I’ve used Dupli-Color Filler Primer – Grey 26916 32101 a number of times and it works great. I use the grey just as a filler and then put down the required LusterKote primer as the final prime coats before the color coats. The base under the primer was polyester fiberglass resin and cloth. The required LusterKote primer doesn’t work very well as a primer so that why I start with the Dupli-Color. Without the white LusterKote primer the colors will not be correct.