Breaking in mould. Does anyone do it? My moulds stuck!


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carbon man
carbon man
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So Iv had 3 moulds stick on me now. I'm using tr108 wax as it's advertised to reduce fish eye when gel coat goes into the mould.

I have tried exact instructions on tin 8 coats and then leave over night before another coat.

Also tried 5 chem release followed by 2 tr108 wax.

I brush in polyester gel coat let dry. Lay up and  infuse with epoxy In2 resin and cure in mould at 60deg straight away for about 8 hours so it gels fast in the event of a leak.

The shiney parts of the mould released just about but everywhere else stuck like s***!

But should I be laying in a layer of fibreglass and pulling that out once cured to break in mould first?

Any help appreciated.
Edited 5 Years Ago by carbon man
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carbon man
carbon man
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Hanaldo - 6/19/2021 12:05:30 AM
carbon man - 6/16/2021 8:46:22 PM
I brush in polyester gel coat let dry. Lay up and  infuse with epoxy In2 resin 

I think this will be your issue. You can't use epoxy resin behind a polyester gelcoat, it won't bond properly. Gelcoats are designed to not fully cure, and they need the chemical reaction between the gelcoat and the laminating resin to cure and make a strong bond. Epoxy doesn't react chemically with polyester, it is a purely mechanical bond, and because the gelcoat isn't cured properly the mechanical bond strength is very poor.

So your issue probably isn't so much a release failure, but the fact that the surface tension between the gelcoat and the mould is higher than the bond strength between the gelcoat and the epoxy resin. 

Either switch to an epoxy gelcoat, or switch to a polyester/vinyl ester laminating resin.

Hi, some of my moulds that have had a couple of pulls are now fine and appear to have bonded to the Scott bader cystic gloss coat well? It's just on the new mould I'm having trouble.

Are you UK? I can't find vinyester infusion resin. Only at East Coast fibreglass but they say its not clear resin.

Thanks

GO

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