Spontaneous Loss Of Edge

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phil briscoe

Joined
Sep 2, 2008
Messages
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I have the impression that a knife edge can lose its sharpness just sitting on a shelf with no contact with anything, no rust or corrosion. I have asked around with no conclusion. Is there anything to this? Can thin steel move on its own, and is that what a sharpening steel is doing, in reverse?
 
Hi, welcome to the forums. Um, no. A knife will not lose its edge if it's just sitting around. A sharp knife will stay that way indefinitely, unless it is used or it begins to corrode.
 
I have noticed a couple things......after a rain storm or an increase in humidity......knives that sliced paper might not anymore. More humid paper means the edge SEEMS more dull.
 
moonwilson said:
Hi, welcome to the forums. Um, no. A knife will not lose its edge if it's just sitting around. A sharp knife will stay that way indefinitely, unless it is used or it begins to corrode.
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I agree, conditions may make the knife act like it has dulled, but unless there has been layer of corrosion building up, it will remain sharp indefinatly.
 
I have noticed on knives on display over a period of several months knives seem to lose that very sharp edge. I think MMMOTORCYCLE may have the answer with humidity. My observations come from a knifenut over some fifty years. My first pocketknife was given to me by my Grandfather when I was five. Recently, I had a Dozier folder I had left open on my computer table for several weeks and when I got back to it I noticed a slight dulling of the blade.

RKH
 
I wondered the same thing about knives magically losing their edge one day and then getting sharper or duller the next. I've come to the conclusion that since my primary test for a blade is to run my finger perpendicular to the blade, the difference in moisture on my fingertips are what is causing the sensory difference from day to day...
 
Why couldn't the edge of as carbon steel blade suffer from oxidation from the air along the very finest portion of the edge? It wouldn't take much to weaken the finest point of an edge.

For that matter stainless could be affected as well, since its only stainless because of the passivation layer that forms on the surface. Couldn't an edge be degraded by the same effect over time?
 
I have noticed knives getting slightly duller just by laying around. I have read posts from others noticing the same thing. I've seen it referred to as "micro oxidation".


Not sure if any of this is true, just that I have noticed it. Just a slight dulling and the knife has to be very sharp to notice the differance.
 
I have read that a carbon steel knife will lose it's edge over time laying in a drawer by just corrosion on the edge exposed to air. I first read this in The Practical Book of Knives by Ken Warner. Also, I have read articles by Knifewriter Steven Dick about carbon steel versus stainless steel blades how in canning tomotoes and fruit that a carbon edge would lose it edge from the acidity of the fruit while the stainless would keep on cutting due to the Chrominuin content of the steel rather than better edge holding.

RKH
 
elkins45 said:
Why couldn't the edge of as carbon steel blade suffer from oxidation from the air along the very finest portion of the edge? It wouldn't take much to weaken the finest point of an edge.

For that matter stainless could be affected as well, since its only stainless because of the passivation layer that forms on the surface. Couldn't an edge be degraded by the same effect over time?
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you got the correct answer!:thumbup:
 
I don't think that a sharp knife can get noticeably dull from just setting on a shelf.
 
I've seen this happen with knives myself, but this was ages ago, before I wiped down blades with a Tuf-Cloth when storing them for a while. It seems like the edge (which has thousands of microscratches from sharpening on stones) can build up a bit of oxidization. Not enough to see, but enough to cause the knife to feel dull. Usually all it takes is a bit of stropping on cardboard to restore the razor edge.
 
mmmotorcycle said:
I have noticed a couple things......after a rain storm or an increase in humidity......knives that sliced paper might not anymore. More humid paper means the edge SEEMS more dull.
Click to expand...

The grain direction of the paper may also be a factor
 
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