Ok Im sorting some new test pieces out tomorrow and Ill try ferrobronze on it.
Out of interest have you or anyone else tried Aa 22 Black brown solution. Angier rates it quite highly in his book and the ingredients are pretty easy to get. Maybe worth a try as well.
And one last thing, when I put the test piece in the boiling water it drops the temperature below the boiling point for about 15-20 seconds. It then climbs back and converts the rust, but would that initial drop in temperatures cause any detrimental effect on the metal colour? Just a thought.
JMH
