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AdamHutchin
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Group: Forum Members
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Hi, I've been reading through the forum but can't find the specific answer I'm looking for so wondered if anyone could advise? I have some previous experience (although quite a long time ago now!) of working with pre-preg carbon and wet lay up glass but have yet to try wet lay up carbon. When I used pr- preg carbon, it was just laid straight into the mold and vac-bagged. When I used glass, I first coated the mold with a gel coat, allowed it to go tacky, then laid in the CSM. With wet lay up carbon, I'm unsure of the correct process here and there seem to be different answers around the internet. I know it's a bit of a noob question but I thought I'd post here as this is where I'll be ordering the materials from and there are often differences between manufacturers products to consider too. My aim is to produce a few cosmetically pleasing, lightweight, non-structural parts. I will be vac-bagging the parts and have the resources to cure at elevated temperatures. My question is, can I achieve my goal by applying a layer of epoxy to the mold and proceeding with the lay up or should I allow that coat to go tacky before proceeding? I have seen different recommendations from different sources. Alternatively do I need a separate gel coat? I intend to use EL2 Epoxy Laminating Resin and "Easy-Lease" release agent, the mold contact surfaces are a mixture of mild steel and chrome. Thanks in advance.
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Hanaldo
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If you're using Easy-lease, you'll never get the laminating resin to apply evenly as a coating without separating. Better to use EC's GC50 gelcoat as the initial coating if you want a gelcoat. Alternatively, brush the laminating resin into the mould and proceed with laying up the carbon. Make the first layer quite resin rich, then do the others as normal before bagging it all up.
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AdamHutchin
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Group: Forum Members
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Ah OK, thanks for the quick response. The easy-lease isn't a necessity, I can use other release agents if you think others would be better suited, it's just I had heard positive things about it so thought it worth a go.
I might give that GC50 a go then as I'd like an aesthetically pleasing finish if possible.
Do you know if the GC50 can be vac bagged? I'd heard that some polyester resins aren't suitable for use under vacuum.
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Hanaldo
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Group: Forum Members
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No no, Easy-lease is great. It's just a high-slip release agent, so it lowers the surface tension of the mould surface meaning any liquids you put on it will separate (fisheye). It's just something you have to watch out for. GC50 can be vac bagged fine. The issue with bagging polyester resins is when laminating with them, you can boil the styrene off under vacuum which causes problems with curing. No issue with GC50 or other gelcoats as you let them cure before laminating.
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AdamHutchin
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Group: Forum Members
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Ah of course, that makes more sense regarding the gel coat. OK, I have several things to lay up, some are relatively simple and flat, one has several return surfaces in a 3 part mold which means that it will always have at least one vertical surface and possibly even an "upside down" return to close it off. If go down that route then I guess the easy lease wouldn't be suitable. What would you suggest? PVA? Wax?
Thanks again for your input.
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Hanaldo
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Group: Forum Members
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What I do when I'm using in-mould coatings, is apply the chemical release agent as per the instructions (so 5 coats of Easy-lease I believe). Let that sit overnight if you can, but at least an hour. Then apply 2 coats of NON-SILICONE release wax over the top, and be REALLY gentle with your application. Don't buff it too hard, you really want to buff it as lightly as possible so you can see the gloss return but you aren't buffing off your semi-permanent release agent. What this does is it raises the surface tension again slightly. So if you are using the GC50 which is formulated to be thixotropic and avoid sagging/separation, it makes it a lot easier to get a good application, even on vertical surfaces. Are you able to spray the GC50 at all? That really does make it easier. You should be able to brush the GC50 using the semi-perm/wax combination as well, but the issue then is its very difficult to get a smooth finish with a brush, and you can end up distorting the weave of your carbon which creates an odd appearance under the gelcoat. I'd really recommend spraying any clear in-mould coatings.
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AdamHutchin
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Group: Forum Members
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Unfortunately I don't have the facility to spray the GC50 at present and I can't really justify the additional expense of a spray gun at the moment.
OK, I'll give your recommendations regarding the release agents a go. Thanks for all your advice.
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Warren (Staff)
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GC50 can be brush applied for wet lay applications. We don't recommend brush application where vacuum bagging or resin infusion is being caused as the fabric is pressed tightly against the brush marks on the gel distorting the weave pattern slightly. On wet lay this isn't a problem as the fabric floats ontop of the initial layer of resin and as such is not pressed into the brush marks and hence does not have the same distortion.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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AdamHutchin
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Group: Forum Members
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Thanks Warren, I actually intended to vac bag the item after laying it up so it sounds like I need to consider spraying. I don't really paint enough, or lay up enough stuff to justify buying a spraygun for either application, I contacted a spraygun supplier to see if they have an entry level spraygun suitable for the application of both normal paint and gel coats like GC50, if such a thing exists then I'd probably get enough use out of it to warrant buying one. The spray gun manufacturer emailed me back asking for " a TDS that guides to correct fluid tip choice?". I looked at the TDS available for GC50, and unless I'm missing something, I couldn't see any guidance on this. Perhaps you could advise?
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Warren (Staff)
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Group: Administrators
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We would recommend the use of a gelcoat cup gun such as our Gelcoat Spraying Cup Gun
As standard it comes with a 4.8mm nozzle which we find is fine for spraying GC50 and other similar viscosity gelcoats. It does take a bit of practice to get the technique right so we would recommend spraying on a scrap panel to start with as you may well need to adjust the compressor. The Gelcoat Spraying Cup Gun should be used with an air feed pressure of between 60 and 100 psi. The gun will use around 5.8cfm at a typical 80 pressure of psi.
Warren PenalverEasy Composites / Carbon Mods - Technical Support Assistant
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