What caused/causes this?

Fletch Helical

Fletch Helical

Joined
Sep 29, 2009
Messages
1,614
Quite a few years back I got a knife from a guy I knew who said someone gave him this knife. I never really used it but the other day I looked at it and noticed this blackish looking stain, almost like an oil stain in the blade. There is some on both sides of the blade. this was about the best picture I could get and it's the bigger of the two patches.

I have no idea what steel it is. All I remember is I saw it at his house and asked him where he got it. He said someone made it and gave it to him then he asked me if I wanted it so I said sure.

PA290546.jpg
 
looks like something dried there, like blood. I guess it is an acidic liquid not wiped for hours and formed a patina...
Emre
 
I washed it with a soap and sponge to try and get it off. It never even smudged and it's randomly on hte blase, both sides. It almost looks as if it's in the metal itself.
 
I would guess that it is a non stainless that has encountered blood or other liquid that has etched into the blade.

George
 
I'm thinking the same,some type of carbon steel stained by an acidic.
Stan
 
Not just stained it looks well etched into the blade. Looks like it ate up a thousandth or so of an inch.
 
The majority of the blade will have to be sanded down to level with the etch. It can be done, but you can't just sand it away.
 
If you want to try and see what depth the problem is, use some Simichrome or Flitz polish on it. If it comes off, or is greatly removed,No problem. If it gets a lot better, but still shows a bit, it will be no problem to lightly sand the blade with 400 grit and clean the rest up.
Stacy
 
It looks like a coffee stain to me.

What Stacy said, try polish first, then sand if the polish doesn't work.
 
Unless I try something like Flitz from what I can see the stain isn't easily coming off. From what I was told someone made this knife and gave it to the guy. It's in a handmade looking sheath and doesn't appear to be a factory knife. So I was wondering if it was something that could have happened during any of the heat treating process??
 
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