I just tried to tint two canopies. One was from a World Models ARF and the other just a no-name Chinese mfg's "discount" ARF.

Neither of them took a bit of color from 2 packs of black, 1 pack of Navy Blue, vinegar, and salt. I let them sit in the brew in a pot that was sitting over a fan housing that shakes, sort of a poor man's "ultrasonic" bath. They jiggled away for about 3 hours. I'd washed them off with soap before trying to die them just in case there was some kind of mold release or whatever on them.

After they failed to take the die, I washed them again and decided to spray paint them with Testor's canopy tint. It's lacquer I think. It usually works halfway decent. It went crazy with spots. I'm guessing that the salt or maybe the vinegar had actually gotten into the plastic and was brought out by the thinner in the lacquer.

So I blew time and money on the die, and that wound up screwing up the painting.

Some things work, some things don't. And some things don't work and screw you up even more.