How do I sharpen a carving gouge?

The two things that make this different from sharpening a chisel are that the edge is curved, so the bevel has to be presented to the stone at a continuously changing angle, and that the inside face is concave, so it cannot be flattened on a flat stone. Everything else — grit progression, the burr, stropping — works exactly as it does for any edged tool.

Safety

What you'll need

• Sharpening stones or abrasive on a flat surface
• Slipstones shaped to match your gouge sweeps
• A leather strop and honing compound
• A shaped or rolled strop for the inside of the flute

Step by step

1. Check what needs doing before you start.A tool that will not cut may only need stropping. Look at the edge under a light — a dull edge reflects a fine bright line, a sharp one reflects nothing. Only go to a stone if there is damage or the bevel has become rounded.
2. Match the stone angle to the existing bevel.Carving tools are usually ground at a shallower angle than a chisel because they are pushed by hand into softish wood. Feel where the bevel sits flat on the stone and keep it there.
3. Roll the gouge as you move it.The motion is a simultaneous forward stroke and a rotation from one corner of the edge to the other, so every part of the curved bevel gets the same treatment. Practise the movement on a dry stone first.
4. Work until a burr appears along the whole edge.Feel for it on the inside of the flute with a fingertip drawn away from the edge, never along it. A continuous burr all the way across means the two faces have met everywhere.
5. Remove the burr with a slipstone inside the flute.A slipstone whose curve matches or is slightly tighter than the flute, held flat against the inside surface. Keep it flat — tipping it creates an inner bevel, which changes how the tool behaves and is difficult to undo.
6. Alternate outside and inside as the burr flips.The burr moves from one side to the other as you work. A few strokes each side, decreasing in pressure, until it detaches.
7. Strop the outside on flat leather.Charged leather, edge trailing, rolling the tool as you did on the stone. This is what produces the final polish, and it is the step that most affects how the tool feels in the wood.
8. Strop the inside on a shaped strop.A piece of leather glued to a shaped wooden stick matching the sweep, or a rolled strip of leather, charged with compound. A gouge stropped only on the outside develops a wire edge that folds over.
9. Test on end grain.A sharp gouge slices end grain cleanly and leaves a shiny cut surface. A dull one crushes and tears. This is a more honest test than any amount of thumbnail work.
10. Sharpen a V-tool as three separate operations.Each wing is sharpened like a flat chisel, then the point where they meet is treated as a tiny gouge and rounded very slightly. The point is the part that always goes wrong and it needs the most attention.

Tips

• Strop constantly while carving — a dozen strokes every fifteen minutes — and you will very rarely need a stone at all.
• Make your own slipstones by gluing wet-and-dry paper to dowels and shaped sticks matching your gouges. It works and it costs almost nothing.
• Never take a carving gouge to a bench grinder unless you know what you are doing. It is very easy to burn the thin edge and lose the temper, after which the tool will never hold an edge again.

Common mistakes

• Creating an inner bevel by tipping the slipstone — It changes the tool's geometry so it no longer takes a controlled shaving with the bevel down, and correcting it means grinding the whole inner face back — a long job.
• Sharpening without rolling the tool — Only the middle of the edge touches the stone, so the corners stay blunt and the edge becomes progressively more pointed with each sharpening.
• Stropping only the outside — The burr folds back and forth and the tool feels sharp for a minute and then does not. Both faces need stropping.

Questions people ask