Stropping: A Strip of Leather That Outperforms Another Stone

Glue a strip of vegetable-tanned leather, rough side up, to a flat hardwood board about 300 x 60 mm. Press it flat under weights until the glue cures. Rough side up because the nap holds the compound. Vegetable-tanned because chrome-tanned leather carries salts that will spot a carbon steel blade. The board matters as much as the leather — a strop that flexes is a strop that rounds your edge, which is the one thing stropping must not do. Leave the other face bare. A clean, uncharged leather surface is useful for the final few passes once the compound has done its work.

Rub the compound bar across the leather until the surface is evenly coloured, then work it in with a finger or a smooth offcut. A charged strop looks uniformly tinted, not caked. Too much compound builds a soft layer that the edge sinks into, and that layer rounds the apex — the exact failure stropping is supposed to avoid. Recharge when the surface goes shiny and stops cutting, which on a hand-tool strop is every few months, not every session. Compound grades run from coarse to fine; a single fine compound around one micrometre is enough for nearly all workshop tools. Keep one strop per grade if you use more than one, and never mix them on one surface.

Lay the bevel flat on the leather and draw the blade BACKWARDS, spine first, away from the cutting edge. Then turn it over and do the same on the other side. Light pressure, ten to twenty passes a side. Pushing edge-first into leather does two things and both are bad: the edge digs in and cuts the strop, and the leather rolls up ahead of it and folds the apex over. A blade that came off the finish stone sharp will come off a wrongly-stropped strop blunt. Keep the bevel flat. Lifting the spine as you draw back is the other common fault; it rounds the edge into a convex profile a little more with every pass, and after a few months the tool needs a full regrind to recover.

Make stropping the thing you do between cuts rather than a stage of sharpening. Twenty passes takes fifteen seconds and restores an edge that has only just started to dull. The economics are plain: a strop removes a fraction of a micrometre and a coarse stone removes tens of micrometres. Every trip to the stone shortens the tool. A chisel kept sharp by stropping will outlive the maker; one allowed to go blunt and then reground each time will be worn out in a career. It stops working when the edge has real damage — a nick, a rolled section, a flat you can see under the lamp. At that point go back to the stone and follow the progression. Stropping maintains an edge; it does not create one.