How to Use a Whetstone

Almost nobody fails at whetstone sharpening because of the stroke. They fail because the stone slid, dried out, dished, or was never soaked.

1. Find out what binder your stone has. Clay wants soaking; ceramic and magnesia do not. The roundup lists this per stone.
2. Soak or splash accordingly. A clay stone is ready when the bubbles stop, typically 10 to 15 minutes.
3. Secure it. Damp folded towel under the stone, on a stable surface at a comfortable height. Too low and you round your angle reaching down; too high and you cannot use your body weight.
4. Have water to hand. A small bowl or a spray bottle. You will need it every thirty seconds.
5. Color the bevel with a marker. Thirty seconds that replaces an hour of guessing.

Set the bevel flat on the stone at your angle. Lock your wrist. Move the knife with your upper body, not your hand — shoulders and elbows drive the stroke, which is what keeps the angle constant over the whole length.

Work in thirds. Heel third, middle third, tip third, so that every part of the edge gets equal attention. As you reach the curve toward the tip, lift the handle slightly to keep the contact point on the stone — the bevel angle stays the same, only the handle height changes.

Slurry is the gray paste of abrasive and steel that builds on the stone as you work. Loose abrasive in the slurry cuts faster and leaves a slightly less refined finish than the fixed abrasive in the stone.

• On a coarse or medium stone, leave it. It speeds things up and it is the feedback that tells you the stone is cutting.
• On a finishing stone, rinse it periodically. You want the fine fixed abrasive doing the work, not coarser loose particles.
• If it goes dry and gummy, add water immediately. A loaded stone stops cutting and starts burnishing.

Every stone wears fastest in the middle, because that is where you sharpen. Within a few sessions a soft stone develops a visible dish, and a dished stone makes a consistent angle physically impossible — the blade follows the curve and rounds the apex.

1. Draw a pencil grid across the stone face.
2. Run a flattening plate, a coarse diamond plate or a sheet of coarse wet-and-dry on glass across it with water.
3. Stop when all the pencil is gone. Remaining pencil marks the low spots.

Soft clay stones like the King need this often. Hard stones — Shapton Glass, Naniwa Professional — need it far less. It is one of the strongest arguments for a harder stone once you sharpen regularly.

• Rinse the swarf off under the tap. Do not use soap.
• Air dry completely before storing. Never store a soaking stone submerged.
• Keep it somewhere it will not freeze. Water in a saturated clay stone expands and cracks it.
• If the surface glazes over — shiny and slick rather than matte — it is loaded with swarf. A few passes with a flattening plate opens it back up.

The actual sharpening sequence is on how to sharpen a Japanese knife. The angle work is on the angle guide. If something is not working, start with the diagnostic.