Stainless
Stainless Steel
"Stainless" means stain-resistant, not stain-proof. In kitchen use, the steel can still discolour or pit if exposed to acidic environments — citrus, vinegar, or salt water — for extended periods. Wash and wipe dry after every use, and avoid leaving the blade soaking in water. With basic care, a stainless knife is very low-maintenance and a great everyday choice. PM / Powder Steel Powder Metallurgy (PM)
PM stands for powder metallurgy. Fine steel powder is consolidated under heat and pressure. This can produce a fine, even carbide structure, but performance still depends on the steel and its heat treatment. The PM label alone does not guarantee a harder, tougher or more chip-resistant knife. Hitachi Special Steel, Japan 🇯🇵
"Stainless" means stain-resistant, not stain-proof. In kitchen use, the steel can still discolour or pit if exposed to acidic environments — citrus, vinegar, or salt water — for extended periods. Wash and wipe dry after every use, and avoid leaving the blade soaking in water. With basic care, a stainless knife is very low-maintenance and a great everyday choice. PM / Powder Steel Powder Metallurgy (PM)
PM stands for powder metallurgy. Fine steel powder is consolidated under heat and pressure. This can produce a fine, even carbide structure, but performance still depends on the steel and its heat treatment. The PM label alone does not guarantee a harder, tougher or more chip-resistant knife. Hitachi Special Steel, Japan 🇯🇵
ZDP-247 ZDP-247（粉末ステンレス鋼・開発鋼種）
Hardness
Rockwell C Hardness(HRC) measures how resistant a steel is to permanent deformation. For kitchen knives:
55–58 HRC — Soft. Easy to sharpen and forgiving of rough use, but dulls faster. Typical of most German knives.
59–61 HRC — Balanced. Good edge retention with manageable sharpening. Common in mid-range Japanese knives.
62–64 HRC — Hard. Excellent edge retention, holds a very fine edge. Requires more care and a fine stone to sharpen.
65+ HRC — Very hard. Exceptional edge longevity but more brittle — more prone to chipping if used roughly.
Higher is not always better — it depends on how you use and maintain your knife.
55–58 HRC — Soft. Easy to sharpen and forgiving of rough use, but dulls faster. Typical of most German knives.
59–61 HRC — Balanced. Good edge retention with manageable sharpening. Common in mid-range Japanese knives.
62–64 HRC — Hard. Excellent edge retention, holds a very fine edge. Requires more care and a fine stone to sharpen.
65+ HRC — Very hard. Exceptional edge longevity but more brittle — more prone to chipping if used roughly.
Higher is not always better — it depends on how you use and maintain your knife.
63–64
HRC
555759616365+
ZDP-247 is a development grade from the Hitachi Metals (now Proterial) ZDP family, first made about thirty years ago: the maker has disclosed only that it is a powder stainless steel, to be heat-treated like SRS-13. A few smiths have forged it since the early 2000s, and roughly a ton of it remains. Sukenari's master smith Hanaki hardens it to 63-64 HRC and finds it easier to sharpen than ZDP-189, which our own testing confirms.
ZDP-247 Buying Guide
Should you buy ZDP-247?
Where it shines
- A powder stainless steel by the maker's own classification, in the ZDP family, hardened to 63-64 HRC by Sukenari
- Noticeably easier to sharpen than ZDP-189: Hanaki-san's word, and our own bench test agrees
- Made to be forged: a traditionally forge-welded Sukenari blade rather than a stock-removal blank
- Genuinely rare: a development grade whose specification the maker has not released, worked by very few smiths, with about a ton of the steel left in existence by Hanaki-san's account
Where it doesn't
- A development grade: the maker has disclosed only that it is a powder stainless steel, so its corrosion resistance is not documented. Its sibling ZDP-189 wears a stainless label and still rusts if left wet, so keep this one dry too until owners report back
- Still a very hard powder steel: good stones make a difference, even if it gives up a burr more readily than ZDP-189
- Its sibling ZDP-189 is known to chip on hard contact; assume the same until owners report back. Hanaki-san also notes that powder steels like SG2 and ZDP hold an edge and then drop off suddenly rather than fading, so the first sign of dullness means it is time for the stones
Knives in ZDP-247
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