Restoring 1970's fibreglass bodied (and chassis) car.
sanding down to gel coat, there are star cracks in the gel coat. I believe using a flexible epoxy might be a  suitable way to repair the cracks after gently opening then out with a rounded burr (rather than sanding whole area to mat and re mat/glassing?
Could you advise please and also recommend a powder filler to include in the resin?

Any advice gratefully received.
Thanks,
Neil Jones

It depends why the cracks appeared?  There aren't any flexible epoxies that you will be able to easily sand and blend in to the repairs.  Many good quality epoxies may well be less brittle than the polyester and offer what you need. 

Other wise some extra reinforcement on the back to stop flex will help before doing a "conventional" gelcoat repair, preferably with a colour matched gel.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant