How to sharpen a Damascus knife on a whetstone研ぎ

What you need

A combination 1000/6000 water stone: the 1000 side creates the edge, the 6000 side polishes it. A damp cloth underneath so it doesn't slide, and water to soak it (about 10 minutes, or until it stops bubbling).

The angle: 15 degrees

This is the secret of the Japanese cut. Lay the blade flat on the stone and lift the spine until two stacked one-euro coins fit under it: that is about 15°. Keep that angle constant through the whole stroke; it matters more than pressure or speed.

1000 side: create the edge

1. Place the knife diagonally on the stone, edge towards you.
2. With the fingers of your other hand on the blade, push from heel to tip with light pressure, as if you wanted to slice a very thin layer off the stone.
3. Repeat 10–15 times per side. You are done when you feel a burr (a thread of metal) along the whole edge when you carefully run a fingertip perpendicular to it.

6000 side: polish

Same strokes, even lighter pressure, 5–8 per side, alternating. The burr disappears and the edge becomes a mirror. To check, cut a sheet of paper held by one end: it should go in without pulling.

How often

With monthly honing, a whetstone sharpening every 3–6 months in a home kitchen. If you cut every day, every 2–3 months. A well-sharpened Kaen lasts a lifetime.