Carbon steel · ProterialShirogami #1 白紙1号
Also called: White #1 · Shiro #1 · White paper steel #1
Shirogami #1 is a non-stainless carbon steel from Proterial (formerly Hitachi Metals): 1.25–1.35% carbon, no chromium, and a maker hardening hardness of ≥60 HRC.
Composition
| C | Si | Mn | P | S |
|---|---|---|---|---|
| 1.25–1.35 | 0.10–0.20 | 0.20–0.30 | ≤0.025 | ≤0.004 |
Mass %. As published by the steelmaker (typical or representative values). Hardness: ≥60 (hardening hardness).
What the data says
Shirogami #1 is the highest-carbon grade of Proterial’s “White” family: 1.25–1.35% carbon with only small, tightly limited amounts of silicon and manganese, and phosphorus and sulfur held to ≤0.025% and ≤0.004%. Proterial describes the White steels as carbon steel with minimum impurities and rates #1 as the “highest hardness” of the three.
There is no chromium in the composition, so the steel is not rust-resistant. Like other plain carbon steels it develops a patina with use and will rust if left wet.
Compared with Shirogami #2, the only difference in the published composition is about 0.2% more carbon. Compared with Aogami #1, which shares the same carbon range, Shirogami #1 has no tungsten or chromium added.
Shirogami #1 compared with similar steels
| Steel | Type | C % | Cr % | Maker HRC | CATRA mm |
|---|---|---|---|---|---|
| Shirogami #1 | Carbon | 1.25–1.35 | — | ≥60 | — |
| Shirogami #2 | Carbon | 1.05–1.15 | — | ≥60 | — |
| Aogami #1 | Carbon | 1.25–1.35 | 0.30–0.50 | ≥60 | — |
| Aogami Super | Carbon | 1.40–1.50 | 0.30–0.50 | ≥60 | 338 @ 65.1 |
Detailed comparison: Blue vs White steel
See all 15 steels in the Japanese knife steel chart, or compare up to three at once in the steel explorer.
Care
Shirogami #1 is not stainless. Wipe the blade dry after use; a grey or blue patina is normal, but orange spots are rust and should be removed early.
Buying a Shirogami #1 knife from a shop in Japan? Japanese kitchen knives currently pay about 31% US import duty — use the import duty calculator to compare with a US retailer.
Frequently asked questions
- Is Shirogami #1 stainless?
- No. Shirogami #1 has no chromium in the maker’s composition, while a stainless steel needs roughly 10.5% or more, so it can rust if left wet.
- How hard is Shirogami #1?
- Proterial publishes a hardening hardness of ≥60 HRC. The hardness of a finished knife depends on the knifemaker’s heat treatment.
- Who makes Shirogami #1?
- Shirogami #1 is made by Proterial (formerly Hitachi Metals).
- Shirogami #1 vs Shirogami #2: what is the difference?
- Shirogami #1: C 1.25–1.35%, no Cr, maker hardness ≥60 HRC. Shirogami #2: C 1.05–1.15%, no Cr, maker hardness ≥60 HRC.
Sources
Checked 2026-10-21. Found a better source or an error? Tell us.