DP, what ratio did you use with brown solution and aqua-fortis.I would like to have a rust blued barrel on my current project and happen to have a little aqua-fortis left from previous build.Thanks
About 50-50.
I just dumped in some, tried it and it worked.
People should note that rust bluing is not the same as browning. Boiling the part and converting the red oxide to black oxide produces a very different surface than simple rusting. The surface is harder and more rust resistant than the red oxide and once well established it does not rust well without some nitric in the mix.
The nitric also produces better color IMO.
The barrel must be tightly plugged with wood plugs and the bore kept oiled. Plugs are removed after each boiling, the bore wiped and dry plugs installed. I card with *degreased* 0000 steel wool.
I got the idea for adding the nitric from a formula in Angier's book "Firearms Bluing and Browning".
Dan