How do I strop a blade, and what do I strop on?

Stropping is the last stage of sharpening and the one that keeps an edge alive between sharpenings. It removes the burr left by the stones and polishes the two surfaces of the edge to a finer finish than a fine stone alone achieves. It also realigns an edge that has rolled slightly in use, which is why a strop can revive a tool that feels dull without any stone being touched.

What you'll need

• Strip of leather, or flat MDF, or a hardwood block
• Honing compound — a bar of chromium oxide or a fine polishing compound
• Flat backing board for the leather
• Contact adhesive or double-sided tape (optional)

Step by step

1. Make a strop.Glue a strip of thick leather, rough side up, to a flat piece of timber or MDF. Or skip the leather entirely and use a flat piece of bare MDF, which works remarkably well and is what many people prefer for woodworking tools because it is harder and rounds the edge less.
2. Charge it with compound.Rub a bar of honing compound — green chromium oxide is the common choice — across the surface until it is coloured evenly. It takes very little. Recharge occasionally when the strop looks grey with steel rather than green.
3. Lay the bevel flat on the strop.Put the bevel down so it sits flat against the surface, exactly as it sat on the stone. Do not lift the back of the blade, and do not raise the angle.
4. Pull, never push.Draw the blade backwards, spine first, away from the cutting edge. Pushing edge-first cuts into the strop and, worse, rolls the edge over. This is the only rule that really matters.
5. Use light pressure.The weight of the blade plus a little. Pressing hard makes leather compress and dome up around the edge, which rounds the very tip — the opposite of what you want. This is why a hard strop like MDF is more forgiving.
6. Alternate bevel and back.Ten to twenty strokes on the bevel, then a few with the back flat on the strop, and repeat once. The burr breaks away rather than folding back and forth.
7. Check the burr has gone.Draw a thumbnail lightly across the back of the edge. Nothing should catch. Then test the edge — it should pare end grain cleanly and slice paper without tearing.
8. Strop during work, not only at the end.A dozen strokes on a strop every twenty minutes keeps a chisel or a plane iron sharp for hours and delays going back to the stones. Carving and paring tools are kept sharp almost entirely on the strop.
9. Know when stropping will not save you.Stropping refines and realigns an edge; it does not remove metal in any quantity. A chipped, rounded or genuinely worn edge needs a stone or a grinder.

Tips

• A charged MDF strop is the cheapest sharpening upgrade there is and makes an immediate difference to how tools feel.
• Keep one side of a double strop uncharged for a final polish, or keep two strops with different compounds — coarser first, then fine.
• Wrap the strop or store it face down; grit landing on a charged strop gets dragged straight into the edge you are polishing.
• The same idea works on a razor, on carving tools, on a knife and on secateurs. It is the most transferable sharpening skill there is.

Common mistakes

• Stropping edge-first — It cuts into the strop and rolls the very edge over, so the tool comes off the strop duller than it went on.
• Pressing hard on a soft leather strop — The leather deforms up around the edge and rounds it, producing a blade that feels keen on paper and will not pare end grain.
• Lifting the back of the blade — It raises the angle and puts a small blunt facet right at the edge.
• Expecting a strop to fix a blunt tool — Stropping polishes and realigns. A tool that has genuinely lost its edge needs the stones.

Questions people ask