7000 series parts dye, but 6000 series won't

[acidrain]

Thanks for the input guys...
I just did a couple paintball guns, and they are dying a much deeper color now. So far, no acid "carry-over" streaks either!
My method for rinsing is:
Spray rinse into the ano tank paying special attention to the small screw holes, etc.
Dunk in distilled water until ready to dye.
Spray rinse again coming out of the dunk tank, and going into the dye tank.