I'm not sure what to advise, as the times I did body paint for Amethyst I was able to use eye shadow for eyes and contouring just fine and I was also using a water-activated paint. I didn't use a primer and only sealed after all my makeup was done. Maybe it's just drying too fast, have you tried just using a little more water for more blend time?
Or I guess if you're wanting to put it on "over" the body paint once that dries, it could be an issue of it not sticking to a non-skin surface. I'd imagine the body paint isn't as porous as actual skin (though certainly more porous than regular paint) so maybe the sealing suggestion would help.
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