knifeopedia
Edge Maintenance
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Contrary to popular belief, when a once-sharp knife starts feeling dull, it often doesn't need full sharpening. In most cases, the sharpness can be restored with much less effort, and here’s why and how.
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Imagine you're cutting through a tough pumpkin with a 24 cm chef's knife, sharpened to a razor-thin edge at an included angle of 15°, made from AEB-L steel at HRC 62. You apply significant pressure to make it through the pumpkin, likely hitting the cutting board hard. This impact can cause the edge to roll or bend (see pic. below), so that the sharpness you're so proud of disappears.
In such a case, it's not that the edge is worn down—it's simply misaligned. The edge is still there, just bent out of place. So all you need to do to restore the sharpness is to realign the edge to its proper angle.
When it comes to edge maintenance, terms like honing and stropping can often cause confusion, especially since they’re used interchangeably in different contexts. Let’s clear things up a bit.
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Stropping traditionally refers to the process of further refining and smoothing the edge after sharpening. This involves removing any residues, burrs, and micro-scratches, giving the blade a polished finish. But stropping can also realign a bent edge.
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Honing by name also implies refining of the cutting edge. But since it's usually done with honing rods, it does little to improve the edge of a newly and nicely sharpened knife. The main purpose of using a honing rod is to straighten/realign the edge and restore the sharpness of the knife. But depending on the coarseness of the rod, it will take material off the edge and thus sharpen the knife.
Now that we’ve covered stropping and honing as part of the sharpening process, let's focus on how to straighten a bent edge.
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Straightening
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There are several tools you can use to straighten or realign a bent edge:
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Stropping block:
usually a strip of leather attached to a hard, flat base
Newspaper:
at least 10 pages of a newspaper put flat on a table
High grit whetstone:
3000 grit and above
Honing rod:
with very smooth or no ridges
No matter which tool you use, the key is to move the knife across the surface at a slightly wider angle than the cutting edge. If the angle is too shallow, the blade will just glide over the sharpening tool. Gradually raise the angle until you feel it grip—that’s when you’ve found the right angle.
When using leather or newspaper, it’s crucial to only pull, not push, the blade. Begin with a few firm strokes on each side, gradually reducing the number and lightening the pressure as you finish. When done correctly, this technique can quickly bring back your knife’s sharpness without needing a full sharpening.
Microbevelling
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We’ve already covered how thin edges, while sharper, are more susceptible to chipping and rolling. Even hard steel, when sharpened to an acute angle, can roll if it hits a hard cutting board (like bamboo) with force. However, there is a way to mitigate this issue — by adding a microbevel.
A microbevel is essentially a secondary bevel added to the very tip of your cutting edge at a slightly wider angle. This subtle addition strengthens the ultra-thin edge at a microscopic level. In cutting performance tests, while a microbevel might cause a small reduction in initial sharpness, the trade-off is a significantly longer-lasting sharpness.
A microbevel is applied using the finest grit of your sharpening tool, with a few gentle swipes on each side at a slightly raised angle. If you’ve sharpened your edge to an included angle of about 20°, the microbevel should be added at around 30°.
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Here a link to a good video, explaining how to apply a microlevel:
Grinding a microbevel on a new knife
In the knife community, microbevels are a topic of debate, as their effectiveness can vary depending on the type of steel, edge geometry, and sharpening technique. However, if you've sharpened your knife to a razor-sharp edge only to find the sharpness dulls within a day or two of regular use, trying a microbevel might be the solution.
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Moreover, adding a microbevel is particularly recommended when the edge becomes prone to chipping at acute angles. This is often a concern with blades made from steel that has a high carbide volume or large primary carbides.