Be sure to spray any filler you’ve added at this point with a coat of primer. Body filler and metal glaze are porous, and if you just paint over it, it will suck the paint in, leaving shallow but perceptible craters in your glossy topcoat. If there are only a few areas of filler, you can coat them with an aerosol primer. After blocking the El Camino and filling the remaining low spots, we sprayed the entire car with another coat of Eastwood’s urethane primer. Priming the car one more time prior to topcoating it is also a good idea because the car is all one color prior to painting. Sometimes, a patchwork of primers can show through paint as slight shadows or light spots. That’s the last thing you want after all this work.