Just tried my first flat sheet 195g 2x2 c/f, and failed. I am using a polished aluminium table 2.4  x 1.7 Metres, No 8 wax, No 2 resin. I want a single thickness for decoration only. I waxed the Ali sheet and then tried to coat with epoxy, it kept producing pinholes which quickly opened up to bare circles the size of a penny. I brushed it over several times and gradually reduced the number of void circles but clouded the resin here and there, I assume with wax. I did press on and finish the sheet with Vac but had a persistent very slow leak, I just re pumped every 20 mins for 3 hours. The finished sheet (1/2mm thick) also shows tiny voids where the weave crosses. Perhaps I made some schoolboy errors here but a few hints would be much valued. I am wondering if everything was too cold at 12 deg?

Thanks for that. sorry I have been so long replying, been away. I have taken a photo and blown it up, and can now see  the dreaded bubble attack. So must sort the vacuum. The discoloured patch is where I think the epoxy picked up some wax. easycomp advice page says 'lightly wipe over to remove swirls' which I did but the swirls didn't fully go.  So was there too much wax? I can't show the not flowing issue, I dripped some new epoxy in the holes just before laying the cloth which seemed to work. Should I polish the wax more robustly next time?? It was cold, It took 3 1/2 hrs for the first coat to go tack dry.

Hi EZSailor,

Sorry for my delay in replying - I wrote you a whole essay in response to this question a week back but must have closed my browser without hitting 'Post reply'. The pain!

The gist of my reply was....

Firstly, temperature. Although it's not a good idea to be working at 12'C and all our cure times and performance properties (and tests) are based around 20'C. Really, you should aim for at least 18'C where you're working. I don't think the temperature caused the problems you've experienced but it's likely to cause other problems down the line so watch out and  maintain a decent working temperature.

*If* you want or need to use a clear layer before your reinforcement then this clear-layer needs to be a gelcoat, not a resin. Resin will always fish-eye away from a repellent surface like wax, I would also certainly recommend you use a Chemical Release Agent instead of wax on your flat surface; we always use Chemical Release Agent for our flat sheet production, I don't think we could make flat sheet properly without it.

You also need to consider what it is that you want to achieve with this gelcoat - is it for (1) UV stability, (2)polishability, or (3) to solve problems with 'pin holing'. If it's '1' or '2' then you would probably be better served with an epoxy compatible polyester gelcoat like our GC50. If it's for '3' then you won't find that a gelcoat (or clear resin layer) will solve the problem of pin-holing, it will simply move the problem down below a thin layer of resin, creating unsightly trapped air bubbles instead of pin-holes. To solve '3' you need to change your lamination technique.

As for the pin-holes themselves, this really is part of a painful trial and error process that always accompanies vacuum bagging (rather than resin infusion). It's almost unheard of to be able to vacuum bag a laminate like that and get a pin-hole free perfect surface first time and more than likely, even with some playing around (vac pressure, bagging stack, resin quantities) you'll pretty much never get that perfect surface you're after. The only reliable solution (when you're wanting to produce cosmetic quality surfaces) is resin infusion. If you've got vacuum bagging equipment then you're only a few bits and pieces away from a resin infusion setup. My advice would be to take the plunge on that.

I hope this helps and look forward to working with you some more.

--Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales