Mineral spirits and a comb works. For paint & finish waste, I mix it with wood shavings and let it dry, then bag it for the trash. Our local landfill will accept most any type of finish as long as it has cured.
"Grund" -dispersion primer
"In contrast to conventional paints, the feel and appearance continue to be reminiscent of a raw, finely ground wood. The best result is achieved with a previous primer by Bona White. Enjoy the feeling of natural wood."