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Release agent for foam in polyester mold

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Release agent for foam in polyester mold

Old 09-02-2019, 02:25 PM
Fredrik holt1
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Default Release agent for foam in polyester mold

I dont really know a forum for this, so ill ask here and see if someone knows.

I have an rc airplane made from foam. I want to make a copy from carbon fiber, using a mold from polyester. I dont know what sort of release agent i can use that does not get soaked in, and ruin the foam. I also want to make touring car body shells with the same materials, so preferable something that works for plastic also. Do anyone know a release agent that works? Alternatively tips to stop the foam from soaking without ruining the plane? Thanks for amswers!
Old 09-03-2019, 03:12 PM
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There is no mold release for foam. Typically you want a hard non porous surface and then your release would be a combination of wax and PVA. Polyester is also not a good material for a mold. It tends to shrink and warp. You also run into a phenomenon called " styrene mitigation " which in more cases then not prevents the release from working properly. The more appropriate resin system for mold making is Epoxy laminating resin.

For your actual parts carbon fiber is not going to be the best choice unless you are willing to spend a ton of money both buying the light 1K fabric and then tossing a lot of parts in the garbage as you learn to use it. I advise against using CF as the main fabric unless you will be vacuum bagging your layup. For making models lightweight fiberglass cloth yields plenty of strength and can actually be lighter than CF. Reason being that CF fabric is usually available in 3oz and 5.7oz weights. CF will also require about 30% resin content whereas fiberglass can be as low a 20% without sacrificing too much weight. There is a good thread that includes mold making in the pattern section titled " Pattern Biplane ". It is well worth the read.

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