In the world of premium Japanese knives, two steels stand at the top of the carbon hierarchy: Hitachi White (Shirogami) and Hitachi Blue (Aogami). Both are legendary — but what really separates them at the metallurgical level?
Both White and Blue steels are made by Hitachi Metals using very pure iron ore and traditional smelting methods. They begin as simple carbon steels, offering excellent hardness, edge retention, and ease of sharpening.
| Feature | White Steel (Shirogami) | Blue Steel (Aogami) |
|---|---|---|
| Alloying Elements | None | Chromium, Tungsten, sometimes Vanadium |
| Sharpening Feel | Exceptional, very responsive | Slightly harder, less feedback |
| Edge Retention | High | Even higher |
| Toughness | Medium | Improved via alloying |
| Rust Resistance | Low | Slightly better, still carbon |
White steel is prized for its refined grain structure and incredible responsiveness on whetstones. It’s what traditional Japanese blacksmiths used for centuries, and it remains the go-to for: - Sushi chefs seeking flawless cuts - Traditional blade makers - Knives meant for regular sharpening
White #1 has the highest carbon (1.25–1.35%), sharper but more brittle.
White #2 is balanced and most commonly used.
White #3 has lower carbon and is easier to forge.
Blue steel starts with the same pure iron but is enhanced with chromium and tungsten. This results in: - Longer edge retention - Better wear resistance - A bit more durability
Aogami Super adds vanadium and higher carbon for extreme sharpness and hardness (up to 65–66 HRC).
Blue steels are popular among professional chefs who: - Need longevity without frequent sharpening - Work in high-volume environments - Want carbon feel with added strength
Think of White steel as raw precision, and Blue steel as optimized performance. One is purist, the other pragmatic. Both can produce exquisite knives — your choice depends on how often you sharpen, how you cook, and what kind of steel personality you prefer.
日本の高級包丁の中で、白紙鋼（しろがみ）と青紙鋼（あおがみ）は、最も評価が高い炭素鋼として知られています。どちらも日立金属製ですが、その違いは単なる色や名前以上のものです。
白紙鋼も青紙鋼も、高純度の鉄鉱石と伝統的な製法によって作られます。炭素含有量が高く、高硬度・優れた刃持ち・研ぎやすさを兼ね備えています。
| 特性 | 白紙鋼 | 青紙鋼 |
|---|---|---|
| 合金元素 | 無し | クロム、タングステン、バナジウム等 |
| 研ぎ味 | 非常に鋭敏で心地よい | やや硬めで、若干の抵抗感 |
| 刃持ち | 高い | さらに高い |
| 粘り強さ | 中程度 | 合金により向上 |
| 錆びにくさ | 非常に低い | わずかに改善（それでも錆びる） |
白紙鋼は粒子が細かく、研ぎ感が極めて優れているため、長年にわたり日本の職人に愛されてきました。
白紙1号：炭素量1.25〜1.35%、鋭いが脆い
白紙2号：バランス型、最も多く使われる
白紙3号：炭素量が少なめ、鍛造しやすい
青紙鋼は白紙鋼にクロムやタングステンを加え、耐摩耗性と刃持ちを向上させた鋼材です。
青紙スーパーはさらにバナジウムと高炭素を加え、硬度HRC65–66の極端な切れ味を実現。
白紙鋼は職人の美学、青紙鋼は現代の現場主義。どちらも素晴らしいが、用途や料理スタイル、研ぎ頻度によって最適な選択が変わります。あなたの「理想の鋼」はどちらですか？