Japan — Sakai (Osaka) and Tsubame-Sanjo (Niigata) as primary knife production centres; Hitachi Metals (Yasugi, Shimane) as reference steel producer; modern VG10 from Takefu Special Steel (Fukui)
The metallurgy of Japanese kitchen knives — specifically the distinctions between shirogane (white steel / hagane no shiroko), aogane (blue steel / hagane no aoko), and stainless alloy steels (most notably VG10 and VG5) — constitutes a genuine technical discourse that seriously affects cutting performance, edge retention, sharpening characteristics, and maintenance requirements. Shiroko (white steel, also called shiro hagane) is the purest form of high-carbon steel in Japanese knife making — essentially iron with only carbon (1.1–1.3% for Shiroko No.1) as the alloying element, with minimal impurities. This purity produces an extremely hard, very sharp edge that cuts with minimal resistance but requires frequent maintenance and will rust and stain if not dried immediately. Aogane (blue steel) adds small amounts of tungsten and chromium to the white steel base, producing greater edge retention and wear resistance with slightly more forgiveness — the added alloy elements reduce the brittleness of the pure white steel. Aogane No.1 and No.2 are the primary grades (No.1 harder and more edge-retentive; No.2 slightly softer and more forgiving to sharpen). VG10 (and its successor VG10+) is a stainless steel alloy from Takefu Special Steel that adds cobalt and vanadium to achieve high hardness (approximately HRC 60–62) with genuine corrosion resistance — used by Misonoya, Global, and Spyderco kitchen knives. The experienced Japanese chef typically uses shirogane (white steel) for primary cutting work where ultimate sharpness matters, and may use stainless or aogane for tasks where rust vulnerability would be problematic.
No direct flavour contribution — steel quality determines the quality of cuts which affects the texture and eating quality of raw fish and vegetables in Japanese cuisine
{"Higher purity (fewer alloy elements) in white steel produces sharper initial edge but lower edge retention and maximum corrosion sensitivity","Blue steel's added tungsten and chromium extend edge retention at slight cost to absolute sharpness ceiling — the professional compromise","VG10 stainless enables maintenance-free anti-rust performance at the cost of being harder to sharpen than carbon steel on a whetstone","Hardness (HRC scale) determines edge retention and brittleness simultaneously — higher HRC can take a finer edge but is more prone to chipping on hard materials","The cladding (jigane) around the core steel affects rust behaviour and aesthetics — stainless-clad carbon steel (warikomi construction) offers carbon edge with easy-clean body"}
{"Shiro hagane No.1 (white steel #1) produced by Hitachi Metals (Yasugi, Shimane) is the reference material for premium yanagiba and deba knife making","Aogane No.2 is the most practical choice for professional daily use — slightly easier to resharpen than No.1, with adequate edge retention for kitchen pace","The patina on well-used shirogane is a protective oxide layer — maintaining a stable rust-brown patina through regular use and drying is preferable to polishing it off","Whetstone grit progression for Japanese knives: coarse (220–400) for edge repair, medium (1000–2000) for edge setting, fine (3000–6000) for polishing, finishing (8000–12000) for final edge","Honyaki construction (full forge of single steel, no cladding) is the highest-level Japanese knife construction — requires master-level heat treatment skill and commands prices above ¥100,000"}
{"Putting any high-carbon (shirogane, aogane) Japanese knife in a dishwasher — immediate rust and potential warping from thermal shock","Using a pull-through sharpener on Japanese single-bevel knives — these tools are designed for symmetric European knives and damage single-bevel geometry","Applying too much force when sharpening thin-bladed Japanese knives on a whetstone — the thin geometry is fragile; light, consistent pressure is essential","Storing Japanese knives in a knife block long-term — humidity accumulation inside block channels causes rust on carbon steel"}
Tsuji, S. (1980). Japanese Cooking: A Simple Art. Kodansha. (Chapter on knives and cutting tools.)