Talk Composites - The Forum for Advanced Composites

Epoxy repelling on mould

http://www.talkcomposites.com/Topic25298.aspx

By AWOL - 2/27/2018 10:45:36 PM

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
By AWOL - 3/13/2018 2:15:45 AM

 
CaveDweller - 3/12/2018 2:20:58 PM
Defo wet the cloth out. Another possibility is to spray a clear gel coat into the mould first, its viscosity will allow it to stay where you put it and then you'll be able to stand a chance of applying your resin on the back of it and maintain a fully wetted surface.

I'm in the middle of such adventures myself for those occasions where prepreg or infusion arent on the cards.

Thanks for the advice CaveDweller, It's definitely a learning curve - but the passion is strong so I'll run a few test pieces over the next few weeks, then hopefully drop a nice infused piece on here soon-ish