Most of the color shift pigments I have and use had use suggestions on the website's selection. Many indicated that the pigment could be mixed into black paint/fingernail polish as well as applying it over black. I have mixed some that had the suggestion of being used in black paint into black plastic with some success but I needed more pigment to be put in the plastic and just wasn't willing to use any more to get a better result. It would take a lot of pigment in black plastic. I use white particle color shifts in clear plastic to be used as a cover dip over black and that works super.
