A Japanese kitchen knife is made to last decades. Well-cared-for ones are passed down through generations — a good Sakai knife on a professional cook's bench is very often forty or fifty years old, still working, still sharp.
What that requires from you, the person using it, is smaller than most care guides make out. Three habits — the right cutting board, careful washing, and knowing when the edge needs work — cover the vast majority of what a home cook needs to know. This is a practical guide to those three, drawn from what the Sakai bladesmiths themselves teach.
For an introduction to the knives, our Sakai kitchen knives explainer covers the bladesmithing tradition, the shapes, and the steel decisions. This piece is about what happens next — after the knife is in your hand.
The cutting board matters more than you think
Ask most people what dulls a kitchen knife, and they may say "cutting food". It turns out there is actually a different major factor.
One of the Sakai makers, Sakai Ichimonji Mitsuhide, who publishes well-referenced care guides and columns on kitchen knives, puts it plainly: the biggest cause of a knife losing its edge is not the food. It is the cutting board. Every downward stroke through an onion or a fillet of fish is also a stroke into the board underneath. Food is soft. The board is not. And it's the board, not the food, that wears the edge over time.
The best surface for a Japanese knife is wood. Wood has a gentle elasticity that cushions the blade as it passes through the food, letting the edge come to rest against something forgiving rather than something hard. It's also easier on the wrist. Softer than wood and it wouldn't hold vegetables steady; harder, and you're just replacing the food-and-board equation with something more punishing.
Plastic and rubber boards are easier to sanitise and dishwash — a real advantage for hygiene, especially when working with raw meat — but they're harder on the edge. If you have to keep one for meat, keep a wooden one for everything else and rotate.
Ceramic, glass, and stone boards will ruin a Japanese knife in weeks. Avoid them.
Wash, dry, and never the dishwasher
Everything else in the daily-care list is downstream of one rule: don't put a Japanese knife in the dishwasher.
The heat softens the steel's temper and can loosen a wooden handle. The detergent is aggressive on the edge. And the knife knocks against other cutlery during the cycle — which is where most chips originate. Even a single dishwasher run can leave a formerly sharp knife dull enough to notice.
Hand-wash instead, with warm water and a mild dish soap. Dry the blade immediately with a clean cloth. This matters particularly for carbon-steel knives (Aogami, Shirogami, and other traditional Japanese blade steels), which will start to rust within minutes if left wet. Stainless steel — the 440C and VG5 pieces we carry, for instance — is more forgiving, but the drying habit is worth keeping for both.
Don't leave a knife in a drying rack, or resting wet on a chopping board, or in the sink under a pile of other washing-up. It only takes a few days of that to see a difference.
How often to sharpen, and how to tell
Home cooks worry about this more than they need to. There is no fixed schedule.
The knife will tell you when it needs work. A useful test is slicing a ripe tomato. If the knife has to be pressed down rather than allowed to sink in under its own weight, the edge has gone.
For a home cook who cooks most days, a light re-sharpening every four to six weeks is typical. For once-a-week cooking, every three or four months is fine. What matters is that you notice the change and don't ignore it — a dull knife is more dangerous than a sharp one, because it slips.
Sharpening itself is a subject with several books written about it, together with plenty of YouTube videos. This article isn't going to pretend to teach the whole skill in a paragraph. If you've never sharpened a knife before, our honest advice: don't try to learn on your best knife in the middle of dinner. Buy an inexpensive middle-grit whetstone (around #1000), set aside an unrushed morning, and practise on an old knife you don't care much about first. Or, see the next section.
What to do if you chip the edge
Small chips — the size of a poppy seed or smaller — can usually be honed out with a middle-grit whetstone in fifteen or twenty minutes of patient work.
Larger chips need re-profiling with a coarser stone, and re-profiling is where amateur sharpening tends to go wrong. If the chip is more than a millimetre or two across, our advice is to send it out. Most specialist Japanese-knife retailers offer sharpening services or can point you to someone reliable; it's better to pay for a proper repair than to grind the profile out of shape trying to fix it yourself.
In Bristol, where we are based, we can recommend Sharpsmith Bristol — a workshop tucked behind Cargo 2 in Bristol Harbourside, typically open Tuesday through Saturday. He is highly recommended locally, though popular enough that there can be a small backlog — worth a look at his Facebook or Instagram for current hours before you make the trip. For readers elsewhere in the UK, any specialist Japanese-knife shop in a major city will either sharpen in-house or refer you on. When you enquire, worth asking about their experience with single-bevel (wa-bōchō) versus double-bevel (yō-bōchō) knives — the two require different techniques.
For very worn or badly damaged knives, the Sakai makers themselves still offer factory sharpening. Turnaround takes weeks (the knife is shipped to Japan and back), but for a knife you're serious about, it's the closest thing to a full reset.
Storage — four options, and one to avoid
Where a knife lives when it's not in your hand matters more than most people realise.
Magnetic strip. Mounted on a wall or splashback, the strip holds the knife by the flat of the blade. Easy to reach, easy to see, easy to put back safely. A good default for a home kitchen with adults only.
Wooden block. The classic. Keep it clean and dry — the slot at the back is a place for wet steel to rust if a knife goes back before it's fully dry. Fine as long as the knife goes in dry.
Saya (鞘). A wooden sheath, traditional in Japanese kitchens. Slips over the blade and protects the edge. The safer option if the knife lives in a drawer alongside other utensils, or if there are children in the house.
Knife roll. A cloth or leather roll with pockets for each knife. Handy for cooks who travel with their knives or want to keep a set together in a drawer.
One to avoid: loose in a cutlery drawer. The edge knocks against every other piece of metal, chips easily, and the exposed blade is a hand-injury waiting to happen. If a drawer is the only option, use a saya or roll.
The knife you look after
There is a phrase in Japanese for the practice we've just described: hōchō o sodateru (包丁を育てる) — literally, "to raise a knife". The idea is that a good knife isn't a static object you own; it's something you keep in relationship with over time. The knife you buy from us this year, if you look after it, will likely still be in your kitchen — or someone else's — in fifty. It's just what these knives do.
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For the tradition behind the knives themselves, our Sakai kitchen knives explainer is the companion piece to this one.
