Hi Ian,
Just to touch on a couple of the questions that you've raised on email on this same subject...
I'm completely stuck having thrown away 4 attempts now. I'm trying to make a 1mm flat sheet about 80cm x 50cm. I am using laminated glass as the mould. Attempt 1: Carnuba mould release wax. Epoxy gel coat. Then carbon with EL2 fast. The gel coat stuck like the proverbial to the glass and separated from the carbon after curing.
It's almost impossible to get wax to stick to glass so what's happened is that the wax hasn't stuck to the glass leaving you effectively applying gel coat to glass (which will stick like crazy). If the gel coat delaminated from the resin then the likelihood is that it had cured too far when you applied the resin to the gelcoat.
. Attempt 2: PVA release agent. No gel coat. Layer of EL2 allowed to go tacky, then laid up as normal. The best result, but a few areas of resin stuck to the glass. I think the problem here is I'm struggling to get a uniform coverage of PVA across a relatively large area.
Yes, that's exactly what's happened. PVA is almost impossible to apply to glass properly too. It will fish-eye away from the glass and that will be exactly what's happened in the areas where the laminate has stuck. The reason this was one of your 'better' attempts is because the PVA (where it did stick) is a none-repellent surface and so the resin (used in this case as a gel coat) didn't fish-eye away from it.
Attempt 3: Easy-lease agent. 5 coats as per instructions. EL2 spread as an initial layer. Fish-eyed into puddles of resin. Allowed to go a bit tacky then spread and touched up to fill the voids. Then laid up as usual. Whole lot stuck to the glass completely.
Well, like Paul pointed out Easy-Lease is too repellent to allow you to use a layer of resin (particularly one as low in viscosity as our EL-2) as a gel coat. As for why it stuck that makes no sense at all, I can guarantee that Easy-Lease will give you a perfect release of glass (we use it every single day to make all our flat sheets) so I would checking whether you completely cleaned all of the wax, pva and other contaminants off the glass (using a mould cleaner), whether you applied using cloth that was free of contamination and finally looking for anything really unlikely (but still possible) such as misinterpreting the instructions or (and it's been known) accidentally using mould cleaner instead of release agent (the bottles are very similar!). The bottom line is that Easy-Lease will certainly release perfectly off glass providing none of the above has caused a problem.
Attempt 4: Easy-lease agent. Coated with gel coat. Still some small fish eyes. As it was curing it was "crystallising" and not setting as a uniform layer. Viewed from above it looked more like a dry stone wall. Random lines forming. My gel coat (all the chemicals are yours by the way) is a sort of smoky blue and not clear. Could it have "gone off" in storage in my garage?
Normally we can get the epoxy gel coat to go down on Easy-Lease without fish-eying, you need to use a roller and make the layer as smooth and flat as you can. As Paul said, we don't use a gel coat at all and so we don't actually use this technique but it should be possible.
As for whether anything could be wrong with the epoxy gel coat, I guess it's possible if it's been very cold (i.e. freezing or near to freezing) in your garage. Also you need to consider shelf-life (12 months for the gel coat) and also whether the containers are tightly sealed (the hardener particularly is very hydroscopic and will absorb moisture and be damaged if the container is not tightly sealed. As for the colour, this doesn't sound unusual. The 'Clear Epoxy Gel Coat' (much like many other types of clear gel coat) doesn't actually look very clear when it's in the container. It does look a sort of smoky blue as you describe. Once it's on the part where of course it will only be very thin, it looks very clear.
The bottom line is that you're better off producing flat sheet in the way that Paul said, using no gel coat. With the right technique it's perfectly possible.
What Paul didn't mention, but probably meant to, is that we always use a Peel-Ply on the reverse of the sheet. This allows us to squeegee excess resin out of the laminate without disturbing the carbon underneath. You get a lighter sheet and a much better surface for bonding on the reverse.
Matt StathamEasy Composites / Carbon Mods - Technical Sales