Southern Polyurethanes (SPI) Plastic Adhesion Promoter is used on bare plastic to increase the adhesion of various layers of paint sprayed on top of it.  The rule of thumb for using SPI Plastic Adhesion Promoter is “If it floats- Promote!” cut a sliver off the backside of the bumper or plastic, if it floats in the Adhesion Promoter then use Adhesion Promoter.  It comes ready to spray and only prep surface with waterborne wax and grease remover and not solvent based.  It is ready to coat after 30 minutes, but no longer than an hour.  Coat with epoxy or 2K primer before paint.  Available in quarts only.