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chrisg
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Dravis (25/11/2014)
The big difference between using high pressure and high vacuum is what happens to tiny amounts of gas left in the resin/laminate .
A trapped bubble that would be microscopic under high pressure will be clearly visible in vacuum ...
So: If the tiny outgassing from the resin can not be moved away by the vacuum -- you get pinholes -this is why you need a good breather layer, perforated release film and a slightly resin-rich layup, before vac-bagging it.
De-gassing the resin before use also helps.Thanks for your time and help.
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Exocet
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Update, Bit the bullet and got a vacuum system. Made my Glass topped 'curing box' and made some flat panels over the w/end.   " alt="http:/ " /> 2 layers of C/F and 1 layer of 2mm Soric. and the results.  " alt="http:/ " /> This has given me the quality I was looking for, now to experiment with some more interesting shapes!
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Dravis
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The big difference between using high pressure and high vacuum is what happens to tiny amounts of gas left in the resin/laminate .
A trapped bubble that would be microscopic under high pressure will be clearly visible in vacuum ...
So: If the tiny outgassing from the resin can not be moved away by the vacuum -- you get pinholes -this is why you need a good breather layer, perforated release film and a slightly resin-rich layup, before vac-bagging it.
De-gassing the resin before use also helps.
"Sapere Aude"... Dare to KNOW!
The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...
103% of all people do not understand statistics...
Do not adjust our mind, theres a fault in reality :-)
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chrisg
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Hey quys new to forum and vacuum bagging cf and kevlar. I have made many plates with amazing finish and strenght. The only problem i am having is i get very small pinholes on face of plate. I have made plate under tons of pressure prior to vacuum and never had this problem. Can someone please tell me why I am having this problem.
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kiwimanz
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Another option that won't give you as glossy surface is to use is glue a sheet of Formica to some particle board. I have infused a ton of panels this way with great success. If you need to add heat, make up a tent over the layup with a tarp and use a heater with a fan to give even heat. Don't use melamine the blood stuff is porous.... don't ask me how I know this  Linz
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Dravis
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I would try three things: 1: apply a chemical release agent first, then a couple of layers of wax. 2: try using a sponge roller for the GC50, but spraying is best, brushing on does not work well.. 3: Vacuum will solve a lot of your problems, the EC infusion kit contains everything you need to do hand layup with vacuum bagging afterwards, or you can do infusion, both will produce panels with very nice finish, and even thickness. The kit can then be used to make a lot of other nice CF parts for your car ... 
"Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
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brainfart
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If you have spray equipment already you can try to apply the gel coat with it, at least for testing purposes. Clear gelcoats can me made sprayable with regular equipment by addition of some styrene (optional) and acetone. This means curing will take longer than usual. To overcome the fisheyeing only mist the released mold surface with the gelcoat on the first spray passes, maybe heat the mold. This will create small microscopic islands of gelcoat and the following passes will not separate from the mold surface anymore. You can also try to use another release agent. I have successfully made carbon panels with a hydraulic veneer press, one of these babies:  The press had heated plates for post curing, how convenient, and the resulting panels were absolutely void free. Maybe you have access to some woodworking business with such a press? The required pressure actually wasn't very high, but still quite a lot of excess resin was squeezed out. I think this could be done simply between some glass panels and particle boards weighted down with bricks etc. Try this first, if it doesn't work then go and get some vacuum equipment and bagging/infusion consumables.
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Exocet
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Guys, thank you for all your advice and ideas. Its been very helpful in increasing my knowledge. However, I must admit I'm still not sure what way to go. So I have tried to summarise my thoughts and would be grateful for any further thoughts/ advice. Thanks in advance  The problem 1.So I need to make 2 flat carbon panels approximately 2mtrs long by 0.5mtrs wide. These panels will be very much on show on the side of a car. So therefore I would like them to be as near perfect as possible.
So far I have wet laid on glass a number of flat carbon panels but a lot smaller approx 50cms x 30 cms. The surface finish has improved with practise. But the problems I experience are;
1. Using EC50 gelcoat, this streaks/fish eyes when applied by brush. As a result, I tend to put quite a thick layer on to try to prevent this. This results in an uneven gel coat on which to apply the carbon. I can see this unevenness in the carbon on the finished panel. 2. The second problem is despite ready trying to wet out the carbon I can sometimes end up with small air bubbles between the weave and the gel. This probably isn't helped by the uneven surface of the brushed on gel.
So I'm really worried about making large panels, as I can only think these problems will be multiplied by the area I'm working on.
The SolutionSo based on the above I thought that resin infusion would solve this problem??? as I believed it would;1, Ensure a even thickness.2, Remove any air from the process.
My panels are likely to be 2 x 200gram carbon fibre + 2 x 200 gram woven Glass Fibre + 1 x 200 gram carbon fibre (so hopefully not complex). Then Brainfart suggested that infusion was overrated.
Problem 2.This put me in a bit of a flat spin, as to go the infusion route is £300 for the basic kit. I don't want to spend £300 and be no better off! However,I also dont want to wet lay my panels and have to scrap them and the cost of the carbon and resin due to a poor finish.
My Questions.So I'm left with the following questions;1. Should I go the infusion route ?2. Am I over complicating this, a gel coat spray gun is £100 (I have a compressor, and can spray paint) so would the answer be to buy a gel coat spray gun and lay my gel coat down with this and then hand lay the carbon?3. What other options are there if any?
Sorry for a long reply. But I'm sure someone can help and asked the above.
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Dravis
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"davro" has the setup very nicely done ... As for the risk of fire, it is actually very difficult to ignite wood surfaces with a fan heater ... You may be unlucky and char the wood surface and get a lot of smoke and smell, but it is unlikely to catch fire. If you are working with epoxy There's really no need to use plasterboard or foil or the like, you will not need much more than 80 deg. C. Large areas of GC50 really needs to be sprayed ... Hand layup with vacuum bagging works just as well as infusion for flat sheets ..
"Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
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davro
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My ghetto heated glass table. I have the fan heater (thermostatically controlled) inside the box so it recurculates the hot air keeping the glass surface at around 70c - 80c depending how many blankets I cover it with during the curing process. Have produced many, many sheets using this ghetto table, also acts as a way to cure larger moulds on top of the table, and curing smaller moulds inside like an oven, very adaptable! 
David StevensYouTube: Comment | Rate | Subscribe InstagramComposite ProjectsBody Package for Dax RushRC Car Touring Body 1/10 Scale
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