it also sounds like the solution may have been too strong. Did you
use regular "drugstore" hydrogen peroxide? (NOT the beauty-salon
strength?) I've used that cut 50/50 with pickle and left pieces in
for almost as long as you've cited, without any etching in
sterling, which is why I suspect that.
I used regular 3% peroxide (i'm a brunette, after all), but heated
it and added a few teaspoons of very concentrated fresh pickle. I
think you're right, though - the mix was just too strong. It seems I
can buy citric acid crystals online for about $3/lb so I'll do that
as soon as I use up my sparex.
BTW, I think the pink tint was more due to overheating than plating
because it occurred unevenly - primarily on the gold that had been
through the most soldering operations.
Thanks folks for your tips on- and off-line.