Thread: Forced patina on carbon steel

I used yellow mustard on my Gotta 120. The blade was all scratched up so I decided to polish it out and darken it. After a few tries on a test razor, I really like how it came out. I kept rubbing the mustard onto the blade with my fingers for about 5 min, rinsed in hot water then dried it off.

Originally Posted by RezDog

Mike Blue put that one to bed. As there are very few people with his level of experience and knowledge of blades and metallurgy, I'm pretty happy to believe anything he says on the issue.

All I know is that some people experience problems with different staining chemicals. But they all seem to disappear after the first sharpening.
My own theory is that the carbon steels actually rust at the very edge and the first use after the staining removes that rust and now its not that sharp anymore. I have also read reports of brittleness at the edge (can't remember forum (but it was a kitchen knife forum I think) or steel or chemical but the steel became chippy until a new 1k bevel was put on there, and then the regular progression iirc).

Sure some chemicals are more aggressive than others. What I've picked up from the kitchen forums is that mustard, blood, onions makes nice colors. nicest patina I've ever seen was made by splashing blood and then mustard on the blade iirc, turned out light brown and blue/purple (probably only visible in some specific angle and in some specific light situation, I'm guessning the colors are a result of destructive/constructive interference, like anodizing Ti), but it was cool looking.

Onions seems to be a favorite since after a few passes through an onion (and left soaking for 5 mins) the blade seems to "passivate" (but this is probably not completely true). It is what it is.