Hi Jamie - you caught me, it's Ariel! I started noticing the change a couple of weeks ago on some of the mounts I did right when we started antiquing. We just replaced the solution (there was also residue - brass and probably from the scrubber sponger we have been using to dull the patina) so I'm hoping that will help. The color has turned that silvery-dark purple in blotches, especially on the darker mounts. Which makes me think that the antiquing is continuing to affect the brass mounts after it has been rinsed.

The baking soda was on the label of the antique solution. We called the manufacturer and they had no "recipe" for mixing it so we just guessed. I'll look into it and see if I can figure out the specific manufacturer. I'll also look through Birchwood Technologies and the other companies you mention... thanks for the resources. Thanks for answering my post!