What grits do I need for sharpening, and can I skip one?

The grit numbers on sharpening stones look like an intimidating range, and the underlying idea is simple: each grit's job is to remove the scratches left by the one before, and to do it fast enough to be worth doing. Skipping too far leaves scratches that the finer stone can only polish around, and a polished scratch is still a notch in the edge.

Step by step

1. Understand what each grit is actually for.A coarse stone removes metal fast and leaves deep scratches — its job is shape, not sharpness. A medium stone refines those scratches and is where the burr is raised, which means it is where the edge is actually created. A fine stone polishes the two meeting surfaces so the line between them is as fine as possible.
2. Note that sharpening stone grit numbers are not sandpaper grit numbers.Different scales are used for water stones, oil stones and diamond plates, and a 1000 grit water stone is not equivalent to 1000 grit paper. Compare within a system, and treat manufacturers' coarse/medium/fine descriptions as the more reliable guide.
3. Start at the coarsest grit only if you need to change the shape.Reach for the coarse stone for a chip, a rounded bevel, an edge out of square, or a first setup on a new tool. Never as part of a routine touch-up — it removes far more steel than the job needs and shortens the tool's life.
4. Do the real work on the medium stone.Work the bevel until a burr forms along the entire width of the edge. The burr is not a side effect; it is the proof that the bevel has met the back everywhere. Until it appears, the edge is not yet sharp anywhere and there is no point moving on.
5. Move up only when the burr is continuous.Check by drawing a thumbnail lightly across the back of the blade — the burr catches. If it catches along the full width, move up. If it catches for two thirds of the width, keep going on the same stone.
6. Polish on the fine stone and remove the burr.A few light strokes on the bevel, then the back flat on the stone, then the bevel again, alternating and reducing pressure until the burr breaks off rather than folding over. Finish on a strop if you have one.
7. Keep the routine short in normal use.A tool being used and touched up regularly only needs the fine stone and a strop, which takes under a minute. That is what makes sharpening a habit rather than an event.
8. Know when to go back down a grit.If the fine stone no longer raises a burr in a reasonable time, the secondary bevel has grown too wide to hone efficiently. Go back to the medium or coarse stone, re-establish the primary bevel, and start the cycle again.
9. Do not skip more than one step.Going from coarse straight to fine means the fine stone is asked to remove deep scratches, which takes far longer than the medium stone would have and wears the fine stone unnecessarily. Two or three stones in sequence is faster than two with a big gap.

Tips

• Three stones is genuinely enough. Beyond about 8000 grit the gains are real but very small for woodworking tools, and mostly matter for paring and for knives.
• A double-sided combination stone gives you two grits in one and is the cheapest sensible starting point.
• A coarse diamond plate is a good first purchase even if the rest of your stones are water stones, because it does the heavy shaping and it flattens the other stones.
• Keep the tool moving over the whole stone surface rather than wearing a hollow in the middle.

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