Being in the business of fiberglass molding. I will tell you what I recomend and the reasons why.

1. It is correct to wash the model with water and a detergent. There is a reason why. The mold release, if PVA was used, is only water soluable. Nothing else will remove it. Wash with warm soapy water and the rinse several times. Then use a quality tac cloth to clean up with. When you sand the model, any residue from the soap will be removed.

2. I suggest using 3M 600 grit paper WET and LIGHTLY sand all the surface. Anything heavier grit than that will remove any details , and leave sanding marks. I cant stress enough, lightly sand. If you press hard or stay in one area longer than others, you stand the chance also of sanding through the finish coat of resien and into the fiberglass itself. Then you have a mess on your hands.

I would also use a really good quality primer sprayed lightly before paint. As would many professional paint people would agree, Use the same brand of paint from primer to finish coat. Then you have NO issues with compatability.

My two cents. And good luck with it

WBG