Sharpening Kitchen Knives with a Whetstone

Pick your grit and angle before you start

The default for most home cooks is a combination stone, 1000 grit on one side and 6000 on the other. The 1000 side does the real sharpening, and the 6000 side polishes. Here's when to pick something else:

• For a chipped knife, or one that hasn't been sharpened in years, a 400 grit stone saves you 20+ minutes of grinding.
• For softer Western steel, a 1000/3000 combo is plenty. A very high polish won't last long on soft steel anyway.
• Serrated bread knives, ceramic knives and single-bevel Japanese knives (sharpened on one side only) need different tools or methods. Leave them out of this plan.

The angle depends on the knife. Most German and American knives take about 20 degrees per side, and most Japanese double-bevel knives take about 15 degrees. On a typical chef's knife with a blade about 2 in (50 mm) tall at the heel, that means lifting the spine roughly 11/16 in (17 mm) off the stone for 20 degrees, or 1/2 in (13 mm) for 15. Holding the same angle on every stroke matters far more than hitting the exact number.

Use the marker to check your angle

The most common first-timer mistake is sharpening at the wrong angle without realizing it. Color the edge bevel with a permanent marker, do 3 to 4 strokes, then look at where the ink came off:

• Ink gone only at the very edge: you're too steep, so lower the spine.
• Ink gone only near the top of the bevel: you're too flat, so raise the spine.
• Ink gone evenly: lock in that angle.

This 2-minute check saves you 15 minutes of grinding the wrong spot. Re-ink and check again any time you're unsure, especially at the tip.

Let the burr decide when to move on

Grinding one side long enough raises a tiny lip of metal on the opposite side, called the burr. To check for it, slide a fingertip gently off the edge on the side facing away from the stone. Move from the spine toward the edge, perpendicular to the blade and never along it. You should feel a slight catch.

• Work in 3 sections: heel, middle, then tip. Stay on each section until the burr runs along that whole stretch, then repeat on the second side.
• Mind the curve: as you reach the tip, lift the handle slightly so the curved belly meets the stone at the same angle. Skipping this is why tips stay dull.
• Spend your time on the coarse side. Raising the burr is the actual sharpening and takes the longest. The fine side is quick: about 10 strokes per section on each side, then alternate with 5, 3 and finally 1 stroke per side.
• Pressure: press about as hard as pushing 2 to 3 lb (1 to 1.5 kg) on a kitchen scale, with 2 to 3 fingertips flat on the blade near the edge. Ease off as you finish. Keep your fingertips on the flat of the blade and move slowly. Speed adds nothing.

Leave the gray slurry that builds up on the stone, because it helps the grinding. Only add water when the surface starts to look dry.

Several knives, testing and upkeep

Budget about 25 to 30 minutes for a dull chef's knife on your first try, and 10 to 15 minutes for a paring or utility knife. With several knives, start with the one you use most while you're fresh. Then do every knife on the coarse side before flipping the stone once for all the fine work. A sharp knife slices a sheet of printer paper held in the air cleanly and quietly, with no tearing or snagging. It should also bite into a tomato skin under its own weight. If it snags at one spot, go back to the coarse side for that section only. Between sharpenings, give the knife 3 to 4 light passes per side on a honing rod before each use to keep the edge straight. You only need the stone again when honing stops bringing the edge back. Every few sessions, flatten the stone: draw a pencil grid on its surface and rub it on 220 grit wet/dry sandpaper laid on glass or a flat tile until the grid is gone.