Knives lose sharpness just sitting

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May 1, 2016
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This negligible deterioration is detected by magical bess tester only, but to some gun people it offers a huge explanation on why their sharp knives just don't stay that way for long. Never mind their sharpening.
 

Pilsner

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Oct 28, 2017
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It’s also quite common for people to put a wire edge on, I’ve done it myself. This creates a seemingly inexplicable phenomenon to someone ignorant about wire edges, that was also me by the way. ‘It just seems to dull doing nothing!’ is as good an incorrect explanation as any other. ;)
 

Twindog

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I thought I saw in the OPs post that the dulling of the blade while idle was explicitly not due to corrosion but some magical properties. I think the reality is that corrosion and thermal property changes might effect the edge's exact sharpness. This all still has no effect on the practical use and cutting that anyone would notice.

You're right, he did say that. I was commenting just on corrosion, not supporting the OP's statement. I see this topic discussed periodically on Bladeforums and on numerous places around the web. Except for the BESS guy, I don't see much in the way of actual science.

I live in the rainforest about a mile and a half upstream from the ocean. Things here corrode fast, which is why I mostly use stainless steel. So, for example, I can't leave M4 steel in a leather sheath for months because it will pit, even if lightly coated with oil when I put it away.

I took a 15X loupe to the edge of my 1095 chef's knife, which has no rust on the blade. But the edge does have rust and heavy patina in many places. Hard to believe that rust has no effect.
 
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You're right, he did say that. I was commenting just on corrosion, not supporting the OP's statement. I see this topic discussed periodically on Bladeforums and on numerous places around the web. Except for the BESS guy, I don't see much in the way of actual science.

I live in the rainforest about a mile and a half upstream from the ocean. Things here corrode fast, which is why I mostly use stainless steel. So, for example, I can't leave M4 steel in a leather sheath for months because it will pit, even if lightly coated with oil when I put it away.

I took a 15X loupe to the edge of my 1095 chef's knife, which has no rust on the blade. But the edge does have rust and heavy patina in many places. Hard to believe that rust has no effect.
Of course rust can have an effect. That's not what OP is talking about.
 

Twindog

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So what about the BESS guy who found that razor blades go from 50 BESS to 70 BESS after sitting out over night?

I'm not sold on BESS, but that particular tester seems to think that he can reliably demonstrate a small loss of sharpness from leaving a razor blade out overnight. That's the only science-based evidence that has been posted in this thread.
 

Twindog

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I did some reading over on the BESS forums, where there seems to be a lot of support for the notion that knife edges do lose some sharpness after sitting overnight. There are two proposed causes:

1) After sharpening or grinding, even stainless steels get a fresh oxidation coating. With stainless steels, the coating is about 20-50nm and it then stops. Put this oxidation coating over an edge sharpened to 0.5 microns, and you get a small, but noticeable dulling effect.
https://link.springer.com/article/10.1007/BF01045379

50nm is 0.05 microns, so the effect would be very small.

2) If a burr is left on the edge and straightened by stropping, the burr, which was forced to stand upright from a leaning position, will fall back somewhat toward its original folded position after sitting overnight, causing a loss of sharpness.
http://www.edgeonup.com/KN100_Operating_Manual.pdf (see pages 39-42)

This seems to be edgy stuff, and I'm not sure how to take it; but people with BESS testers say they can reliably produced these effects.

Some discussion:
http://www.bessex.com/forum/showthread.php?tid=229

http://bessex.com/forum/showthread.php?tid=356&highlight=corrosion
 
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I did some reading over on the BESS forums, where there seems to be a lot of support for the notion that knife edges do lose some sharpness after sitting overnight.

The people over at the BESS forums play with levels of sharpness many people won’t get.

A guy with a pull through sharpener worrying about this loss of sharpness is like a guy putting a spoiler on his corolla to increase downforce for cornering.

EDIT: your point is well taken. There are a lot of people here making fun of the gun forum guys for believing something they know nothing about. But the people here likely don’t know anything about it either.
 
Last edited:
Joined
Jan 26, 2012
Messages
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I did some reading over on the BESS forums, where there seems to be a lot of support for the notion that knife edges do lose some sharpness after sitting overnight. There are two proposed causes:

1) After sharpening or grinding, even stainless steels get a fresh oxidation coating. With stainless steels, the coating is about 20-50nm and it then stops. Put this oxidation coating over an edge sharpened to 0.5 microns, and you get a small, but noticeable dulling effect.
https://link.springer.com/article/10.1007/BF01045379

50nm is 0.05 microns, so the effect would be very small.

2) If a burr is left on the edge and straightened by stropping, the burr, which was forced to stand upright from a leaning position, will fall back somewhat toward its original folded position after sitting overnight, causing a loss of sharpness.
http://www.edgeonup.com/KN100_Operating_Manual.pdf (see pages 39-42)

This seems to be edgy stuff, and I'm not sure how to take it; but people with BESS testers say they can reliably produced these effects.

Some discussion:
http://www.bessex.com/forum/showthread.php?tid=229

http://bessex.com/forum/showthread.php?tid=356&highlight=corrosion
Neither one of those things seems to be what the op is talking about. Both of what you mention I'm sure is true. He's proposing the steel relaxes and loses half its sharpness over night which simply isn't true.
 
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The people over at the BESS forums play with levels of sharpness many people won’t get.

A guy with a pull through sharpener worrying about this loss of sharpness is like a guy putting a spoiler on his corolla to increase downforce for cornering.

EDIT: your point is well taken. There are a lot of people here making fun of the gun forum guys for believing something they know nothing about. But the people here likely don’t know anything about it either.
But we do know what a sharp knife for use is and we do know that the stuff in the op isn't true and doesn't matter a lick for the end knife user.
 
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I don't recall the name of the author, but there was a thesis on sharpening and stropping knives that talked about "relaxing" steel, and stuff like that. It involved power stropping, and other such things. It got referenced a lot by straight razor users who talked about razors needing a day to rest after honing and all sorts of other stuff. Of course the thesis didn't cover edge geometry or even honing/stropping methods suited to straights, so it got shot down a lot, but would not die. From memory there were exerts online, but one guy on the old SRP had a full copy. I find it interesting that this same thing now comes from a different direction, using the same hocus-pocus, and applied to knives instead of razors. Proof that pseudoscience still uses some science.
 
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All of my knives (Gerber "mystery steel" included) go back into their drawers shaving sharp, and weeks later, they come back out still shaving sharp. If they do dull by just sitting, it's too minor to notice.
 

thebrain

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Dec 12, 2007
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The suppositions seem like science but lack far too much actual science. They even mention actual scientist having found that over great periods of time the oxidation layer being much thinner than they are saying in their own findings.
 

Sonnydaze

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Whether reality-based or pure fiction, it has zero relevance for my use of a blade.
 
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