Technical Explanation of Aike in Japanese Traditional Knives

October 22, 2024

  • What is 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.

  • Causes of Aike

    The primary causes of Aike include:

    • Low-temperature forging work
      To create high-quality knives, intentional low-temperature forging is sometimes employed. This temperature adjustment is a technical choice to maintain the carbon content of the steel and enhance its sharpness.
    • Impurities during the joining process
      Aike can also occur if debris or impurities enter the joint between soft iron and hagane. This type of Aike is known as "Aike that can be removed by sharpening" and has a higher likelihood of being corrected with proper maintenance.

  • Types and Characteristics of Aike

    • Aike that can be removed by sharpening
      This type of Aike is caused by debris or impurities and is often correctable through sharpening. Such knives may also be relatively inexpensive to obtain.
    • Aike that cannot be removed by sharpening
      This type results from structural joining defects and may lead to rust. Typically, these knives are not available on the market.

  • Discovering Aike and Its Impacts

    Aike typically appears as black lines or small holes on the blade's surface and can be identified through visual inspection by experts. If a knife with Aike is used unknowingly, especially one with "non-removable Aike," it may be prone to rust and impact the knife's durability. However, removable Aike can often be corrected through proper maintenance.

  • KIREAJI's Quality Control and Aike

    Traditional Japanese knives are handcrafted by artisans, so it's common for them to initially show signs of "Aike." In particular, many stores sell knives without sharpening them, which can lead to customers unknowingly purchasing knives with Aike. However, KIREAJI implements strict quality control during the final sharpening process, thoroughly checking for the presence of Aike. This ensures that customers can purchase knives with confidence.

  • Conclusion

    Aike is a phenomenon that can occur during the production of traditional Japanese knives and does not necessarily indicate a defect. In fact, there are types of Aike that can be corrected through sharpening. When purchasing a knife, it's important to understand the types and impacts of Aike and consider buying from stores that conduct proper quality control.

Manufacturing Process of Japanese Knife

Japanese kitchen knives are made by heating and forging metal, then bonding the blade to the softer iron cladding. In the sharpening process, the blade is first roughly ground, then refined with finer stones, and finally polished with a finishing stone. In the handle construction process, the tang is inserted into the handle, and the brand name is engraved before the knife is packaged. This describes the manufacturing process of a Japanese kitchen knife.

Manufacturing Process of Japanese Knife

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.

  • after_service

    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.