How to sharpen a Japanese knife, step by step

A common question is simple: do Japanese knives need sharpening at all, given their reputation for staying sharp? They do, and the difference lies in how often and by what method. Shun, which makes Japanese-style knives, keeps the jobs apart. Honing helps keep the edge you already have by straightening it when it starts to roll, while sharpening restores true sharpness by taking away a small amount of metal.¹

The timing depends on how you cook. Shun says that for many home cooks, sharpening about once a year is often enough, while professional cooks and anyone using their knives heavily will probably need it more often.² Masamoto Sohonten, a Japanese knife maker, adds that a knife maintained properly can be used for a very long time, and that poor storage and neglected maintenance bring dulling, rust and a shorter life.⁵

That framing helps when you meet a complaint about chipped blades online. Shun answers it by pointing to technique, hard cutting surfaces and rust at the thin edge, and says micro chips can be sharpened out.⁶ A blunt or chipped knife is not necessarily a lost knife. It may be waiting for the right tool, and the rest of this guide sorts out which tool that is, from a honing steel to a Kyoto class.

Yoshikin, the maker of Global knives, calls a whetstone at home the best way to sharpen any type of knife, because it lets you keep the edge at the level you prefer and can repair edge damage.³ The maker names the stone as its preferred tool, so if you plan to own a good Japanese knife for years, a stone repays the money and the patience you put into learning it, and it will serve every blade in your drawer.

Masamoto Sohonten names three kinds of whetstone, rough, medium and finishing.¹⁸ For daily dulling it sharpens on the medium stone and then the finishing stone, and for nicks or a very blunt blade it starts with the rough stone to restore the shape first.⁸ Soak the stone in water for 5 to 10 minutes until bubbles stop, and spread a wet cloth beneath it so it cannot slip while you work.⁷

Stones wear into a dish, and a dished stone gives a poor edge. Masamoto Sohonten says to flatten a worn stone with a correcting tool, or at home by rubbing it on the back of another stone or on flat concrete.¹⁹ None of this needs expensive kit on the first day. A single medium stone, a cloth, a bowl of water and some patience are enough to begin, and you can add a rough or finishing stone later, once you know which part of the process you want to improve.

Once the edge is set, the work is not over. Masamoto Sohonten washes the newly sharpened knife, wipes it thoroughly dry, applies an oil coating, wraps it and stores it where there is little moisture.¹⁰ The oil step suits carbon steel, which Shun says needs additional care to prevent rust and corrosion, and a stainless blade may need less attention, but drying remains the habit that protects every edge.²²

Shun reminds owners that stainless steel knives can still develop rust, and that the cause is moisture left on the blade.²³ After sharpening, the edge is at its most exposed, so wash the slurry off, dry the blade at once, and put it away rather than leaving it on a damp board. A later page on this site covers storage and everyday care in more detail, including what to do about a blade that has started to spot.

Treat your stone as part of the set. Rinse away the slurry, flatten the face when it dishes, and let it dry before storing it somewhere with air. Keeping the stone flat is what lets you keep the angle steady, and a steady angle matters more than any particular grit number. If an edge comes out uneven, the usual remedy is to slow down, use less pressure and check the edge more often, rather than to buy a new stone.