Why is my blade discolored? w/pics

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Aug 10, 2013
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I stripped the coating off of my Ontario RBS 9 and noticed several dark, discolored areas on the blade. Is this a result of bad heat treatment? Will the dark areas be weak spots in the blade? I have used this stripped before on several knives and have never had this result.

Thanks

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I seem to remember reading that Ontario differentially heat treat their blades, if so that combined with the type of steel used could explain the color difference in the steel. But I could be completely wrong :confused:
 
I seem to remember reading that Ontario differentially heat treat their blades, if so that combined with the type of steel used could explain the color difference in the steel. But I could be completely wrong :confused:

If that blade was differentially heat treated, it wasn't on purpose. :D
 
Patina?

Oils from skin can do that if carbon is high.

Yep. The knife in question is 1095, so it probably got a patina while waiting to be coated at the factory. Doesn't make much sense to polish them before coating, so I suppose it just got left on underneath.

Either that or it just oxidized during the stripping process and noneof the OP's other knives are carbon steel so he's not noticed this before.

Either way it definitely looks like a patina to me.
 
Well, you never know--in spite of being owned by an aeronautics conglomerate, Ontario isn't known for having the most consistent heat treatment, so you may be right! Like I said, though, if it's happening it's not on purpose. :D
 
I've used this same stripping process on several 1095 Beckers and never noticed the discolorations. I put a heavy patina on the blade after stripping and now you can't see where the dark spots were, so it must have patina'd at the factory awaiting to be coated.....or it's going to break in half when I chop with it.
 
There looks like a chip in the blade in the first picture.......but that's just me probably.
 
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