How to Sharpen a Knife Using a Whetstone

Updated September 2026 · 11 min read · Santoku Knives, Japanese-steel knife specialists

A whetstone is the oldest and still the best way to sharpen a kitchen knife. It is also the only method we would put near a hard Japanese blade: VG10 and AUS-10 sit around 60–61 HRC, which is hard enough to take a very fine edge and brittle enough that a pull-through sharpener can chip it. Done properly, ten minutes on a stone will leave a knife sharper than it was in the box.

This guide covers the whole job from a standing start: choosing a stone, preparing it, the six sharpening strokes, how the technique changes between knife shapes, how to tell when you are finished, and how to look after the stone afterwards.

Table of contents

What is a whetstone?

A whetstone is a flat block of abrasive that removes a thin layer of steel from the edge of a blade, re-forming the two bevels until they meet in a clean line. "Whet" is an old English verb meaning to sharpen; it has nothing to do with the stone being wet, which is why oil stones are whetstones too.

Modern kitchen stones are almost all synthetic, bonded from aluminium oxide or silicon carbide. Synthetics are consistent from batch to batch and cut predictably, which is exactly what you want when you are learning. Natural stones exist and some are superb, but they vary and they are expensive.

A stone is not the same thing as a honing steel. A stone removes metal and makes a blunt knife sharp. A steel removes no meaningful metal; it pushes a rolled edge back into line between sharpenings. You need both, and they are not interchangeable.

Water stone or oil stone?

This matters more than anything else on this page, because getting it wrong ruins the stone permanently.

• Water stones are softer and more porous. They are soaked in plain water and release a fine slurry as you work, which does much of the cutting. They are fast, they suit hard Japanese steel, and they are what almost every Japanese knife owner uses.
• Oil stones are harder and denser. They are used with a few drops of light honing oil, which floats the swarf clear. They cut more slowly and last a long time.

Never put oil on a water stone. Oil soaks into the pores, cannot be washed out, and the stone stops cutting for good. Our Whetstone Sharpening Stones are water stones, so they take water and nothing else. If you have inherited a stone and are not sure which you have, there is a simple test.

Which grit whetstone should you use?

Grit is a measure of how coarse the abrasive is. Lower numbers cut faster and leave a rougher edge; higher numbers refine what is already there. Each grit has one job:

You do not need four separate stones. Our Whetstone Sharpening Stones are two double-sided blocks covering 400/1000 and 3000/8000, which is the whole range in one purchase. If you buy only one thing, make it a 1000-grit face — that is where the actual sharpening happens.

How to sharpen a knife with a whetstone, step by step

1. Soak the stone. Submerge a water stone for about ten minutes, until the stream of bubbles stops. Water only, never oil.
2. Set it down on a damp cloth. A folded tea towel under the stone stops it sliding. Keep a little water to hand.
3. Find the angle. Lay the blade flat on the stone, then lift the spine to roughly 15°. Two £1 coins stacked under the spine of a 7-inch blade is close enough.
4. Push, edge-first, and reset. Slide the blade away from you across the full length of the stone with light, even pressure. Lift it clear, bring it back, and start again. Work one section of the edge at a time, from heel to tip.
5. Sharpen until you feel a burr. After 20 to 30 strokes, run a fingertip carefully across the back of the edge (never along it). A faint wire catching your finger along the whole length is the burr. Then turn the knife over and do the same on the other side.
6. Refine, then remove the burr. Move to the 3000 face and repeat with lighter pressure, then finish with a few very light alternating strokes on each side to wipe the burr away. Rinse and dry the knife.

That is one sharpening. For a knife you use daily, it takes five to ten minutes and needs doing every month or two. For a fuller explanation of why the push stroke works the way it does, see should you push or pull when sharpening a knife, and if the burr is the part you are stuck on, we have a whole guide to feeling for it.

What we use

Whetstone Sharpening Stones 400/1000 3000/8000

Two double-sided water stones covering repair, sharpening, refining and polishing. The stone this guide is written around.

£59.99 · 4.87 ★ (121 reviews)

Haruta 13 Inch Diamond Sharpening Steel

For between sharpenings, not instead of them. Straightens a rolled edge in a few seconds so the stone comes out less often.

£54.99 · 4.88 ★ (114 reviews)

What angle should you hold the knife at?

About 15° per side for a Japanese knife in VG10 or AUS-10, which is roughly 30° measured across the whole edge. Western knives are usually ground wider, at 18–20° per side, which is more durable and less keen.

Fifteen degrees is hard to picture, so use something physical. Stack two £1 coins under the spine of a 7-inch blade and the angle is about right; a matchbook folded in half does the same job. The important thing is not hitting exactly 15°, it is holding whatever angle you pick steady for the whole stroke. A wandering wrist rounds the bevel and is the single most common reason a knife will not come sharp.

We go into this properly, including how the angle differs on single-bevel knives, in our guide to the correct Japanese knife sharpening angle.

Does the knife shape change anything?

Less than most people expect. Every double-bevel knife we sell — santoku, gyuto, nakiri, kiritsuke, petty, boning — is sharpened at the same angle, on the same grits, until the same burr appears. The steel is the same and the procedure is the same. What changes is only how you move the blade across the stone.

• Flat-edged knives (santoku, nakiri). The edge is nearly straight for most of its length, so the blade stays flat on the stone and you simply slide it. Only in the last inch, where the spine curves down to meet the tip, do you lift the handle very slightly to keep the edge in contact. This is why a santoku is the easiest knife to learn on.
• Curved knives (gyuto, chef's knife, kiritsuke). These have a pronounced belly, so as you work towards the tip you raise the handle progressively, sweeping through the curve to keep the edge touching the stone all the way round.
• Serrated knives (bread knives). Not on a flat stone at all — each scallop needs a tapered rod. There is a separate method here.
• Single-bevel knives (yanagiba, deba, usuba). Ground on one face only and sharpened quite differently. We do not stock them, but it is worth knowing the distinction exists.

Work the edge in thirds. Whatever the shape, do not try to sharpen the whole blade in one pass. Divide it into heel, middle and tip. Do ten to fifteen strokes on the heel section, check for a burr there, then move along. It is far easier to keep the angle honest over three inches than over eight.

The grip. Pinch the blade just ahead of the handle with your dominant hand, thumb on the spine and forefinger on the flat. Rest two or three fingertips of the other hand on the blade near the edge — those fingertips supply the downward pressure, while the pinching hand does nothing but hold the angle. Separating the two jobs is most of the technique.

How do you know when the knife is sharp?

Three checks, in the order you should use them:

• The burr. The only test that tells you whether you have actually reached the edge. If there is no burr along the full length, keep going — nothing else matters yet.
• The paper test. Hold a sheet of printer paper by one corner and slice down through it. A sharp knife cuts a clean, quiet line. A blunt one tears, or skates off the top edge.
• The tomato test. Rest the blade on the skin of a tomato and draw it back with no downward pressure at all. If it bites straight in, you are done.

Sharpen both sides of the blade. Almost every knife we sell is double-bevelled, so both sides do equal work, and grinding only one side will skew the edge over time.

Common mistakes to avoid

• Oil on a water stone. The one genuinely irreversible mistake. Water only.
• Letting the angle wander. Changing angle mid-stroke rounds the bevel. Lock it in and keep it there; an angle guide helps while you build the muscle memory.
• Pressing too hard. Let the stone do the work. Heavy pressure digs in and dulls the very edge you are refining.
• Skipping the burr. Swapping sides before a burr forms means you never reached the edge.
• Letting the stone dry out. Keep the surface wet so the swarf does not clog the abrasive. The grey slurry that builds up is doing useful work, so do not rinse it away mid-session.
• Reaching for a pull-through sharpener. Most are fixed at a Western angle and remove far more steel than a stone does, which on a hard, thin Japanese edge means chipping and a shorter knife life. The same goes for most electric sharpeners.

Caring for your whetstone

A stone hollows in the middle with use, and a dished stone rounds the edge you are trying to straighten. Flatten it every few sessions with a lapping stone, or by rubbing it on wet-and-dry paper laid on a sheet of glass, until the face is even again. There is a full walkthrough here.

Afterwards, rinse the slurry off, wipe the stone down and let it air-dry rather than sealing it away wet. Stored well, a good synthetic stone lasts for years. Replace one when it has cracked through, or when it has worn so thin it can no longer be flattened.

How often should you sharpen?

For a knife in regular home use, a full sharpening every one to two months is plenty, with a few passes on a honing steel in between. A professional kitchen knife might want it weekly. The honest answer is to sharpen when the knife stops passing the tomato test, not on a schedule — we go into the timing here.

A new knife is the exception. One bought from a specialist arrives sharpened and ready to work, and putting it straight onto a stone removes steel for nothing. Use it first.

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