How to Sharpen a Knife on a Whetstone

To sharpen a knife, hold the blade at a steady 15 to 20 degree angle on a wet 1000-grit whetstone and grind until a small burr forms along the whole edge, flip and repeat on the other side, then refine on a finer stone and remove the burr. A honing rod keeps that edge aligned between sharpenings, but it does not sharpen.

What "sharp" actually is

A knife edge is where two bevels meet. Under magnification, a dull edge is rounded, flattened, or rolled over to one side, so it presses on food instead of cutting it. Sharpening grinds fresh metal off both bevels until they meet in a clean, narrow apex.

A sharp edge is also a safer edge. It needs less force, so it is less likely to skid off an onion or tomato skin into your hand. It cuts cells cleanly rather than crushing them, which is why sharp knives give crisper vegetables and greener herbs.

Honing vs sharpening

If honing brings back the bite, the edge was rolled. If it does not, the edge is worn and needs a stone.

Choosing a stone

• 220 to 400 grit: repair. Removes chips and reshapes very dull blades.
• 1000 grit: the workhorse. Sets a new edge on a normally dull knife.
• 3000 to 6000 grit: refinement. Polishes away scratches for a smoother, longer-lasting edge.

A combination 1000/6000 stone is a great first purchase. Some stones need soaking for 10 to 15 minutes until bubbles stop; "splash-and-go" stones just need a wet surface. Follow the maker's instructions.

Steps

1. Soak or wet the whetstone as directed. Water carries away metal particles and keeps the stone cutting.
2. Set the stone on a damp towel, coarse side up. The towel or a rubber holder keeps it from sliding.
3. Find the angle: 15 degrees for Japanese knives, 20 degrees for Western. Picture 90 degrees with the blade upright, halve it to 45, halve it again to about 22. Lower slightly from there. As a check, at 20 degrees the spine sits about a third of the blade's height off the stone (roughly 1.5 cm for a chef's knife 4.5 cm tall); at 15 degrees, about a quarter. Consistency matters more than the exact number.
4. Grind one side along the whole edge until you feel a burr. Place two or three fingertips on the flat of the blade near the edge and push the knife across the stone, edge leading, in sections from heel to tip. Use moderate pressure, about the weight you would use to press a kitchen scale to 1 to 2 kg. Keep going until you can feel a slight rough lip, the burr, along the entire opposite side.
5. Flip the knife and grind the other side until the burr moves back. Same angle, same number of strokes. The burr will flip to the first side.
6. Repeat on the finer grit with lighter pressure. Ten to twenty strokes per side refine the scratch pattern. Reduce pressure as you go.
7. Remove the burr with alternating light strokes or a strop. Finish with single, feather-light alternating strokes on each side, then a few edge-trailing passes on leather, cardboard or newspaper. A burr left on will break off in use and leave the edge dull.
8. Test the edge, then rinse and dry the knife and stone. Slice a sheet of paper or a tomato. Let the stone air-dry fully before storing, away from direct heat.

How to hone

Hold the rod vertically with its tip on a towel. Place the heel of the knife at the top of the rod at your sharpening angle and draw the blade down and toward you so the whole edge, heel to tip, touches the rod. Alternate sides, 5 to 8 light strokes each. Pressure should be gentle; you are straightening, not grinding.

Chef Fizz says: A sharp knife is a safe knife. A dull knife is a sneaky one, because it slips right when you are not looking.

Common mistakes and fixes

• Rocking the angle: the edge rounds off and never gets sharp. Lock your wrist and move from your shoulder and elbow. Colour the bevel with a marker; if ink is left at the very edge after a few strokes, your angle is too low.
• No burr forms: you have not ground long enough, or the angle is too high or low. Keep going on the coarse stone.
• Skipping the tip: the curve needs a slight lift of the handle as you move toward the tip so the stone keeps contact.
• Dishing the stone: stones wear unevenly. Flatten them every few sessions with a flattening plate or coarse sandpaper on glass.
• Using pull-through sharpeners on fine Japanese knives: they can be too aggressive and fixed at the wrong angle.

Keeping it sharp longer

Cut on wood or plastic boards, never glass, stone or ceramic plates. Hand-wash and dry knives immediately; dishwashers knock edges against other items. Store in a block, magnetic strip or blade guard, not loose in a drawer.