How do I get a blue patina on a stainless steel blade?

C

Carmasaurus

Joined
May 28, 2014
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Hey everyone!

This is my first post here and forgive me for asking questions right off the bat but was wondering if anyone knew what to use to give a stainless steel blade a blue patina. I would really like it to have a "case harden" type look but would be cool with it just being variations of blue. The steel is 7cr13. It is a united cutlery kerambit.

I read on here that people have accidentally put a blue patina on a knife by cutting apples or onions while others used mustard, ketchup, mayo and bbq sauce. Is there any where that lists the different effects from different applicants?

Any info on this subject or sources would be helpful! Thanks a lot.
 
It's almost impossible to get stainless to darken. If it has a high enough carbon content you might get a little. Try cutting up some lemons or pineapple and let the juice set for a little bit. There are ways to blacken stainless though - look at Brownells website. They have the chemicals. They're not cheap. I wouldn't bother to do it. Find a nice 1095 carbon steel knife. That's all I use in the kitchen and most of my carry knives as well. They all have a really nice patina and can slice through a tomato like a laser. Once you go 1095 it's hard to go back to stainless.
 
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Well the knife is going to be more for show. I am trying to emulate a design from CS:GO. Something similar to this, http://3.ii.gl/25ZM7N.png. I wish the knife was better quality steel but I could only find this style with the 7cr13.
 
Good luck on getting stainless to patina it probably won't happen, those blades you hear people putting a patina on are carbon steel blades. You probably have better luck getting artistic on that knife with some type of paint than to find out what to use to get a stainless steel to take that specific type of patina. In fact I think you have better luck hitting it big in vegas than getting that type of patina on that knife.
 
Tried it, unsuccessfully.
Tried boiled Balsamic vinegar and then lemon juice. Did not take on a VG10 blade.
Needs to be high carbon steel.
 
Sosa said:
It looks like heat was applied to the blade to create that effect.
Click to expand...

Yep, you'll have better luck doing that with a blowtorch than with chemicals. And if it's not a carry knife, you won't have to worry about damaging the temper of the metal.
 
ya that looks like a heat induced patina. if you carefully use a blowtorch to heat up the steel you can get coloration similar to that. it will totally scew up the heat treat on the blade but its just a thought. also if you screw it up you can always sand or blade down and try again until it turns out right.
 
another way to go about it would be some type of electro-plating. I would recommend looking around at the replicapropforum and see if anyone has done any steel coloring that way. One of the big flaws with heat coloring stainless, in my experience is that because you are changing the chemical composition of the very surface, it will discolor and rust very quickly. It might not happen with that particular steel, but I've never found heat coloring to be stable on steel. Titanium is, but thats because titanium stabilizes and seals itself as it oxidizes. There are also coatings like marking fluid and such that can give you a anodized look, but any chemical coating will likely not be food safe. Not a big deal for a prop knife, but those chemicals are not fun.

Another idea would be, if you want to try doing a prop knife, start from scratch, or get a really cheap bit of chinese steel instead of heat killing a blade you spent money on.
 
If it's truly just for show duplicolor metal cast is an option. You can paint fog lights, mirrors, chrome and whatnot. It's a fake anodized like finish.
 
Battery acid (sulfuric) with darken stainless. I tried it on an old 440c buck 112 blade. It won't turn blue but a nice grayish color
 
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