Gelcoat/'glassing question.

I'm getting ready to glass in a rear spoiler onto a fiberglass bumper for my '84. The spoiler is the familiar version that normally bolts on the early C4s, but I prefer a cleaner one piece look. The spoiler has a thick layer of gelcoat on it, and I'm curious about getting the stuff ground off and getting a good adhesion to the fiberglass underneath. I've 'glassed a bunch of bodywork over the years, but never had to work with something that had a bunch of gelcoat on it first (plus trying to repair big nicks in the gelcoat). Any advice or recommendations?

thanks,
Mike

Mike
I have always used 40 grit sand paper to scuff up the area that I need to bond to. I usually scuff the are real good and go about 1 inch out further than I know I need to just in case. The only concern that I would have with what you are doing is the force of the air on the spoiler causing stress on the bonded area. If at all possible I would try and reinforce the area on the inside side of the area. If it is impossible to get to the inside of the spoiler to bond it then I would look at using a bonding agent. There is a lot of good body panel bonding materials that will make it rock solid and the fiberglass work on the outside will be more cosmetic than structural.

Just my 2 cents!