I just bought a zinc/cadmium blackening sample kit from these folks and will come back and let everyone know how well it works. I have a pile of AFB idle mixture screws and accelerator pump "S" links which are plated clear (silver) cad that I need to blacken. We will see if this stuff works.
https://www.epi.com/black-oxide/cadm...ta-blak-z-360/