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?

This isn't the first time I have heard of wax creating voids and spots where epoxy simply will not go. Did you have any clumps or small "hills" of wax sitting on the surface of the aluminum? Or did you buff it all off? It sounds to me like there was too much wax left on the aluminum. If you can post some pictures of the carbon piece that came out that would be great.

As far as the temperature goes, 12 degrees Celsius is pretty cold for epoxy. I believe for most epoxies you normally want no less than 22 degrees. The lower the temperature, the higher the viscosity (thicker) it will be, which usually entraps bubbles, but in your case, it sounds like they are not the usual bubbles that every epoxy user tries to fight off. That being said, 12 degrees seems cold enough that I would think the epoxy would take forever to actually cure.

It could also be an incompatibility between the brand of resin and brand of wax - maybe they slightly attack each other? I saw on a forum once to be sure the mould release wax is a pure carnauba wax (which I assume all mould release waxes are). Hope this helps.

-Mike-

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

Mat. thanks for a very thoughtful and helpful reply. What I am after is a smooth clear finish. So infusion would seem to be the best answer. But Strength is not important, so if I don't want to buy all the extra stuff can I lay up on easylease, use vac bag straight on top of peelply only, vac till cured, remove peelply, add a coat of resin to smooth out the top, wet flat and varnish to shine???  (work is free, parts cost pennies)

Hi,

so if I don't want to buy all the extra stuff can I lay up on easylease, use vac bag straight on top of peelply only, vac till cured, remove peelply, add a coat of resin to smooth out the top, wet flat and varnish to shine?

In theory, just about, yes. However, the amount of work (even if it is free) and the difficulty of the task of applying resin then flatting and polishing up to a smooth shiney finish is so difficult and large that I would really recommend you don't go down this route.

If it's a one-off job and you want to avoid the cost of a catch-pot for example then create a ball of breather in the way of the vacuum line in the bag and so if you have excess resin heading towards your vacuum pump then this ball of breather should hold it off for quite a while. If it comes to the crush and some resin is making its way towards your pump then you can always clamp it off before it gets there. The only other things you need are infusion connectors (a few pounds each), some mesh and some spiral; that's it and you'll be able to make a perfect panel. Use Easy-Lease as your release agent. It's only a little expense and you'll get great results. Doing it the 'hard way' that you describe is pretty much doomed, even though in theory it's possible.

--Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Mat. Thanks again. The cost issue is really about the 5L EL2 I have opened and used just 200g out of, which will now go to waste. However the thought of perfect lightweight panels is tantalising. your tech advice service is second to none. Thanks again.

You're welcome!

Try infusing using the EL2 Laminating Resin. It will infuse slower than the IN2 infusion resin but it will still infuse (they're from the same family of resins). You will need to use a SLOW hardener (so if you purchase the FAST hardener then you'll want to pick up some of the AT30 SLOW to use with the resin instead) which will give the resin plenty of time to pull through before it gels.

--Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Mat.  Have taken the plunge and ordered the rest of the kit to infuse exactly as you advise. Will let you know how it goes.

Hi Matt
I was talking to a epoxy manufacturer in LA about viscosity. He said that it would be Ok to add up to 8% acetone to the infusion resin to reduce the viscosity and reduce surface tention that can cause pin holes. I haven't tried it yet but will. I was wondering if you have ever heard of doing this or had experience with this technic?
Fred