Help with prepping for paint

Hello need advice working in these fiberglass motorcycle pieces to get them ready for paint, question I have is once repairs are done to fiberglass do I need to use a primer sealer or a primer filler or both I attached pictures of the part I’m repairing and preparing and what I’m trying to accomplish, any recommendations will be highly appreciated

Ok I’m no expert here but I have done a few bikes and I’m working on a fiberglass car. So here’s what I did. I recently did a 77 BMW R100RS motorcycle (there are a few pictures of it here on the PUB). Not sure if the faring is fiberglass but it is plastic. I basically handled it just like as if it was metal. I sanded the body work using 80, 180 and whatever until I got to 320 grit. Then primed it with 2K primer. Be sure you adequately cover the repaired parts with 2K to avoid color variations later. I used 2 coats of 2K, but you may need to apply more on the repaired parts to get even coverage (the body filler seems to absorb the primer more than the non repaired parts). Once primed, I wet sanded it with 400 grit, cleaned off any sanding residue, wiped down with tack rag, then applied BC/CC.

I pretty much followed the same procedure with the car I’m working on, with a few exceptions. The whole car is fiberglass and gel coated. I washed the car with cleanser and scotchbrite pads, filled any imperfections, sanded the entire care with 80 grit, then sprayed the entire car with Slick Sand (sprayable body filler), guide coated it when dry, block sanded with 220 grit, then sprayed 2 coates 2K primer,sanded with 400 grit, then BC/CC.

I have found that everyone does things a little different. So it you ask 50 people the same question, you’ll get 50 different answers. You need to figure what works best for you. This seems to work for me. Hope it helps.

Good luck
Paul (z3beemer)

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