Fiberglass resin surface preparation 85 300D: Must metal be bare or can it be primed?
 

I'm preparing to use epoxy resin & fiberglass cloth in a few areas on my 85 300D, for additional strength and not for primary metal replacement.

One such area is the lower front cowl which always cracks at the seams and starts to corrode. Can I apply fiberglass resin with a Good Strong Bond over a primed surface or a surface treated with something like Permatex Rust Convertor, or can I only apply it only on wirebrushed bare steel?

I know you can't put it on galvanized steel without grinding away the galvanization or the resin won't stick.

I've used a metal prep (phosphoric acid) etched surface with good results.

Dont go away Pete
 

Does that mean you just throw the etch over everything, including the primer and galvanized areas and thats it? Or do you have to strip to bare metal first?

metal prep goes over bare metal. It oxidizes bare steel to a dull gray finish. I got a quart bottle from any old auto parts store, and put a pump spray top on from an empty laundry stain remover. If you have a tough rust converter type paint, it'll stick to that too, just rough it a bit first.