4.3 Caring for and sharpening a knife

A good knife can last for many years, even a lifetime, if it is looked after. A whetstone is better than a manual or electric sharpener, because a stone gives the cook more control. Machines often grind away too much metal, so the blade wears down far faster than it should.

Soft steel and hard steel

• Western-style knives (the usual European kind) are mostly made of softer steel. They are easier to sharpen and can be kept going with a honing rod, but they go dull a little sooner.
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• Japanese-style knives use harder steel. They take a finer edge and keep it longer, but they are harder to sharpen well.
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A hard, high-carbon knife needs more care. Never put it in the dishwasher, and never run it through an electric sharpener, which tears off extra metal.

Stones and grits

A water stone must be soaked in water before use; the water lubricates it.

• 300 is for a knife in very bad shape that needs a whole new edge ground on it. It suits softer Western knives, not hard steel.
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• Around 1000 is where most cooks can do most of their sharpening, then finish on about 2000.
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• 6000 or 8000 gives a polished, mirror-like finish, used for a special knife such as a Japanese sashimi knife.
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Work from a coarser stone toward finer ones. You do not need every stone, though: even 800 alone gives a very sharp edge. Good technique matters more than the stone, and it comes with practice.

Setting up the stone

• Put a towel in a tray and set the stone on top.
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• Flatten the top of the stone with a stone fixer before you start. Dips or hollows in the surface make it hard to sharpen the knife evenly.
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• Leave the slurry where it is. This is the muddy paste of tiny ground particles that forms on the wet stone, and it is what actually sharpens the knife. Do not rinse it away.
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• Keep the stone wet the whole time you work. Gray, silty liquid gathering on the blade is normal.
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Bevels and angles

• A double-bevel knife is ground to the same angle on both sides, so the edge sits in the middle.
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• A single-bevel knife is ground mostly on one side, often in a split of about 90% to 10%.
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On a double-bevel knife, the angle of each side is usually about 20 degrees on a Western knife. On a Japanese-style knife it is usually about 15 degrees, sometimes 17.

Small guides that set the angle can be bought, but a little arithmetic is simpler. Take the width of the blade (measure it, or judge it by eye) and divide it by four. Raise the spine (the back of the blade) off the stone by that much, and you are near 15 degrees. Divide the width by three instead and raise it by that, and you are near 20 degrees. With experience, you can judge the angle by eye.

The sharpening stroke

• Hold the handle in one hand; that hand gives the pressure. Rest the fingers of the other hand on the blade to keep the pressure even.
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• Place the heel of the blade (the end nearest the handle) at the far end of the stone.
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• Draw the knife slowly back toward you. Use the whole length of the stone and pass the whole length of the blade over it. Hold the same angle all the way.
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• Press only lightly. Press a little more as you pull back, and very lightly as you push forward. A heavy push can let the edge dig into the stone and chip both the stone and the knife.
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• Give one side 16 to 20 strokes. Turn the knife over and give the other side the same.
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• Keep turning it, with fewer strokes each time: 8, then 4, then 2, and at last one stroke on each side in turn.
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Cutting down the strokes this way grinds both sides evenly. It stops too much metal coming off one side, and stops the very edge from rolling over on itself.

Practice and the burr

Do not expect it to work the first time. A first try can leave a knife no sharper, or even duller. With practice the work gets faster, the angle starts to feel natural, and a cook learns to feel the burr on the edge. If you are nervous, learn on a cheap knife first. Fine scratches on the side of a blade are normal on a knife that is used a lot.

A well-sharpened knife can cut a tomato into slices so thin they are nearly see-through.

Honing rods and strops

Do not use a honing rod on a hard-steel knife. The rod can crack or chip such a blade and do more harm than good. If a cook insists on using one, they should use no pressure at all.

For hard steel, use a strop instead: a strip of leather fixed to a block, like the leather strap a barber uses.

• Rub the green polishing paste that comes with it onto the leather.
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• Hold the knife at the same 15-degree angle as on the stone.
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• Only pull, with the edge trailing. Never push the edge forward into the leather, or it will cut it.
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Stropping gives the edge its final alignment. When a knife starts to cut a little less well, a strop will bring the edge back, up to the point where the knife is truly dull and needs the stone.

How often to sharpen, and daily care

There is no fixed timetable. One approach is to rotate several knives, use each until it is annoyingly dull, then sharpen a batch together, a couple of times a year at most. A hard-steel knife can go a very long time between sharpenings.

A knife keeps its edge only if it is not abused:

• Always cut on a cutting board.
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• Do not cut through bones.
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• Do not cut through frozen food.
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• Never cut on glass.
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Storing knives

Never keep knives loose in a drawer, where they knock together and lose their edge. Use a knife block that fits inside the drawer. At the very least, fit each knife with an edge guard, a plastic or leather sleeve that covers the blade.