Brass, red brass, newgold- all of them are going to copper flash (pickle plate)
in the sparex pickle whether it has been contaminated with steel tongs or not.
But you can mix an anti-flash pickle by adding hydrogen peroxide to the sparex.
You need basically a 1 to 1 mix of your sparex solution to hydrogen
peroxide. (a test is good to make sure it isn't so strong it pits the metal)
This solution will eat the copper off brass that has been flashed- so your
students will be really happy they don't have to sand copper off anymore. It
works really fast when it's hot. It doesn't keep indefinitely like sparex.
The life of the solution is probably not more than a day, so I wait until I am
done with all the heating steps on a brass piece and use the anti-flash only
once at the end.
Visual Art Studies
University of Texas at Austin