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How to sharpen a Japanese knife (and keep it that way)
Written for the steels on this site. Where a maker says something specific — Hinoura's manual, Tadafusa's stone — we say so.
What you need
Shapton Kuromaku #1000 (orange)
シャプトン 刃の黒幕 #1000
#1000 · ¥3,500–4,600
The stone most sharpeners overseas start with; hard, stays flat, cuts hard steels like Aogami Super and SKD.
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Tadafusa #800 sharpening set
タダフサ 砥石#800 研磨セット
#800 · ¥6,600 (official)
Sold by the Sanjo maker for its own knives — a good match for SLD/Aogami Tadafusa blades.
The angle
Double-bevel knives (santoku, gyuto, petty, nakiri, sujihiki)
- Soak or splash. King-type stones soak 10 minutes; Shapton Kuromaku only needs a splash. Put the stone on a wet towel so it cannot slide.
- Set the angle once. About 15° per side. Hold it by lifting the spine roughly two coins' height on a 50 mm-wide blade. Keep the angle; move the knife, not your wrist.
- Work in three sections. Heel, middle, tip. Push away with light pressure on the edge-leading stroke, ease off on the return. Ten strokes per section.
- Feel for the burr. Run a thumb across (never along) the edge on the opposite side. A tiny rough lip along the whole length means that side is done. Flip and repeat.
- Chase the burr down. Alternate sides with lighter and lighter strokes on the same stone until the burr is barely there.
- Finish. Move to #3000 (or #5000 for a polished edge on kasumi blades) and repeat with light pressure. Strop on newspaper or the palm-side of a leather belt to remove the last of the burr.
- Test on paper, not your thumb. A sharp edge slices newspaper cleanly in both directions.
Single-bevel knives (deba, yanagiba, usuba, takobiki, sake-kiri)
- Lay the bevel on the stone. There is no angle to choose: the wide bevel (切刃) sits flat. Raise the spine a hair for the very edge only if the maker ground a micro-bevel.
- Sharpen the front until a burr appears on the back along the whole edge.
- 裏押し (uraoshi): lay the back completely flat on a fine stone (#3000 and up) and take 3–5 light strokes. Never lift the spine on the back side — that is how the hollow (裏スキ) gets destroyed.
- Deba specifics: the heel is ground thicker for bones. Sharpen the front half of the edge thinner than the heel. Chips from bones are ground out on #400–800 first.
- Hinoura's own advice (from their manual): single-bevel knives chip and need more frequent sharpening than double-bevel; practise on inexpensive knives before touching a good one.
By steel
| Steel | Stone progression | What it feels like |
|---|---|---|
| Shirogami #2 (White #2) | 1000 → 3000–6000 | Hitachi/Proterial Yasuki carbon steel. Easiest to sharpen, takes the finest edge, rusts fast. |
| Aogami #2 (Blue #2) | 1000 → 3000–6000 | White #2 plus chromium and tungsten: better wear resistance, a touch harder to sharpen. |
| Aogami Super | 1000 → 3000 (a diamond plate helps) | Longest edge life of the Hitachi carbon steels. Kiryu Kogyo tempers it to HRC 64–65 inside stainless cladding. |
| SK carbon steel | 1000 → 3000 | JIS general carbon tool steel. Cheaper than Yasuki paper steels; Kenshin lists it alongside White steel. |
| SKD (semi-stainless tool steel) | 1000 → 3000 | Cold-work tool steel with ~12% chromium. Yoshikane's signature: stains slowly, sharpens like a carbon steel. |
| SLD | 1000 → 3000 | Hitachi's SKD11-type cold-work steel. Tadafusa's stainless-clad home line and Kenshin's hammered line use it. |
| VG10 | 1000 → 3000 | Takefu Special Steel's stainless with cobalt. The default steel of Tojiro's DP/PRO lines; also in damascus lines. |
| SG2 / R2 (powder stainless) | 1000 → 3000–5000 | Powder-metallurgy stainless. Long edge life, chips if abused. Kataoka's TAMAHAGANE and Kiryu's SPG2 line. |
| AUS10 | 1000 → 3000 | Aichi Steel stainless, often as a clad core in Tsubame factory knives (ROKUSHIRO). |
| CROMOVA 18 | 1000 → 3000 | Yoshikin's proprietary stainless used in every GLOBAL knife since 1983. |
| Molybdenum-vanadium stainless | 1000 → 3000 | Workhorse stainless in Brieto professional knives and household lines from Tsubame factories. |
Keeping the stone flat
Every 2–3 sessions rub the stone on a diamond plate (or #220 stone) under running water until pencil lines drawn across it disappear. A dished stone rounds double bevels and ruins single-bevel backs.
Care after sharpening
Carbon steel (Shirogami / Aogami / SK)
- Rinse and wipe dry immediately after each use — never leave it wet or in the sink.
- Do not put in the dishwasher. Do not cut acidic foods and walk away (lemon, tomato, onion will stain within minutes).
- A grey-blue patina is normal and protective; orange rust is not. Remove orange rust with a rust eraser or #1000 stone slurry.
- Before storing for more than a day, wipe with camellia oil (椿油) or any food-safe oil.
- Store dry, in a saya or on a rack — not loose in a drawer.
Semi-stainless (SKD / SLD)
- Stains slowly rather than rusting fast, but still wipe dry after use.
- No dishwasher. Oil is optional for long storage.
- Holds an edge longer than Shirogami; sharpen on #1000 → #3000 and expect a little more time on the stone.
Stainless (VG10 / AUS10 / molybdenum / CROMOVA / SG2)
- Wipe dry after use. Dishwasher still not recommended — the heat and detergent dull the edge and loosen handles.
- Powder steels (SG2) chip rather than roll: avoid bones, frozen food and twisting cuts.
- Sharpen on #1000; finish on #3000–5000 if you like a polished edge.
Stainless-clad carbon (割込 / 三枚 with carbon core)
- Only the exposed core at the edge can rust. Dry the edge line after use.
- Same rules as carbon for the edge; the cladding forgives everything else.
Kurouchi / black-forged finish (黒打)
- The black scale is a forge finish and protects the blade; do not scrub it off with abrasives.
- Below the black band the polished steel behaves like carbon steel — dry it.
What not to do
- No dishwasher, no pull-through sharpeners on hard steels (they tear chips out of Aogami Super, SG2 and SKD).
- No frozen food, bones (except a deba's heel) or twisting cuts with thin Japanese edges.
- No steel honing rod on very hard blades; use a fine ceramic rod or the #3000 stone instead.
- Don't polish off a kurouchi (黒打) or black-dyed (黒染) finish — it is part of the knife.
Sharpening services in Sanjo
Nakajo Kanamono runs a sharpening counter (切味販売処, 三条市東裏館2-21-6). Tojiro's Open Factory and Tadafusa's shop take re-sharpening for their own knives. Stock Busters advertises 包丁研ぎ承ります (sharpening accepted). Tadafusa sells a #800 sharpening set (¥6,600) for its own line.