CPM S45VN staining?

S

stillshot2

Joined
Jun 6, 2014
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So I noticed on a satin finished CPM S45VN blade every time I would use it to cut food, say a tomato or cucumber etc afterwards where it passed through the food the steel would be slightly discolored in that area, even after washing. If I oiled the whole blade and kinda rubbed the oil into it with a cloth the blade would be uniformly colored again, almost like I was removing a patina that was forming almost instantly. Is this a thing with S45VN? Would a satin finished S30VN do this too? Because my satin finished SPY27 and VG10 blades don't exhibit this.
 
stillshot2 said:
So I noticed on a satin finished CPM S45VN blade every time I would use it to cut food, say a tomato or cucumber etc afterwards where it passed through the food the steel would be slightly discolored in that area, even after washing. If I oiled the whole blade and kinda rubbed the oil into it with a cloth the blade would be uniformly colored again, almost like I was removing a patina that was forming almost instantly. Is this a thing with S45VN? Would a satin finished S30VN do this too? Because my satin finished SPY27 and VG10 blades don't exhibit this.
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“Stainless” is another word for “varying degree of stain resistance”. Hard for me to guess what will put up with acids better, but I noticed you said it didn’t rust.

To me, unless your blade is exhibiting red rust, you’re golden.
 
Weird. I have a PM2 in S45VN but never noticed any staining. I cut up food at restaurants for my kids from time to time but never had any problems. What knife was it that was doing it?
 
If staining does bother you, you basically have the following options to get rid of the patina:
Polishing
Steel wool
A rust or patina eraser
sandpaper
Sodium bicarbonate or baking soda
White vinegar
Steel wool
Simichrome Polish
Of course all with varying degrees of endresults, if it's a knife with a nice satin finish like yours I would try to remove it as gentle as possible.
Tuff cloth also helps to prevent staining but is most certainly not foodsafe
 
I’ve noticed the same with s45vn. it’s been a great steel overall so hitting it with flitz when cleaning it out is a small price to pay in my book.
 
You mean like this?
20230123_084856.jpg
20230123_084911.jpg

That's a light residue mark from whatever you're cutting that's juicy/oily. Sometimes it will persist even after washing wish detergent; it won't rust your blade and is normal.

The example above is M390 which is very stainless. This happens on S35VN, VG10, Elmax. Etc, so don't worry about it.
 
Barskeepers friend.

Just a bit on a cotton swab and you'll be good to go.
 
RugerNurse said:
What knife was it that was doing it
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A Spyderco PM2, but no other satin Spydercos in other steels I own do this
Dergyll said:
You mean like this?
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Yeah, like the second pic, how it looks in the center of the blade. Never had to use anything abrasive, just oiling it seemed to help. I didn't think it was problematic for the blade but the extra work to get the blade nice and uniformly clean was a little annoying, kind of like a DLC blade after a soapy clean turns lighter in color and also likes a good oiling to get looking nice and dark black again. Made me wonder if it was a property of S45VN being a little less stainless than say, S30VN?
 
shane45-1911 said:
S45VN is more stainless than S30VN - it has more chromium
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That's what I have read and thought, which is why I was baffled. I no longer own the knife, sold it for other reasons but was just reflecting on it the other day is all.
DavidABQ said:
I think this is an opportunity for the OP it get a new knife! Maybe a nice custom?
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Definitely don't need more knives my Spydercos of "lesser" steel are treating me well. And definitely not a custom haha I like to stay in the below $200 price range.
 
Just an update for those curious I did buy an S30V Military a couple weeks ago that does not exhibit this "staining" characteristic my S45VN PM2 had. I probably will never figure out why. I also didn't see much improvement of S45VN over S30V in other areas anyways, at least for my uses. S30V is a solid steel in my book and I can see why Spyderco had no issue using it on the Military 2 as well.
 
stillshot2 said:
Just an update for those curious I did buy an S30V Military a couple weeks ago that does not exhibit this "staining" characteristic my S45VN PM2 had. I probably will never figure out why. I also didn't see much improvement of S45VN over S30V in other areas anyways, at least for my uses. S30V is a solid steel in my book and I can see why Spyderco had no issue using it on the Military 2 as well.
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It is important to remember the steel is only one part of the knife. When you see staining on your knife that is the result of the selected steel, heat treatment, grinding and finishing, other materials in contact with the blade, etc. Plus of course whatever unique environment the knife experienced both before receiving and in its initial use. Reducing the situation to “I guess S45VN offers no improvement in corrosion resistance” is likely inaccurate.
 
Larrin said:
“I guess S45VN offers no improvement in corrosion resistance” is likely inaccurate.
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I didn't say that, I simply said my copy of S30V did not exhibit what my copy of S45VN did in terms of staining under the same usage, and that I can't explain why. And then simply concluded S30V is a solid steel for my uses.
Larrin said:
When you see staining on your knife that is the result of the selected steel, heat treatment, grinding and finishing, other materials in contact with the blade, etc.
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This did cross my mind, unfortunately I don't have the capability to test that to know for sure but it's good to know these are possible answers to my situation.
 
My imput is both late and superfluous but CPM-S45VN isn't stain proof. Not that stains even alter or hurt the knife at all.
I bought an emerson government Mule once, not CPM-S45VN but 154cm, it was covered in rust spots. Yes it was authentic. But given the right environment, it's possible. Good luck rusting LC200N however
 
stillshot2 said:
I didn't say that, I simply said my copy of S30V did not exhibit what my copy of S45VN did in terms of staining under the same usage, and that I can't explain why. And then simply concluded S30V is a solid steel for my uses.

This did cross my mind, unfortunately I don't have the capability to test that to know for sure but it's good to know these are possible answers to my situation.
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[Deleted]
 
You should look at a native indian trade knife
Pitted rusted, patina'd discolored and --- stained throughout. Point is, it takes a looong time for that stuff to literally break the knife
Don't worry guy
 
ShaiHulud said:
You should look at a native indian trade knife
Pitted rusted, patina'd discolored and --- stained throughout. Point is, it takes a looong time for that stuff to literally break the knife
Don't worry guy
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I was never worried about the integrity of the blade, I ended up selling it for different reasons but it was just weird to me it would get these spots despite me taking really good care of it where my other satin finish knives made of VG10, S30V, SPY27 were treated less special and didn't do this.
 
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