Well this is how they turned out. These are some Herder carbon blades that I changed and am going to try to make a match pair with a double sheath for. I used some spicey brown mustard first and it did a beautiful purple-blue design but when I put some oil on the blade it went away?   :confused:  This was done with lemon juice and turned out pretty neat looking. Unfortunately the pics aren't that good.

Did you use any heat?  Let them soak?  Whats the process?

I just let them soak with a paper towel around them. I guess that made the patterns on them? About 30 minutes I think.

Skullworks I'm really interested in this process . I finished my first knife a while back and gave it a soak in brown vinigar overnight , it came out an even light grey - I really like the patterned finish , I will try lemon juice on the blade I 'm working on now . regards Jacko

I think the paper towel is what created the pattern. Where it touched the blade and didn't. It is hard to tell but the blades have a kind of brown patina in the lighter areas.