Hi
I have some serious imperfections in my mould which will need filled.

Using Gelcoat and wax works fine in small areas but I wondered if there was some other type of filler more suitable for larger surface imperfections - like a car body filler?

I would be using the mould to make a part to make another decent mould from (I know!!)

Thanks

Polyester fillers usually have very bad releasing characteristics. This can damage the gelcoat of yor new counter mould, wich would bring you back were you started. Even with several coats of release agent. Epoxy fillers work much better in that case.
Wrinkles usually can be repaired quite easily with gelcoat.

Thanks so much - this is the type of information that is so useful to us beginners!