I know this thread will most likely be deleted or closed, but Someone has to ask, and I did do a search. It's been a long time since I painted , but this is the first time I have tackled fiberglass. My ot car has a white gelcoat already, would that work well enough to paint over, or do I need to go ahead and prime it? I know I'll get hammered for asking a stupid question- What is the benefit of primer over gelcoat? Here's the car- a replica of a 1966 Don Edmunds supermodified..sort of.
For most fiberglass applications, you finish them the same as you would a steel surface. Sand, primer, etc
If you go to Wescotts site they have instructions on prepping a glass body for paint. It's just as 32 SEDAN said- sand, prime then paint. Here's the link. http://www.wescottsauto.com/WebCatalog/HowToPaint.pdf
"Primer" is a little too generic of a term. Specifically there are 2 basic types of primers. "Primer surfacers" are used to fill small imperfections and usually need to be sanded before the application of the next part of the refinish system. The primer surfacer fills sanding marks and is sanded with a progressively finer grit of sandpaper to smoothe the surface for finishing. "Primer sealers" are used to seal the surface to be painted. They provide extra adhesion or help "tie" the base finish or primer surfacer to the paint or topcoat and also provide a uniform base tone to help with paint coverage and hiding. Primer sealers are usually not sanded before applying the paint and are usually specifically designed for the topcoat paint system to be used. Application instructions will tell you the time "window" that a sealer can be sprayed over without sanding. If your gelcoat is rough or damaged, it should be cleaned and sanded then primed with a primer surfacer to fill imperfections, then resanded to smoothe out the finish and for adhesion of the next layer. If your gelcoat is in good shape, you could sand it and clean it, then use a primer sealer compatible with your paint system. overspray