I have vac bagged some parts and they have come out nicely. My problem is however the clear gel coat and resin are too brittle and so I am going to use epoxy.
The last time I used epoxy in my polyester mould it seemed to print through onto the mould leaving resin printed onto the mould surface as no gelcoat to protect it.
What might have caused this and how can I avoid it without changing to an epoxy mould?
the mold has nothing to do with the print through. its just because you didnt use gelcoat. you can use polyester gelcoat with epoxy resins with no problems. just to be sure,i would let it dry well before laying up epoxy , but some manufacturers say to layup after the gel has b-staged.
Mold Release Wax… apply and buff, apply and buff…every 30 minutes. Can’t put all the wax coats on at one time because not waiting will cause the last coat of wax you just put on to be wiped off.
12 coats of wax on a new mold or one that you have not used in a long time.
If you use a thick epoxy resin you can brush that onto the mold surface in lue of a polyester gel coat. That will help make a smooth pourous free surface on your part.
Or… find a polyester gel coat that is compatible with epoxy resin. There are threads on the forum about it. Search feature 