Fiberglassing - polyester vs epoxy

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Dovii kid

Aimara
MFK Member
Sep 26, 2006
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Connecticut
I am currently in the process of beginning my plywood build. Build will be a 10x4 with external 2x6 bracing. Looking into waterproofing options and am planning to use resin and reinforcement. Afterwards planning to use sweetwater epoxy paint on top for further waterproofing and UV protection.

In my search reading a lot of the benefits of epoxy and some negatives to poly resin. Poly isn’t waterproof, Poly doesn’t bond well to plywood, poly will eventually delaminates from plywood, etc. That said I am still seeing a lot of poly resin used in koi ponds, swimming pools, etc and wondering why I couldn’t go this route as well. Any fiberglass experts out here that could give me some advice? Anyone used polyester on a plywood build? What are your experiences? Should I go with epoxy resin and cloth?
 
Definitely epoxy resin. Much superior product. Epoxy resins have come very far now days and if your not the best builder I would recommend a epoxy resin with a bit of flexibility
 
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If using polyester then you need a gelcoat. The gelcoat is 100% waterproof. Polyester is best for laminating wood epoxy is best for bonding parts together.
 
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Then there are a lot of boats that would sink or have saturated hulls. Gelcoat is waterproof. Boats are made of mostly polyester resin with gelcoat.
 
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