Unused Edge: How long to degrade?

singularity35

singularity35

Joined
Mar 1, 2010
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Just curious as to what you guys think. If you carry a knife and never use it will the edge degrade(get duller) over a period of time? If so what time frame can we expect for the degradation?
 
I've noticed this too, I just blame it on gramlins though. :D
I'm not sure of any way, other than corrosion, that a knife could just get dull all by itself. Maybe someone else could clue me in though, so I can stop yelling at Gizmo. :p
humming-gizmo.jpg
 
Could be a number of things.

Oxidation would probably be my number one reason. Even the air has moisture, and oxygen is a rather powerful reducing agent.

Another possibility is maybe you used it, and didn't completely clean the blade off. I've cut lemons with my knife and put it away with the juice still on the edge before.

The one I think is least likely is entropy. Molecules/atoms are not 100% stable; in fact your knives are vibrating at a frequency that corresponds to the ambient temperature.
 
GWashington1732 said:
I've noticed this too, I just blame it on gramlins though. :D
I'm not sure of any way, other than corrosion, that a knife could just get dull all by itself. Maybe someone else could clue me in though, so I can stop yelling at Gizmo. :p
humming-gizmo.jpg
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Well if gizmo's there, whose dulling my knives then?
 
Cynic2701 said:
Could be a number of things.

Oxidation would probably be my number one reason. Even the air has moisture, and oxygen is a rather powerful reducing agent.

Another possibility is maybe you used it, and didn't completely clean the blade off. I've cut lemons with my knife and put it away with the juice still on the edge before.

The one I think is least likely is entropy. Molecules/atoms are not 100% stable; in fact your knives are vibrating at a frequency that corresponds to the ambient temperature.
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I didn't use mine at all. After about a month I couldn't whittle hair. It was just in my pocket and I didn't even touch the edge.
 
singularity35 said:
I didn't use mine at all. After about a month I couldn't whittle hair. It was just in my pocket and I didn't even touch the edge.
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I might have an explanation that doesn't involve gremlins. Lint and dirt, if it was in your pocket, then there's always a chance that dirt could have gotten in there with it, it's inevitable. Add a little lint to that, and you get little tiny sheets of sandpaper, and that could dull a knife.
 
My knives do the same thing (dull for no reason) and others remain razor sharp. Very odd indeed.
 
GWashington1732 said:
I might have an explanation that doesn't involve gremlins. Lint and dirt, if it was in your pocket, then there's always a chance that dirt could have gotten in there with it, it's inevitable. Add a little lint to that, and you get little tiny sheets of sandpaper, and that could dull a knife.
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Hhhhm, I think you may have the answer there.
 
sorry, I'm not buying it... I've opened (and used) old boxes of razor blades that were over 25 yrs old... not the least bit dull
 
I noticed this too a while ago when I would pick up a knife that I put away as my "uber scary sharp exacto knife", but then when I went to actually use it, it wasn't as sharp as I remembered.

I asked around, and a few of the theories that have been mentioned here with oxidation and "entropy" or decay, but neither of these seemed very likely. I recalled reading something in John Juranitch's book about steeling though, and he said that butchers should steel their knives before cutting because over time the microserrations on the edge of the knife will start to kind of "fold" outward. So according to him, it's better to steel before cutting than after because of that.

I got over it myself, but one thing that you could do to test the oxidation theory is to coat the blade with something like mineral oil or wax. The edge shouldn't oxidize then, but I didn't really care enough to get into an elaborate testing like that.

Personally I think that it has more to do with other variables, how you test the knife, etc. I mean, if the knife push cuts phone book paper one day three months ago, but just tears it on this particular day, does this mean the edge changed or the humidity of the paper changed? Same thing can be said for shaving hair, or cutting pretty much anything else. One thing I started to realize when cutting plastic bags up was that I thought my knife got "duller" from the beginning of the summer into mid-summer; in reality, plastic bags just get really hard to cut when it's 100F or more outside. Within a week the temperatures dropped, and my knife felt "sharper" without me doing a thing.
 
george65 said:
sorry, I'm not buying it... I've opened (and used) old boxes of razor blades that were over 25 yrs old... not the least bit dull
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No oxidation, no dulling. Your old razor blades had multiple layers of protection against oxidation. Take one out of the box, unwrap it, degrease it, wait a few weeks, and it'll be noticeably less sharp even in the absence of visible corrosion,
 
Leftoverdj said:
No oxidation, no dulling. Your old razor blades had multiple layers of protection against oxidation. Take one out of the box, unwrap it, degrease it, wait a few weeks, and it'll be noticeably less sharp even in the absence of visible corrosion,
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no oil on these... some have been sitting out for years... i still don't buy it.
 
Mmmh. Scientifically I can only see corrosion as a dulling agent, if the knife was simply put in a box, without anything touching it. Not entropy or diffusion at this scale.
 
singularity35 said:
I didn't use mine at all. After about a month I couldn't whittle hair. It was just in my pocket and I didn't even touch the edge.
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Maybe abrasion from pocket grit. I have a dedicated SD blade that is used for nothing else and I have to say I have never found it to dull at all, but it doesn't live in a pocket.
 
i bought a schrade melon tester from a lady in her 50s & the knife had belonged to her father. was made in 40s or 50s & had cream celluloid handles. i opened it up & it would shave hair. sometimes an unused knife never gets dull..
dennis
 
Never. Any dulling without usage was a figment of your imagination, the knives were never that sharp to begin with.
 
I have a few SAKS that seem to get duller just by me looking at them. Never have been able to figure that one out.
 
I have my fathers schrade knife from the 70s, 1095 steel, no grease or coating on the knife at all sitting in a leather sheath, and the sucker still shaves no problem.
 
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