Sharp today, dull tomorrow - is it just me??

Twindog said:
According to Dr. Vadim Kraichuk, who used to be on the forum and who wrote Knife Deburring: Science behind the lasting edge, an edge will quickly start to dull, at least a bit, after sharpening. Part of the issue is oxidation, both carbon and stainless. In stainless steel, the chromium reacts with oxygen to form a chrome-oxide surface layer that prevents further rusting. This layer can reach 20 nm on a polished surface.

I'd guess, the effect would be less on nitrogen steels, such as Vanax. It seems like it to me.

And as Blues said, the burr or even an acute apex edge can bend in the first 8-10 hours as accumulated stresses from grinding are relieved. Same with a wire edge. He said this bending can reduce a BESS score by 20 points.
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It's why I strop my straight razor before every shave.
 
I used to notice this happen years ago, never did figure it out but posts like this do crop up regularly.

Using waxed leather sheaths fixed it for my fixed blade carbon steel knives, and my stainless just stay sharp.

I honestly don't know what happened to change it, used to blame it on being overstropped, but even my machetes and hatchets easily shave armhair after hanging on a hook for a year or more, and they all have been stropped heavily as part of their in use maintenance.
 
If you store them tip down in KY jelly, the bacteria will slide right off the end. Course, then you’ll have a bunch of slippery bacteria...

Parker
 
From what I've seen, it's all about burrs or weak wire edges (which masquerade as a very fine, very sharp edge until they fold over). I used to fret over it, not being aware of what it was in my early days of learning sharpening. And noticed it more when doing so on guided systems. But once I recognized it for what it was, some greater diligence in burr removal (with stropping or not) made all the difference. I haven't seen it since, at least without immediately recognizing it and fixing it on the spot.

SOMETIMES, a new knife will have some very weak & likely heat-damaged steel near the edge. Those ones can drive you crazy with unstable edges, maybe for months, until enough of that weak steel is removed through several sharpening sessions over some time. Then, even those edges will begin to stabilize and behave as they're supposed to.
 
Obsessed with Edges said:
SOMETIMES, a new knife will have some very weak & likely heat-damaged steel near the edge. Those ones can drive you crazy with unstable edges, maybe for months, until enough of that weak steel is removed through several sharpening sessions over some time. Then, even those edges will begin to stabilize and behave as they're supposed to.
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From what I can gather, Outpost 76 on YouTube has a lot to say about this. According to him, you've got to sharpen a new knife several times in order to discover the knife's true potential. He tests new edges, sharpens, then re-tests. Sometimes he re-sharpens and re-tests 6 to 12 times.
 
Twindog said:
According to Dr. Vadim Kraichuk, who used to be on the forum and who wrote Knife Deburring: Science behind the lasting edge, an edge will quickly start to dull, at least a bit, after sharpening. Part of the issue is oxidation, both carbon and stainless.
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garry3 said:
It's why I strop my straight razor before every shave
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I always suspected oxidation. I believe the OP is talking specifically about EXTRA SHARP edges, and I have certainly noticed this phenomenon myself. I strop before each shave too - even though the razor feels sharp during the shave, it feels less sharp a couple of days later - even after cleaning with alcohol.
Am certainly going to try to find a copy of that book...
 
Since I started sharpening a couple of years back I have thought about this many times but always managed to push it off to just imagining it. But you can't just sharpen your chisels, hang them up, lock them in and then expect them to be dauntingly sharp two weeks later. Same goes for the pocket folder, planer blade, kitchen knife...

I used to think that the edge wasn't getting duller but that I was getting sharper, meaning that I've become better at sharpening since last time I felt this edge and that's why I could feel it lacking in sharpness. But just as you say -it sometimes happens over night, and I don't get that much better at sharpening just from sleeping 8 hours.

Could it be that a sharpened material can obtain a very sharp edge even though the crystaline structure of said material does not want to stay organized is such a manner. Therefore the atoms rearrange, not exactly like ice sculptures evaporate even though they are in freezing surroundings, but something of the sorts. I don't know, but something is going down! Anyway, I'm new here so I'm glad you started this thread. I would not have dared to bring this up in fear of being ridiculed and maybe even banned from this prolific forum.

The earth used to be flat.
 
Carbides just want some respect and attention. Is it too much to ask?

The day of anti-carbidism is over...and not a moment too soon, if you ask me. 😂
 
DeadboxHero said:
Wire edge/burr is the biggest culprit.
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I think it's because he's closer to the magnetic pole...the influence upon the edge would require that each night he reorient the blade to mitigate the magnetic effects of the previous night.

earth_dipole_mag_field_anim_sm.gif


🥳
 
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