Hello guys, 

I'm having trouble de-moulding one of my molds.
Mould made with polyester and the piece was infused with epoxy resin.

What is the best solution to reuse this mould and continue infusing with epoxy resin?

PVA is a good solution? works well with the infusion process?

Epoxy in polyester molds sometimes can be a bit tacky. Even if both mold and part are cured properly. But the really good release agents, like easylease (i guess, never used it) should should still be fine. I had some issues with standard wax, then used a chemical release agent (from hp-textiles, wich seems to be differnt to easylease, aß it is water based, but not like pva) als never had Problems again. I once read, that this is caused by a light porousity of up resin combined with the excellent bonding propertys of ep resin. So pva should solve the problem, too.

Epoxy into polyester moulds often causes a problem - especially on newer moulds or in cases where the release agent application is not perfect.  Any new or newish moulds are not recommended to be used for infusion as the very slight styrene outgassing combined with epoxies affinity to bond to polyester would almost mean you would gate a guaranteed "sticker".

You can solve the problem using an epoxy compatible polyester gelcoat or by using PVA mould release.

Older moulds are less likely to suffer in the same way but it is worth testing on the flange or similar first.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

For some months I have done this mold. I believe that for this reason will not have any problems with styrene.

I am currently using a hydrocarbon-based chemical mold release and yet one of my infused parts got stuck in the mold.

I will do the infusion test using PVA mold release.