Gel coat and Epoxy if done correctly will it work?

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Gel coat and Epoxy if done correctly will it work?

Gel coat and Epoxy if done correctly will it work?

Author	Message
Fasta	Fasta posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	Using epoxy wont create excessive heat with just 4-5mm thick. Using CSM builds thick laminates easier, with epoxy you need to use more expensive cloth and many more layers of it too. Tailoring the cloth and wetting out the extra layers will take much longer. I know of old school mould builders who would use regular polyester resins with light surfboard cloth materials but lots and lots of layers built up over many days or weeks. This way the heat and shrinkage was reduced and the mould had a high fibre/resin ratio making it stiff and stable compared to a CSM laminate. Fastacraft Facebook page Edited 10 Years Ago by Fasta
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fastboats	fastboats posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 9, Visits: 94	OK I searched the csm and now understand it the binding agent that causes problems with epoxy.
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fastboats	fastboats posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 9, Visits: 94	OK so the heat generated would be the problem with more then a few layers of epoxy on a half layup mold? What's the reason why you can't use csm with epoxy?
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Hanaldo	Hanaldo posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Because it's not good practice to lay all your reinforcement in one hit, like you can do with rapid tooling resin. Theoretically you could use a low exotherm resin like an infusion resin, but that then comes with its own issues. There's also the problem of what type of reinforcement to use; you can't use regular CSM so you either need to use powder bound mat (which is a real mongrel of a thing) or you need to use woven cloths, in which case you need to consider fibre orientation etc. All these things just take a bit more time, it just isn't as straight forward as rapid tooling resins.
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fastboats	fastboats posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 9, Visits: 94	I understand what your saying for the most part. And thanks for the information. One thing I don't get yet is why epoxy molding will take so much more time? Yes it's more expensive I see that but why the extra time? My pattern is now built and smooth. Waiting on paint then the paint to fully cure. After that I would like to start making the mold. It dose sound like the unimold system will be the best way. And it's a proven system. But still curious about everything. I can't wait to dive in and start trying this! Thanks again.
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Fasta	Fasta posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	The uni mold like many others is a no shrink system. It should be good. (note I have not specifically used uni mold but I do use another similar system). Basically these modern mould resins are filled with ?? and go a cream colour when the cure as well as getting reasonably hot 40-50 deg C but they are supposed to do this. In the past moulds were made from lesser resins and moulds needed to made very slowly and built up with just a couple of layers at a time so that they did not shrink. Then left for weeks if possible before demolding. Well reinforced etc etc. Things are different now. Epoxy will make great moulds too but they sure will cost more and take longer to make. Maybe not such a big deal for small moulds but very expensive for others even if it is just 3 or 4 square meters. If you really wanted to use epoxy then I would use a full epoxy system with epoxy gel coat too rather than make an experiment with vinyl ester gel coats. As I said last, a long lasting mould will mostly be dependent on a good hard (well cured) non porous gel coat and your release system along with good process habits etc. Experience helps too. Test things as you go with samples and prove your release to yourself before committing to bigger things. Fastacraft Facebook page
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fastboats	fastboats posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 9, Visits: 94	OK I'm sorry I missed a post. I'm looking to make a long lasting mold. I was reading that the non epoxy molds shrink and Crack so I was under the impression epoxy would be the best. The boat part I want to make has to be epoxy for weight savings and strength. But the mold I want to use whatever will make it long lasting and not shrink. I want to resin infuse the part with no oven.
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Fasta	Fasta posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	In my experience the first and main thing that makes or defines the mould is the surface quality being the gel coat, plus how well it releases and continues to release. So careful application of release systems and processing in general also matters. The usual thing to let moulds down is the surface breaking down or getting damaged. Far less of an issue is the fibreglass material the mould is made from although it is nice to have a mould that remains true and without shrinkage. Uni mould is a no shrink material so that should be fine. If your mould is going to be used in an oven with pre pregs then you need be aware of differing expansion rates in the materials so if you mix carbon and glass then the mould may change shape. Also any air bubbles can expand and delaminate the laminate. An all fibreglass mould will at least expand evenly at about 1mm per 1m whereas an all carbon mould will remain the same. A mixture of carbon and glass will fight each other. The movement in an all fibreglass mould is minimal and even so you just need to design for this 0.1% if it matters. In the end all this stuff needs to be tested and proven for your own peace of mind. If another material or method works for you then great. fastboats (20/10/2015) So I could get some gc50 color it as I want then apply to a surface (mold release applied first) wait for tack the add layers of fiber glass or carbon fiber in a wet out application to build a mold? Then when building part do the same but resin infuse the layers? All with epoxy. Is this the best way to build a mold that will last? Fastacraft Facebook page Edited 10 Years Ago by Fasta
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fastboats	fastboats posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 9, Visits: 94	So I could get some gc50 color it as I want then apply to a surface (mold release applied first) wait for tack the add layers of fiber glass or carbon fiber in a wet out application to build a mold? Then when building part do the same but resin infuse the layers? All with epoxy. Is this the best way to build a mold that will last?
	Reply Like 2
Fasta	Fasta posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	I am curious why the original poster want to use epoxy resins. I have not used the specific Uni mold system but it appears to be the same or similar to others in that it has vinyl ester gel coat and filled no shrink laminating system. They are a really good system and make great moulds. Unless you are chasing some extreme temperature resistance I would just use uni mold. Using an epoxy laminate will mean using cloth materials which cost more, epoxy resins which cost more, and probably 4-5 times as much labour in the layup. Fastacraft Facebook page
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