Epoxy repelling on mould

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Epoxy repelling on mould

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AWOL	A AWOL posted 7 Years Ago HOT Topic Details
A Group: Forum Members Posts: 9, Visits: 72	Hey Guys, We're playing around with a few moulds at home (Australia) but are having a consistent repelling issue from the Epoxy when we go to lay our carbon (240gsm 2/2 twill) Pretty much pulling our hair out, we're convinced it may have something to do with our moulds but thought we'd seek opinion from the global community. We're wondering if it is because of a polyester gelcoat mould vs epoxy problem? Anyway - here's what we have; Mould build - the moulds always seem to be a good representation and quite solid Release waxed mould - 5 times Laid down polyester gelcoat (waited 24hours) Laid down 1st lightweight fibreglass adhesion coat (waited 24hours) Laid down 5-6 heavyweight fibreglass layers Wait 2 days - pull mould - reverse mould looks great, detailed representation Laying Carbon - temperature is approx 20-25C Waxed mould - 5 times, waiting between coats PVA release agent - light coat - wait 30 mins til applying epoxy Epoxy is West Systems with 205 hardener 5:1 Yet when we go to brush on epoxy it repels, ie doesn't seem to want to stick to the prepped surface Note: when we skin items we have no issues with the epoxy We're still noobs in this hobby, so will appreciate any input kind regards Justin
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AWOL	A AWOL posted 7 Years Ago HOT Post Details
A Group: Forum Members Posts: 9, Visits: 72	+x Hanaldo - 3/8/2018 11:06:07 PM We've had mid-30 degree ambients in Perth lately, so it wouldn't be impossible to PVA that mould inside 30 minutes. If the PVA was touch dry when you moved ahead then it wouldn't be a problem. Realistically, that issue would present itself in a different way, it wouldn't cause seperation issues. But on the topic of PVA, are you spraying or brushing it? I can't remember if you mentioned in your first post. The results will be infinitely better if you are spraying it, so if you don't have spray equipment I would recommend grabbing a Preval sprayer from Supercheap and applying it that way. To me, it sounds like the PVA isn't a complete film on the surface and you are mostly applying the epoxy to the waxed mould surface? In which case, a low viscosity resin is going to seperate and pool very easily. I would suggest using a thicker laminating epoxy, and you could try wetting out your carbon on a sheet of plastic before you apply it to the mould. Use a squeegee to squeeze out excess resin, and then just take your time making sure it all conforms to the mould surface. You will likely still get a few voids because this isn't an easy shape to do without vacuum, but it isn't hard so hard to fix compared to what you have now. We have just brushed on the PVA, although we recently picked up a Preval sprayer so will definitely be using it on our next attempt I like the idea of pre-wetting out the carbon on some plastic first, we may try that also Although I am now keen to attempt a few vac bagging projects (quite a bit smaller) and may revisit this again once we can master vacuum - because as you mentioned, it is quite hard to get it to hold on all the shape
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