The core difference
Shirogami (White Paper Steel) is pure high-carbon steel — minimal alloying, maximum simplicity. It takes a sharper edge than Aogami because there are no chromium or tungsten carbides to interrupt the apex. But that purity is also its weakness: without alloying elements, the edge wears more quickly. Aogami (Blue Paper Steel) adds chromium and tungsten — elements that form incredibly hard carbides that resist abrasion. The edge dulls more slowly, but those same carbides prevent Aogami from reaching the absolute apex keenness of Shirogami.
Sharpening feel and frequency
Shirogami sharpens almost effortlessly — even cheap 1000-grit stones cut it quickly. The steel's simplicity means abrasives have nothing to fight against. For craftsmen who sharpen frequently and enjoy maintaining their tools, Shirogami is rewarding and immediate. Aogami resists sharpening more — not dramatically, but noticeably. The tungsten carbides that give it edge retention make it slightly harder work to bring to a refined edge. If you sharpen only occasionally and prefer a tool that stays sharp through sustained work, Aogami rewards that working style better.
Rust behavior
Both rust. Quickly. Neither has chromium content significant enough to resist oxidation — Aogami's 0.2–0.5% chromium is for carbide formation, not stainless behavior. A Shirogami chisel left in a damp workshop overnight will show surface rust. Aogami is marginally more resistant. Both require the same discipline: wipe the blade after use, apply a thin coat of camellia oil, store in a dry environment. Anyone unwilling to follow this protocol should consider laminated stainless tools.
The verdict by use case
Choose Shirogami if: you sharpen frequently and enjoy the process; you do fine finishing work where maximum keenness matters; you work primarily in softwoods. Choose Aogami if: you prefer to sharpen less often; you work primarily in hardwoods or dense exotics; you do heavy stock removal where edge retention matters more than ultimate keenness. Both steels should be in a complete collection — they serve different purposes.
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