Knife getting dull from sitting in pocket?

T

tommyg805

Joined
Sep 5, 2010
Messages
93
My Spyderco Sage seems to get dull even though i havent really used it since i sharpened it about three weeks ago. It still cuts paper (sloppily), but when I sharpened it, it was stupid sharp. It's my office carry, so I hardly ever use it (once or twice/week) so I'm perplexed as to why this happens. Is it all in my head? Or do others experience this phenomenon as well? What do you think is the cause of this?
 
Do you have anything else in your pocket that could be hitting the edge through the open back? Corrosion can also dull an edge, but that's not likely with s30v.
 
tommyg805 said:
My Spyderco Sage seems to get dull even though i havent really used it since i sharpened it about three weeks ago. It still cuts paper (sloppily), but when I sharpened it, it was stupid sharp. It's my office carry, so I hardly ever use it (once or twice/week) so I'm perplexed as to why this happens. Is it all in my head? Or do others experience this phenomenon as well? What do you think is the cause of this?
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this is the second time i have read something about the edge someone's spyderco dulling just from carrying it...

Nikkogi said:
The VG10 serrated knives are pretty good. I have not had good experiences with the H1 Pac Salt serrations though. I had it in my waistband while doing some surfcasting this summer and the edge totally dulled on me without cutting anything. It was just from the salt water.
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I've carried even POS knives with no-name steel that didn't "dull from carrying." I think there is more to it than that. I agree that the Sage probably had a wire edge that broke off during light use, giving the appearance of sharpness at first and seeming like the blade dulled instantly or just from non use...as for the Pac Salt in the quoted post, I have no idea...there isn't enough information given.
 
It happens for me with a knife made from Hitachi White steel. It dulls a bit overnight. I attribute it to oxidation as it's the easiest corroding steel I've ever used. It can happen with others depending on the steel and the finish I've given the edge.

I have some knives that can shave hairs when I put them up and a couple of weeks later they will barely scrape hairs off my arm after sitting with no use.

With VG10 and S30V finished and stropped if it's happening it's so slow I don't notice and can't tell a difference.
 
ok weve had all the complicated answers, i think the simple answer is either you didnt have it as sharp as you thought going into your pocket, or you used it more than you remembered. any of mine can ride around in my pocket for quite a long time and see only occasional use and still maintain there edge. i can also say ive probubly forgot to sharpen from time to time and was left using a knife that wasnt as sharp as i would of liked. i didnt try placing it under a pyramid though maybe you should.
 
Tsujigiri said:
Do you have anything else in your pocket that could be hitting the edge through the open back?
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^This is what happened to me.^

I couldn't figure out how the S30V knife I kept clipped to the inside of my pocket was getting quite dull without even using it. -Finally figured out that my car key was just the right shape to slip through the open handle scales and come in direct contact with the razor edge of my knife. resulting in a dulled, and visibly damaged edge!
 
i had a knife that was the same way. i could have it shaving sharp when i put it in my pocket and a week later check the edge and it would be dull. i gave it to a friend to carry for a while. he had no problems with it so i sold it to him. try carrying another knife and see what happens to it.
 
S30V has a unique reputation, in that it will initially take a razor-like edge (a.k.a., 'stupid sharp'), but that fine edge chips off quickly, doing relatively simple things like slicing paper, etc. It leaves behind a somewhat less sharp, but toothy edge remaining. That toothy edge lasts a good while, and is durable for hard use, such as cutting cardboard. I think the key in sharpening it, is to make sure the bevel is as pure as possible, with the expectation that the finest part of the edge will come off quickly. Most of the real work will be done with what's left behind that fine edge.

There've been a few discussions over in the Maintenance forum on just this subject.
 
I've thought about this often. I live in florida, and have a drawer full of knives that never seem as sharp as they ought to when I pull them out to fool around.

The most obvious example is a full convex custom that I use as a letter opener. Hand forged, I think from 5160, it sits on my desk. After a while of non-use it just doesn't seem as sharp as it should, a few passes on a strop and it's popping hairs again.

So I don't have any science to back it up, but count my anecdotal evidence in the pile of atmospheric edge corrosion.
 
bada61265 said:
ok weve had all the complicated answers, i think the simple answer is either you didnt have it as sharp as you thought going into your pocket, or you used it more than you remembered. any of mine can ride around in my pocket for quite a long time and see only occasional use and still maintain there edge. i can also say ive probubly forgot to sharpen from time to time and was left using a knife that wasnt as sharp as i would of liked. i didnt try placing it under a pyramid though maybe you should.
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Nothing like simplistic answers :rolleyes: to non-complicated questions :D
 
I don't carry anything else in a pocket I have a knife in,except maybe chapstick.I can't believe that it has'nt been mentioned yet,but it could be a wire edge.;)
 
In my case it's definitely not my imagination. Nor is it being dulled by anything as it's in a box put away.

It happens to me with carbon/ low alloy steels. My VG 10 Endura, or El max Kershaw can sit a month and still shave hairs better than a commercial razor provided that's how I left it.

White steel can dull overnight noticeably. Super blue might take twice as long, but it's still relatively short compared to, say, 3V, which can sit a month with no real difference.

I treat all of my knives the same way making sure they are cleaned of anything salty or acidic, even fingerprints. After they are clean and dry I use silicone to seal the steel. I have no noticeable rust on any of my blades using this method. Even the edge gets treated.

With Hitachi white steel it happens fast enough to make the conclusion that the level of finish and quality of applied edge does change the speed of dulling. Lower grit finishes, or edge finishes where I skipped a grit or two in sharpening to even the same grit finish
dull quicker than a high or very high quality mirror type finish.
 
From what I have seen it can be caused by a few things. The corrosion of the edge is real but I think its far more common when the edge has a small remaining burr or fin of metal left on the edge. I have left a carbon steel blade that was 100% burr free sit untouched and it took 3+ months before the edge started to be affected. Letting a blade sit for a day after sharpening on stones is one way I check how well I formed the edge. If the apex was not met or a burr/fin was remaining the edge will loose sharpness and have a slight burr the next day.

My last thought on it is a bit more scientific and relates to decompression of the steel. When sharpening on a hard stone the pressure you use can come back to bite you once the sharpening is done. Because the contact point is so small even a little pressure is a lot on the edge bevel. When your done sharpening and pressure is no longer being applied the steel starts to "relax" or decompress. I don't know if the apex actually grows wider but the effect is similar to edge corrosion from a burr/fin.

Because of all the possibilities I've got into the habit of letting a blade sit for a day then re-doing the final sharpening step. For me this has cleared up all problems of next day dulling and consistently given me sharper edges than what the knife had before sitting.
 
Are any of you guys wearing those copper bracelets that are supposed to give you energy? Those could be the culprit.
 
Knifenut1013, Thanks for the response and info. I've never looked at a magnified picture of my edge before or after while thinking about this subject. It's in a "safe" place somewhere that's so safe I can't find it.

The best way I can describe it is when testing it for "bite" on my thumbnail it loses that bite. Freshening up the edge or giving it an old fashioned steeling will bring the bite back to some extent if it's just a short amount of time. If it's a month or more resharpening is needed.

As I stated I don't really notice this happening with my stainless blades.

I do sometimes use too much pressure when sharpening and do my best work when paying attention , and not hurrying or applying more pressure than needed.

I do sharpen freehand so it's in no way going to compare to a really good Edge pro, or DMT angle guide system sharpened knife.

I also usually keep the steels to DMT red, or green mostly after going through years of experiments with up to 8, 000 grit and above at times. I do strop on leather with various diamond grits, sometimes on 2, 000 grit sandpaper if keeping it coarse and just knocking off a burr.

Thanks, Joe
 
"It's in a "safe" place somewhere that's so safe I can't find it."

That funny :)

I've never had it happen with low alloy stainless either but S30V S90V elmax and others that (correct me if I'm wrong) have a high percentage of carbon are the blades it seems to happen most with. Try re-touching on the EF stone with almost no pressure the next day then strop, it should help.

When it gets down below the 1200 grit I think the variables from the larger "teeth" play a larger role. Haven't tested that yet though so its nothing more than a educated guess.

Try using your fingers more to feel the edge, if you let the edge lightly bite your finger tips it helps to better feel the edge on a smaller scale. Its not just putting your finger on the edge but resting your finger on the edge then sliding it in one direction. Yes your cutting yourself so don't go too far or the doctor will see you shortly ;)
 
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