Acid etch and cold blue together?

N.N

N.N

Well-Known Member
question: What happens if you do a ferric chloride etch and then cold blue?

I'm asking this because at the last minute, I've decided that I'm not going to handle a knife. I'm going to leave it plain steel. It's 1084. Only the blade has been heat treated. I know that if I want to blacken this blade as much as possible, the ferric etch will work well. However the handle, which is not hardened will be a little lighter in color. What would happen if I soak this in ferric for a while, clean it up, give it a baking soda bath for a while to help the etch stick and then cold blue it?

Will the cold blue do something funky or darken it more?
 
I've used cold blue and then a bleach bath to do etching. I always finish with a round of cold blue and then 0000 steel wool. Leaves a dark gray finish with darker gray to black in the pitting.
 
I don't want the pitting though. I'm really wanting something to just make it blacker where it's not hardened.
 
If you're working on differentially heat treated blades, etc., there will always be a major color difference between hard, and non-hard areas, no matter what chemicals/solutions you use......its just the nature of the beast.
 
Against my better judgment, I went ahead and acid etched this one for 20 mintues to get it really black. After a boil in some baking soda, the blade was as black as night, but the handle was only gray. I then coated it is some super blue and it left it much better off. It worked pretty well I think. It's not streaky like cold blue can do and it's a very matte black opposed to glossy. I'm ok with it I think. The only part that's a little off is the heat treat line.

20150718_130637 copy.jpg
 
I've had that problem before too and I don't think there's much you can do about it. It seems to me the more you etch or abrasive blast it, the more it shows up. I've sort of hidden it with hand sanding up to a pretty fine grit, but you can still tell. But hey, just do what I do. Tell them what it is and how much time you put into differential hardening, how much better the knife is because of it, compare it Japanese swords and high end Bowies. Make it sound like a special feature, not a flaw. :biggrin:
 
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