key differences between Blue Steel #1 and #2 knives, focusing on sharpness, durability, and user needs, to help you choose the right one for your cooking tasks.

Blue Steel #1 vs Blue Steel #2

  • 2. Stainless Steel
Stainless Steel

Stainless steel, with added chromium, offers rust resistance and has seen improvements in sharpness due to technology, approaching carbon steel's performance. Its durability and low maintenance, along with a variety of grades, make it an increasingly popular choice.

  • ZDP189

    Hitachi Metals' strongest powder steel, ZDP-189, boasts a hardness of 67 or higher, the highest of any known steel for cutting tools. It offers the ultimate combination of hardness, toughness, wear resistance, and corrosion resistance. However, due to its extreme hardness, ZDP-189 is difficult to sharpen with regular sharpening stones and is quite expensive.

  • Ginsan

    Ginsan is a type of stainless steel known for its excellent balance between corrosion resistance and cutting performance. Manufactured by Hitachi Metals, this steel is widely recognized under the name "Ginsan." It features a high chromium content of 13-16%, which significantly enhances its resistance to corrosion. Additionally, the carbon content ranges from 0.8 to 1.3%, providing a good balance between hardness and toughness, ensuring stability during use.

    Due to its superior sharpness and resistance to rust, Ginsan is extensively used in various types of blades, including kitchen knives. Trusted in both professional kitchens and homes, Ginsan steel makes daily culinary tasks more efficient and enjoyable.
Yanagiba_Kiristuke

Understanding Stainless Steel: The Rust-Resistant Alloy

Stainless steel, enriched with elements like chromium, nickel, and vanadium, is celebrated for its corrosion resistance, a breakthrough in metallurgy achieved in 1913 by Harry Brearley. This advancement has led to widespread adoption in kitchen knives, particularly appreciated in settings like sushi restaurants for their ease of maintenance and hygiene. Recent innovations in high-carbon stainless steel have further enhanced these knives' sharpness, rivaling traditional carbon steel.

Stainless Steel
White-Steel-2-Kamausuba-210mm-Mirror-Polished-both-sides

Japanese Knife Materials 4 Points

Knife material quality is defined by hardness, wear resistance, toughness, and corrosion resistance. These factors intricately determine sharpness, durability, and maintenance needs. Understanding their interplay unveils the essence of blade quality and its price range.

Japanese Knife Materials 4 Points

The Origin of Craftsmanship

  • The Miraculous Fusion of Iron and Carbon: Creating the Balance of Hardness and Flexibility

  • Creating steel is like manipulating iron and carbon as if they were living beings. As blacksmiths, our goal is not just to create something hard, but a blade that combines flexibility and strength. By carefully adjusting the carbon composition, we achieve a cutting edge that glides effortlessly through ingredients while also ensuring long-lasting durability.

  • The delicate balance of strength and flexibility in a blade is created through a momentary temperature control and the skilled ability to gauge the movement of carbon. No matter the material, the blade cuts with power, beauty, and smoothness.
Sakai Traditional Craftsmen Collection

KIREAJI's Three Promises to You

  • japanese_knife_made_in_Sakai

    1. High-quality Japanese Knive

    We offer knives crafted by craftsmen from Sakai City.

  • Honbazuke

    2. Genuine Sharpness

    To ensure you experience sharpness, we provide a free Honbazuke by our skilled craftsmen.

  • 3. Lifetime Knife Use

    Every knife comes with a free Saya(Sheath) for durability. We also provide paid after-sales services with Sakai City Japanese knife workshop.