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

shane45-1911

shane45-1911

Joined
Aug 5, 2001
Messages
4,306
So.....I sharpen a knife and fingertip check, thumbnail drag test and arm-hair slice - check. Wicked sharp. Put the knife away. Check it the next day for sharpness (because that's my OCD kicking in!) and the damn thing doesn't feel as sharp as when I put it away.

I swear there are gremlins that eat away at the fine edges of knives while I am sleeping.

(Not looking for sharpening tips, I know how to sharpen a knife either freehand or with my Edge Pro Apex. Just making an observation that baffles me!)
 
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Is it a carbon steel blade? I notice that when I work a fine edge up on my carbon blades, especially softer steel, that 3veb sheathing the knife tends to knock that gnat-hair sharpness down a bit. I think I may have an ultra fine bur worked up that will pop hair but deform under any real stress.

In short, the sharpening gremlins visit my house too.
 
shane45-1911 said:
So.....I sharpen a knife or 3 and fingertip check and thumbnail drag test - check. Wicked sharp. Put the knife away. Check it the next day for sharpness (because that's my OCD kicking in!) and the damn thing doesn't feel as sharp as when I put it away.

I swear there are gremlins that eat away at the fine edges of knives while I am sleeping.

(Not looking for sharpening tips, I know how to sharpen a knife either freehand or with my Edge Pro Apex. Just making an observation that baffles me!)
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Jdavis882 had a video on this, only he said that one of his knives "healed itself" and was sharper the next day.

Since I choose not to be associated with crazy talk, I'm going to pretend that I didn't read this thread. :D
 
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I have an older 1095 Camillus AFPK that was used as my field knife. I noticed a similar problem where over time and w/o use the sharpness level would drop. At one point before putting it away I smeared some petroluem jelly over the edge and the problem went away. My conclusion was the steel was oxidizing naturally, albeit slowly, and it wouldn’t take much to erode the thin apex and lose the edge. But it didn’t happen overnight, so maybe this doesn't apply here.
 
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.
 
shane45-1911 said:
So.....I sharpen a knife or 3 and fingertip check and thumbnail drag test - check. Wicked sharp. Put the knife away. Check it the next day for sharpness (because that's my OCD kicking in!) and the damn thing doesn't feel as sharp as when I put it away.

I swear there are gremlins that eat away at the fine edges of knives while I am sleeping.

(Not looking for sharpening tips, I know how to sharpen a knife either freehand or with my Edge Pro Apex. Just making an observation that baffles me!)
Click to expand...
Ok, you caught me. I promise to stop sneaking into your house and using your knives...
 
And two new species of bacteria were responsible, according to a study the researchers published last week in Nature . The bacteria, tentatively christened Candidatus Manganitrophus nodulliformans and Ramlicbacter lithotrophicus, can borrow electrons from metals like manganese and use them as fuel for growth.Jul 21, 2020 😧
 
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If the steel is relatively soft, or a low-alloy stainless steel -> likely a ductile, thin burr folding over. Even the thumbnail drag test can make that happen, sometimes. This is the most likely, from what I've seen. And sharpening these soft, ductile steels on a guided setup can produce some ridiculously wide, but very thin & flimsy burrs. That's because the angle doesn't change on a guided sharpener. And with steels like this, sometimes it's necessary to elevate the angle a bit to break or cut off the flimsy burrs, OR to simply fold them, so it's easier to see when they're there.

If the knife is a sheathed fixed blade -> edge is being dulled by contact inside a hard sheath (kydex, etc.). Might be compounded by a soft, folding burr as above.

If the knife is a folder, like a traditional slipjoint or lockback, check to make sure the edge isn't contacting the backspring/lockbar. That usually affects only a small segment of the blade's edge, but it's still worth checking.

Test sharpness by slicing fine paper, then by lightly draw-cutting into some hardwood, then slice the paper again. Any weak burrs or 'foil edges' won't survive that treatment. So, if the edge dulls immediately in doing so, you know what's happening. If it continues to cut with hair-popping sharpness, you KNOW the edge will hold up and you're good to go. ;)
 
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Nope, no wire edges or burrs. And I don't keep my fixed blades in their sheaths. It's gremlins, I tell ya!!! :p

Perhaps my hands ARE softer the next day, lol.

Thanks for the laughs. Admittedly, my original post was rather tongue-in-cheek, but it is an interesting phenomenon. I never thought about the oxidation factor or bending edges. Or bacteria!!!!! :oops:
 
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shane45-1911 said:
Nope, no wire edges or burrs. And I don't keep my fixed blades in their sheaths. It's gremlins, I tell ya!!! :p
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Ohh, I forgot and then remembered.

rZuZU8K.jpg


You have to store knives tip up, so the Carbides don't switch direction.
 
shane45-1911 said:
So.....I sharpen a knife and fingertip check, thumbnail drag test and arm-hair slice - check. Wicked sharp. Put the knife away. Check it the next day for sharpness (because that's my OCD kicking in!) and the damn thing doesn't feel as sharp as when I put it away.

I swear there are gremlins that eat away at the fine edges of knives while I am sleeping.

(Not looking for sharpening tips, I know how to sharpen a knife either freehand or with my Edge Pro Apex. Just making an observation that baffles me!)
Click to expand...

I don't remember ever seeing anything like that.
 
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