Rust on stainless PM steels vs rust on non-stainless PM steels

Had a moment last night. On a very questionable whim I decided to lick (very carefully) each blade. Why? I dunno. But only this morning did it occur to me that I just licked dried sweaty leg steel.
 
spict said:
In so many ways not yet.
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If the heat treat was bad on that steel, or the steel was inherently prone to corrosion, it would have shown some corrosion by now. Unless you can make a cogent counterargument?
 
Does it rust while in the pocket slip??? Leather slips can retain moisture or salts (you sweat on the leather, sweat dries and can leave deposits) or if its not veg tanned, (ie chrome tanned leather), that can cause corrosion as well.
 
Taz said:
Does it rust while in the pocket slip??? Leather slips can retain moisture or salts (you sweat on the leather, sweat dries and can leave deposits) or if its not veg tanned, (ie chrome tanned leather), that can cause corrosion as well.
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I feel safe that's the reason why my S45VN Sebenza rusted. And when I carry that one I give it a weekly oily rag wipe down cleaning on the weekends now. It's a Hitch and Timber brand Buck 110 leather pocket slip. Not sure it it's veg tan or Chrome tan.

From their website: "All of our leather is sourced from American Tanneries. We like waxed full grain leathers with a strong pull up." I feel like it's veg tan only because it has no chemical odor and instead has that glorious fresh leather smell.

No clue on about the Para 3 in S45VN that hadn't been carried in quite a while and had been setting in an open case which also holds several non stainless blades that didn't have any rust on them and the case is kept in my air conditioned bedroom.
 
Even veg tanned leather can soak up salt from sweat, so I am guessing thats why.

The Para rusting is stranger; I wonder if something got on it?

I used my welder in my garage once and a ton of my files near it got super rusty. It was raining and I couldn't weld outside, not doing that again!
 
Larrin

Post in thread 'New Magnacut, stained after first use in kitchen'

David Mary said:
Steel dust is nothing but surface area.
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Steel dust also rapidly oxidizes in air (hence why it is burning). But whatever different mechanisms occur, the particles act as initiation sites for corrosion. In an ideal world it would be a perfect polished surface, and free particles are not that.
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According to Larrin, steel dust is prone to oxidation, so that's why we often point fingers at cross contamination from belts, stones, and strops.
 
Taz said:
Even veg tanned leather can soak up salt from sweat, so I am guessing thats why.
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I do wax the leather to help the leather not absorb sweat any pocket is going to be warm and humid. Or cold steel from the A/C going into a warm pocket could possibly get enough condensation? Either way I would expect better from a stainless steel especially a PM stainless.

Taz said:
The Para rusting is stranger; I wonder if something got on it?
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I find the Spyder logo to be the easiest spot to rust and slicing an apple or other food would likely touch there, but not a spot on it. Add to that the DLC coating at least looked like I had cleaned the blade before putting it away. Not sure how residue would have been on the edge but not the blade coating. This is just chewing the fat, not meaning to sound like I'm disagreeing with the idea. Once again though, I expect better of a PM stainless. I know the SPY27 Manix LW has set a lot longer because try as I might I just cannot force myself to carry that one anymore and there is zero rust on that blade. Or the M4 Para 2 that I'm too chicken to carry.
 
SharpBits said:
Larrin

Post in thread 'New Magnacut, stained after first use in kitchen'

David Mary said:
Steel dust is nothing but surface area.
Click to expand...
Steel dust also rapidly oxidizes in air (hence why it is burning). But whatever different mechanisms occur, the particles act as initiation sites for corrosion. In an ideal world it would be a perfect polished surface, and free particles are not that.
  • Like

According to Larrin, steel dust is prone to oxidation, so that's why we often point fingers at cross contamination from belts, stones, and strops.
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Which is why I intentionally used all these on the leather strop to start this bro science experiment. The leather is still loaded up with black compound and has been used on everything from 1066 to Maxamet. Which it didn't seem to do much with Maxamet but works good enough still with Seki City K390. I do use this strop on pretty much every Case knife since they seem to leave a raw belt burr on every edge so it surely has their 1084, 1095, CS, CV, or whatever else they use. And I'm trying everything to get any of them to reproduce the edge rust again. Short of cutting myself for blood contamination. I do draw some lines in the sand when it comes to crazy. And I did just lick them so I figure that's crazy enough.
 
Maximumbob54 said:
Or cold steel from the A/C going into a warm pocket could possibly get enough condensation? Either way I would expect better from a stainless steel especially a PM stainless.
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I sometimes carry Cruwear down here in hot, humid, and sweaty Florida. No rust or corrosion so far. I never even consider treating stainless with anything to protect the blades as it has never been an issue.
 
Maximumbob54 said:
Which is why I intentionally used all these on the leather strop to start this bro science experiment. The leather is still loaded up with black compound and has been used on everything from 1066 to Maxamet. Which it didn't seem to do much with Maxamet but works good enough still with Seki City K390. I do use this strop on pretty much every Case knife since they seem to leave a raw belt burr on every edge so it surely has their 1084, 1095, CS, CV, or whatever else they use. And I'm trying everything to get any of them to reproduce the edge rust again. Short of cutting myself for blood contamination. I do draw some lines in the sand when it comes to crazy. And I did just lick them so I figure that's crazy enough.
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You certainly have gone above and beyond on trying figure it out. You could try some juice from raw hamburger or similar and see if that provokes the rust demons?
 
SharpBits said:
I sometimes carry Cruwear down here in hot, humid, and sweaty Florida. No rust or corrosion so far. I never even consider treating stainless with anything to protect the blades as it has never been an issue.
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I bought the Para 2 "CruCarta" when that became available to get a sense for why I kept seeing people be so ga-ga about that steel. And I live in SE Georgia where it's pretty much reclaimed swampland between swamps. And like you're saying I too didn't see any rust. But CruWear didn't fishhook me like K390 has.
 
SharpBits said:
You certainly have gone above and beyond on trying figure it out. You could try some juice from raw hamburger or similar and see if that provokes the rust demons?
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The current plan was if I still see nothing Saturday morning I was going to mix up some salt water to spray on them and check back no later than that afternoon. I'm only so willing to risk pitting if anything happens. I could also see grilling some burgers that afternoon.
 
Taz said:
Yeah, temp/humidity changes can do strange things! I am surprised too. I have my edc s90v fixed blade that I carry close to my body. It has some rust flecks on it near where the blade goes into the guard, probably from sweat.

Good article here: https://knifesteelnerds.com/2021/10...ness-edge-retention-and-corrosion-resistance/
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I've read that article a few times now and I feel like my brain grabs hold of certain sections each time. I like the part about edge angle for intended use since I have a current passion for thin edges that I'm trying to see if they chip out or not.

To the point though, it did mention a rough finish is more prone to rust. I've never taken an edge beyond 1000 grit besides the cursory stropping just to do a final clean up from sharpening. And more lately I only go to 600 grit and the strop. This is a definite maybe kind of guess but I wonder how toothy an edge has to be to be coarse enough to be more prone to rust. Food for thought.
 
SharpBits said:
K390 is great, but I have not used it outside of the house yet. That's a steel I am concerned about corrosion. How has it help up in GA?
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Patina city but no rust. I even bought an aftermarket deep carry clip to easier carry it more often. I've hit two of those disgusting copper plated steel staples opening boxes and both times it left a tiny flat spot on the edge that a ceramic rod has been able to correct with a few swipes back and forth. Besides that it's been stropped back to paper slicing sharp on the same old black compound leather strop as everything else to keep that still mostly factory edge. As in I have yet to need to sharpen it. If anything in my EDC is the most carried it's the K390 Delica but I confess the E in EDC is really just M for most often carried. I hang my head low to admit it's not in the pocket today only because I recently ordered a custom Mini Grip with an M4 blade since that was sort of a bucket list mark off that I've wanted for years now.

TLDR, no rust, only patina.
 
SharpBits said:
K390 is great, but I have not used it outside of the house yet. That's a steel I am concerned about corrosion. How has it help up in GA?
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I don't live in a very rusty area, NW MT, as it is usually dry or cold. Spyderco K390 with pocket carry shows much more corrosion than Spyderco PD#1.

I have already used a surface conditioning belt to clean the corrosion off of the K390 knife when it for to ugly for me.


 
Seedy Lot said:
I don't live in a very rusty area, NW MT, as it is usually dry or cold. Spyderco K390 with pocket carry shows much more corrosion than Spyderco PD#1.

I have already used a surface conditioning belt to clean the corrosion off of the K390 knife when it for to ugly for me.


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That's my concern, right there. I guess I'll coat it with EDCi and hope for the best.
 
I don’t know what your particular leather slips are made of but I have had some that caused rust or corrosion and others didn’t. It could be a combination of salt, acidity or some type of chemical reaction.

The thing is leather can absorb and take on elements that it is exposed to not to mention the tanning process that was used to make it. And clothing can also be the culprit as well as what the blade was exposed to.

Also , Just a wipe down doesn’t always remove all residue and sometimes requires a rinse with fresh water and then drying. Some chemicals can be stubborn to remove completely and can still cause problems.

The only problem I have had with rust or corrosion is with a carbon back spring in contact with a 420 stainless blade with brass liners. I had thoroughly cleaned with soap and water right after use, rinsed and dried and then oiled it before storing it away in a drawer no sheath but a few weeks later it had rust between the blade and back spring and brass liners. I couldn’t figure that one out. It was a cheap imperial brand that I used as a bait knife so no big loss but it still surprised me. Ya never know!
 
Lesknife said:
rust between the blade and back spring and brass liners
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Guessing in the dark but I'd bet on water trapped between the two. I had similar issues in the 90's with a Gerber multitool that despite using compressed air to blow it dry I had to resort to spraying it with WD40 to really get the water out. Which then had to get more air to get rid of the excess oil.
 
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