Double burr-like edge on paring knives that have been used a lot after sharpening and burr removal

[Another Shepherd]

I usually sharpen kitchen knives and cheap steel on a Work Sharp Ken Onion--works fast, works great. I use a leather strop to remove any remaining burr, after which the blades measure somewhere between BESS 100 and 200.

I recently got a Hapstone and the fancy new Work Sharp Pro Precision Adjust to try out the magnetic tables on knives with narrow blades. I noticed that each of three Victorinox paring knives, which had been used a lot since they were sharpened, had what felt like a strong burr on each side of the blade. Two Misen paring knives also had this double "burr". These five knives all measured between BESS 400 and 900. Three other plain-edge paring knives were OK, no burrs. Likewise, several larger knives were OK.

When sharpening, SOP is to begin with a coarse or medium stone/plate/rod and grind lightly until you feel a burr. That will not work if the blades have "burrs" on both side to begin with.

So, on one of the Victorinox knives, I tried my usual methods for removing burrs: plain leather strop (100 strokes, no effect), KnifeJoy strop (100 strokes, no effect), rough end of a 2x4 (20 strokes, no effect), wooden dowel to push the burr to one side (no effect), 100 strokes at at a steeper angle on a fine plate (no effect), 100 strokes at at a steeper angle on a medium plate (no effect), 40 strokes at a steeper angle on a coarse plate--finally some progress! After 80 strokes on the coarse plate, the double "burr" was gone.

I notice that all the knives with double "burrs", and only those knives, are the ones that my wife uses as steak knives. I wonder if cutting on a hard plate, rather than a cutting board, could cause this double "burr" effect.

Any ideas?

 

[Obsessed with Edges]

That double burr is what I refer to as mushrooming of the apex. In cross-section, the thin edge would look like a 'T' more or less. Goes beyond simple flattening of the apex and instead forces the steel perpendicularly outward on both sides of the apex. And no surprise that the knives with this issue were used as steak knives. If cutting on a ceramic plate, such relatively soft, ductile steels, as with the Victorinox blades and many others, will do that.

My Dad used to halve & quarter an apple on the ceramic tile countertop, using the paring knife from his old Chicago Cutlery block set. He'd press real hard to get the cut started, then it'd smack hard & loud into the ceramic tile under the apple. And it always resulted in a mushroomed apex in the forward belly portion of the edge.

Such damage won't be fixed by any stropping method, whether it be on leather, wood, etc. The 'burr' effect on each side of the apex is just too stiff & heavy for that. I generally fix this damage by resetting the edge on a Fine India stone (360-400). Might also be able to 'steel' the edge back into something resembling a functional edge. But, when the steel at the apex is deformed in such a brutal way, I regard it as damaged and permanently weakened and I'll grind it off on a stone and reset the edge.

 

[Another Shepherd]

Might also be able to 'steel' the edge back into something resembling a functional edge. But, when the steel at the apex is deformed in such a brutal way, I regard it as damaged and permanently weakened and I'll grind it off on a stone and reset the edge.

I have a smooth butcher's steel that I had been meaning to try out but never got around to. So I tried it on a Victorinox and it dropped the BESS score from 430 to 180! Of course, there are bound to be various spots along the edge that are still dull; I can feel them clearly when I use the edge of the steel instead of the round, but they feel much less pronounced now. A paring knife doesn't need to be perfect to cut steak.

I am going to try using the steel every time I wash the knives and see what happens.

 

[Obsessed with Edges]

I have a smooth butcher's steel that I had been meaning to try out but never got around to. So I tried it on a Victorinox and it dropped the BESS score from 430 to 180! Of course, there are bound to be various spots along the edge that are still dull; I can feel them clearly when I use the edge of the steel instead of the round, but they feel much less pronounced now. A paring knife doesn't need to be perfect to cut steak.

I am going to try using the steel every time I wash the knives and see what happens.

Steeling works pretty well for knives in these ductile steels, for awhile. I'd think a grooved steel would work better for heavily rolled edges and maybe for the mushroomed edge (I haven't tried it yet, for that) to get it basically functional again. But, within the normal limits for a kitchen steeling rod, these knives can be maintained for some time - maybe a few weeks or months if usage isn't very heavy. Most of the steeling effect is all about realigning the edge - bending it back into shape. After some time, that repeated bending of the steel at the edge will leave it weakened and the edge will become unstable, i.e., moving around a lot in use and making for very erratic cutting behavior. That's the cue to take the edge back to a stone to remove the weakened metal at the edge and regrind the bevels.