So, it turns out you can patina brass fairly easily. I basically experimented as I am getting terribly bored with the cheap brass hardware that you get with most production katana. The thing is, Im pretty sure its because they can cast the habaki whereas with copper its more complex. Nonetheless, this is how to do it.
Take a container and put vinegar in the bottom. probably about an inch. you need space at the top to suspend your objects so bear that in mind when selecting a container. Put that in a warm place.
Next you need to polish the brass you want to patina. you cannot touch the brass after the polish as the residue from your fingers will inhibit the corrosive action of the etchant. Yes, once again, what we're basically doing is etching. However this time we wont be soaking the brass in the etchant, we will be hanging it above the liquid, and the fumes will be forcing the patina.
When I say polish, also... I mean like a mirror. Not a satin polish, not a quick wipe. Nope its time to break out the 2000 grit wet n dry and be meticulous. If youve done it right, it should look something like this.
This means that the surface is even and as such, the patina will also be even.
Once you have done this, you suspend the items above the vinega. I used 1mm copper wire doubled over. I just stuck two holes in the lid of the jar I was using, and hug them like that.
Once youve done this, you simply leave it in a warm place. I put it on the windowsill as the weather here in the UK has been pretty hot recently. Bad for me because I melt, good for patina's. So its a trade off I'm ok with.
Sometimes you will see a green residue on the brass. simply wipe it off, gently as you can and replace the items. continue with this tedium until your desired colour is reached. This is what they looked like afterwards. I think it took about 2-3 days.
They actually turned out darker than this but my camera was rubbish and so I have included below a shot of the sword they ended up on which more accurately depicts the colour.
So, thats all there is to it. you need a bit of patience and you wont be able to use your sword for a few days (obviously) Good luck and remember, preperation is everything. polish until you can see your face in it :)
Take care peeps and have the most excellent day.
\m/
so helpful. this knowledge does not go unrecognized!