When it goes wrong · Sharpen
The knife is no sharper after long effort on a stone.
Can you save it?
Reviewed for this symptom
Recoverable with patience. Colour the bevel with a marker pen, take a few strokes and look: if the ink is gone from the shoulder but not the apex, lower the angle. Hold that angle constant on a coarse stone until a burr forms along the whole edge, then refine.
How to confirm the diagnosis
Observable cues, not inferred user state
- No burr can be felt on the opposite face after many strokes
- Scratches sit high on the bevel rather than at the edge
- The edge still skids on a tomato skin
Not this?
What actually happened
Only this symptom
The angle was not held, so metal was removed from the shoulder rather than the apex. Consistency matters more than pressure or time.
The full mechanism
Shared by every sharpen failure
A knife edge is two ground faces meeting at an apex a fraction of a micron wide. Two different things go wrong with it. In normal use the thin apex rolls to one side; the metal is all still there, just bent, and running the blade along a honing steel pushes it back into line. That is honing, not sharpening, and it is what most people mean when they say they sharpen weekly. Actual sharpening removes metal on an abrasive stone to re-form an apex that has been worn away or chipped, and it is needed far less often. Cutting force rises steeply as the apex widens, which is why a blunt knife is dangerous: it needs more pressure, and it slides off a surface instead of biting into it, with your hand behind all that force.
The full Sharpen lesson — how to tell, where to practise it, what it carries to.
Next time
Prevent this specific failure
Fix the angle before you count strokes — consistency matters more than pressure or time, and a guide or the marker trick keeps it honest.
What right looks like
Shared by every sharpen failure
- A sharp knife bites into the skin of a tomato under its own weight; a blunt one skids across it.
- Drawn lightly across a thumbnail, a sharp edge catches and a blunt one slides.
- A burr — a faint wire of metal you can feel on the opposite face — means you have ground far enough on that side and should turn the blade.
- The angle is held constant throughout the stroke; wobbling rounds the apex instead of forming it.