I received the rear callipers back from the zinc coaters, but the coating has not taken on all the metal, it looks very poor. I have had no option but to send them for powder coating to at least get them consistent.

I think I delayed them getting plated too long after they were cleaned at the sand blasters. Somehow the metal became contaminated either from adsorbed brake fluid or some other contaminent. Never mind they will still work and can’t be seen anyway! So I have gone for zinc yellow!