Spider marks on carbon blades

[Hammerhead]

What is it that causes those black squiggly (spiders) marks on knife blades?
Don't think I have seen them on stainless before.
Is it some sort of fungus or bacteria colony that excrets an acidic waste actually etching the material? (just a guess)
A fungus does similar damage on camera lenses stored under humid conditions. The bacteria in our mouths excrete an acicic waste causing cavities over time.
I can't get my mind around oxidation causing such deeply etched localized tracings.
What can be done to prevent them or stop their progress?

[jabberwocky]

Hammerhead...

I read an article some time ago (sorry...can't remember which knife book/magazine) that talked about something similar...I'd had it happen on a knifeblade or two. Anyway, I remember reading something about a condition called carbide precipitation...something to do with heat treatment that can cause "intergranular corrosion"...even on stainless steel. I don't know if this helps at all...but it may lead you to find something on this problem if you look/research in that direction.

cj

[El Lobo]

You know, my wife says I've got that "Intercranial Corrosion" thing...thanks for pointing that out.

Joking aside ,

http://www.corrosion-doctors.org/Forms/ ... anular.htm

Bill

[Hammerhead]

Thanks for help Jabber and El Lobo

So far looking for the terms you suggested leads me to nothing that resembles the the patterns on my knife or ones I have seen.

If you click on the picture and supersize it you can see them pretty well. (took me a few tries to get a good photo)

Just curious about what causes it and preventative measures for it.

[El Lobo]

Yeah, we know the marks, they are a big bummer.

I've heard...spiders, spider webbing, ribbons, peppering...maybe other names.

Here is a "Corrosion Glossary".....

http://www.corrosionsource.com/handbook/glossary/

.....of course, none of those are listed.

But, the description might be in there somewhere. I went through a few guesses...but, no joy for me.

Bill

[jabberwocky]

Hammerhead...

Now you've got me curious! Do the affected areas actually appear to be
corroded? Rough to the touch? Or are they more like small stains "within"
the metal itself.

On the knife I had a while back which had similar marks, they seemed to be almost like a stain within the metal of the blade...you couldn't feel them if you ran your finger over the spot.

Maybe one of the other guys on here could tell you how to deal with them, if they could be rubbed or buffed out, etc. Sorry I wasn't more help.

[Hammerhead]

Looking at them very closely with a loop they are deep squiggly shaped pits, or lines radiating from a centralized area where they probably started from.
I couldn't say just how deep they are but that they can't be removed by any means other than removing some steel with them.
This Muskrats' example marks it for life in my opinion and I wonder if it will continue to get worse.

[jabberwocky]

Hammerhead...

I did come across this info on another forum...


go to:

http://www.bladeforums.com/forums/archi ... 10695.html

[El Lobo]

Here is one (on the tang) on a knife I have. No polish or such has any effect, unfortunately. But it has never changed in the 5 years that I've owned this knife.

Bill

P.S.
Sorry about the pic...the squiggly looks like a cobra there on the tang.

[Hammerhead]

I been doing a lot of hunting for this and the only thing I can find is this.
http://www.chem.fsu.edu/steinbock/projects/ffc/ffc.htm

Further research into this name of corrosion leads to it on aluminum more than anything.