i dont think that you fiberglass to your car. you use fiberglass to patch something that is already fiberglass. my friend mack told me that and he works in a body shop. i actually just refiberglassed the wing on my monte. but hey. go get an expert opinion. im only going on what i was told.
You should never apply just fiberglass to a car unless your using it to patch a spot. In that case sand down the area with anything from 36-120 grit and apply. If your planning to mold a bumper or shave your trim with glass also remember to make sure all the peices your glassing are secure. Ive seen it to many times where someone will mold on a bumper and the bumper wont be secure and the glass will crack in a matter of days. So what exactly are you going to fiberglass?
fiber glass doesnt like to stick to metal... if you patching a hole, spray expanding foam in the hole, let dry, cut off excess, then fiber glass over the foam, since fiber glass will just keep making a hole and falling in with out any support behind it... thats after sanding and all that tho.
