Knife Making In Sanjō (With Aiba Steel) | Kenji Eats Japan

In this episode of his Japanese travel series, J. Kenji López-Alt takes professional cooks inside Aiba Steel, a renowned metalworking manufacturer in the Tsubame-Sanjō region of Niigata Prefecture. For any serious chef, the kitchen knife is the ultimate extension of the hand. Understanding how these tools are forged, ground, and finished is essential for selecting and maintaining the right blade for heavy-duty kitchen service.

The Heritage of Sanjō Metalworking

Tsubame-Sanjō has been the epicentre of Japanese blacksmithing and metalwork for centuries. At Aiba Steel, the focus is on merging heritage techniques with modern industrial precision. Unlike small-scale boutique workshops that produce only a handful of blades a week, this facility demonstrates how high-quality steel is processed at scale without sacrificing the structural integrity of the metal. For chefs, seeing the raw steel undergo heating, stamping, and precise grinding demystifies the metallurgy behind their daily tools. The video highlights how controlled industrial processes ensure consistency in hardness and bevel angle, reducing the microscopic structural flaws often found in purely amateur-forged blades.

Blade Geometry and Steel Tempering

The performance of a kitchen knife depends heavily on heat treatment and blade geometry. Aiba Steel’s manufacturing showcases how raw metal is transformed into high-performance clad steel, where a hard core steel is sandwiched between layers of softer, more durable stainless steel. This combination provides the edge retention of high-carbon steel with the corrosion resistance and flexibility of stainless steel.

For the working line chef, understanding this cladding is crucial. It dictates how you thin the blade during sharpening and how the edge behaves under high-impact prep work. The tour also sheds light on the grinding process, showing how the taper from spine to heel is carefully calibrated to ensure smooth food release and minimal wedging during intensive vegetable prep.

What This Means on the Pass

Investing in a knife from a dedicated maker like Aiba Steel or a collaborator like Vonhelmick Knife Co. isn't just about aesthetics; it is about ergonomics and balance. When a manufacturer pays meticulous attention to weight distribution and the radius of the spine and heel, it translates directly to reduced wrist fatigue during twelve-hour shifts. Watching the precision of Sanjō's knife makers reinforces why professional cutlery requires respect, correct whetstone maintenance, and an understanding of the specific steel alloy in your kit.