Please help..Is this rust, or what is it??

joeyza

joeyza

Joined
Feb 27, 2013
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Took part my strider smf after a couple of months to clean it and noticed this slight discoloration on the very back of the blade. Any ideas to what it is and what may have caused it. COuld it be rust? Have kept it very well oiled so have no idea how this happened.

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Looks more like heat discoloration, odd that it would be on the blade after stonewashing however. Might have been from grinding the locking interface after finishing?
 
Doesn't look like rust to me.....but I can't be sure. It would be very odd to get rust under moving parts and not anywhere else. When I get rust on my knives it it usually near the pivot but never under the washers.
 
yoda4561 said:
Looks more like heat discoloration, odd that it would be on the blade after stonewashing however. Might have been from grinding the locking interface after finishing?
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that was I was told by someone else as well but I have taken this knife apart many times before and this is first time I've seen it which is why i found it odd. I also dont think its rust but couldn't think of what else it might be...
 
yoda4561 said:
Looks more like heat discoloration, odd that it would be on the blade after stonewashing however. Might have been from grinding the locking interface after finishing?
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The way it radiates from the lock-tang makes me think the same thing. I've seen it before, but I can't remember if it was on my own SnG or in pictures.

Now, whether that is a problem or not... I don't know.

P.S. - Nice pictures. :)
 
Doesn't look like rust at all. Have you tried metal polish to remove?
 
You should be able to ding MAAS or maybe even flitz at a hardware type store.
 
Just a thought. Does that knife use bronze washers/bearings in the pivot? Just wondering if that discoloration might be some of that (bronze) wearing off and/or embedding in the steel. Color looks about right for that. Doesn't quite look like rust, to me.


David
 
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Obsessed with Edges said:
Just a thought. Does that knife use bronze washers/bearings in the pivot? Just wondering if that discoloration might be some of that wearing off and/or embedding in the steel.


David
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Yes it does use bronze washers. Hmm didn't think of that! can bronze washers wear away and discolor a much harder steel like s30v tho?
 
joeyza said:
Yes it does use bronze washers. Hmm didn't think of that! can bronze washers wear away and discolor a much harder steel like s30v tho?
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If the washers are doing this, it would be the bronze being worn away, and it's resultant bronze 'dust' getting embedded in the surface of the steel. The washers wouldn't wear the steel away; it's much too hard & abrasion-resistant. The washers should wear, and not the steel; it would be self-defeating the other way around. I think part of the 'self-lubricating' nature of bronze washers is due to some of it's material being able to slough off this way.


David
 
I wouldn't even worry about sanding it off. That could make new problems.

Oh, by the way, how does the other side look?
If it was heat discoloration, I would expect it on both sides.

Obsessed with edges makes an interesting theory. The G10, where the washer wears, has a bronze colored circle now on my SnG.
 
Obsessed with Edges said:
If the washers are doing this, it would be the bronze being worn away, and it's resultant bronze 'dust' getting embedded in the surface of the steel. The washers wouldn't wear the steel away; it's much too hard & abrasion-resistant. The washers should wear, and not the steel; it would be self-defeating the other way around. I think part of the 'self-lubricating' nature of bronze washers is due to some of it's material being able to slough off this way.


David
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Is that true? Every knife I disassemble has a polished spot on the tang from wear against the washers. Perhaps it is not removing steel but burnishing it?

Can't a softer material wear on a harder material? How do you explain wear on a door knob from the soft skin of the hand?
 
Nullity said:
I wouldn't even worry about sanding it off. That could make new problems.

Oh, by the way, how does the other side look?
If it was heat discoloration, I would expect it on both sides.

Obsessed with edges makes an interesting theory. The G10, where the washer wears, has a bronze colored circle now on my SnG.
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The other side also has the same discoloration, just not as prominent. But if it was heat discoloration it should have been there from the beginning right? This is the first time I've seen this and I have taken it apart many times before.
 
Nullity said:
Is that true? Every knife I disassemble has a polished spot on the tang from wear against the washers. Perhaps it is not removing steel but burnishing it?

Can't a softer material wear on a harder material? How do you explain wear on a door knob from the soft skin of the hand?
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I'm sure there will be some polishing/burnishing of the steel, to a point (doing some online reading that suggests this happens as part of the 'break-in' of the pivot's function). But if the bronze were actually hard enough (or abrasive enough) to continually wear the steel away, that would defeat the purpose of putting the washers in there in the first place, I would think.

At any rate, I don't think your steel is being harmed, assuming it's only bronze that's discoloring it. May need re-thinking as to what lube to use, so as to minimize how much the bronze washers are wearing away.


David
 
Nullity said:
Is that true? Every knife I disassemble has a polished spot on the tang from wear against the washers. Perhaps it is not removing steel but burnishing it?

Can't a softer material wear on a harder material? How do you explain wear on a door knob from the soft skin of the hand?
Click to expand...


You are correct, softer materials will wear on harder materials. Some people dumb it down way too much when they think that a hard surface cant be damaged by a softer one. Its simply not true. It simply requires more force (velocity) and/or more frequency. A perfect example are the blades on the very knives we use every day. I know nearly every single one of my users has scratches in the blade. Yet I dont go around cutting anything remotely as hard as the blade itself. There is a whole lot more going on when considering if one material will damage another besides hardness. The most basic I can think of that everyone will understand is a lead bullet. Thats a very soft and malleable metal. Yet when enough force is applied to it will penetrate steel.
 
joeyza said:
The other side also has the same discoloration, just not as prominent. But if it was heat discoloration it should have been there from the beginning right? This is the first time I've seen this and I have taken it apart many times before.
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That most certainly looks like the steel was getting a little hot when grinding the face of the lock. Sometimes these colors wont be as noticeable and then after using a cleaning solution like windex and removing oils it will be more apparent. You can even see where the washers riding on the face of the blade have started to remove the coloration. I would be willing to bet you just didnt notice it. Judging by the color its nothing to worry about. There is no burnt colors or blue/purple notes. Once you start getting to that color the hardness can be compromised.
 
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