I'm in the process of stripping and repainting my spoiler. Someone painted it black without sanding or using primer and the paint has bubbled up and fallen off in areas. I bought a fiberglass-safe stripper from Eastwood. It worked well but left spots of original black paint that you can feel when you run your hand across it. The other exposed areas are white (I'm assuming this is the gel coat). I tried re-applying the stripper, but the spots won't come up completely. I could sand it, but I don't want to go through the gel coat. It my only option to apply enough high build primer to be able to sand it smooth, then paint?