I saw your question on Ganoksin & I think I have a solution for you.
I’ve been using a lot of brass lately, due to the high cost of gold,
and I had the same problem.
After torching my brass piece, I place it in warm pickle first,
which brings copper to the surface (the pink coating you mentioned).
However, I then put it over into a mixture of warm pickle & hydrogen
peroxide for about 10 minutes (1-to-1 mixture, or 2 parts pickle to 1
part hydrogen peroxide- I’ve done it successfully both ways). The
result is a beautiful matte gold finish, which I love.
You might be able to skip the step of placing it in plain pickle
first - I’ve just always done it that way, but I’m going to skip that
step on my next piece to see if it still works as well. And I’ve been
told that the pickle/peroxide mixture doesn’t have to be warm
(although the warmth will supposedly speed up the process).
I keep a separate pickle pot that I use exclusively for this
purpose. From this special pot, I pull out however much warm pickle I
need, mix it with the peroxide in a plastic cup, & add my brass
piece. When I’m done with the mixture, I remove my brass piece & pour
the liquid mixture back into that same special pot with the original
pickle inside. Bear in mind that this process continually dilutes the
pickle with more & more peroxide. At some point, I’m sure this
mixture will be mostly peroxide & may no longer be as effective. I’ve
done this about 8 times so far and it still works very well with my
diluted solution, so I’m going to keep going with it until it quits
cleaning my brass, and then I’ll dump it, make a fresh pot, and
I hope this helps!