Alternating epoxy and resin

Discussion in 'Fiberglass and Composite Boat Building' started by makobuilders, Feb 13, 2017.

  1. makobuilders
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    makobuilders Member

    Is there an issue with adding layers of epoxy-saturated fiberglass with typical resin-saturated cloths? Or perhaps reinforcing layers of kevlar that are laid down with epoxy instead of resin?
     
  2. upchurchmr
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    upchurchmr Senior Member

    What does resin mean?

    Is this polyester resin?

    What is "cloths"? This is something different than fiberglass cloth?
     
  3. makobuilders
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    makobuilders Member

    Yes I'm referring to mixing a layer of fiberglass cloth (or kevlar) that is mixed with epoxy in a normal layup of fiberglass cloth set with polyester resin.
     
  4. gonzo
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    gonzo Senior Member

    To start with, the amine in the epoxy inhibits the cure of polyester resin. Secondly, the physical properties of the resins are very different. It would be better and cheaper to stay with just one type of resin. What is the Kevlar for and where would it be placed in the laminate? Vinylester resin could be a more appropriate material. However, you need to engineer the laminate for the application.
     
  5. upchurchmr
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    upchurchmr Senior Member

    Can you tell us what you hope to achieve with mixing the two resin systems?
     
  6. rwatson
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    rwatson Senior Member

    If you are trying to save costs, you could do the whole hull in Polyester, and a final exterior coat in Epoxy for waterproofing
     
  7. rxcomposite
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    rxcomposite Senior Member

    If you really want to whittle down cost and still have a superior product, the practice is to use Vynil Ester on the outside (wet side) after gel coat. This layer is resin rich with CSM 228 for a start then CSM300 or 450. 2 to 3 layer will provide a tough and superior water barrier outside, preventing osmosis. This can be followed by ISO resin/fiber for the succeeding layer. I get by with a good Class approved ISO resin but VE with a higher cost is better.

    Finally, for the bilge side or inner layer/last layer, it should be a resin rich laminate such as CSM. A regular ISO resin will suffice. Purpose is twofold. Water barrier and to provide a good grip for the secondary bond of frames and stiffener.

    Never interspace poly and epoxy laminate. The good practice is when you have poly resin laminate, you can bond epoxy over it but you cannot use poly after as it does not bond well to epoxy substrate.
     
  8. makobuilders
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    makobuilders Member

    Actually it was just simply a question about whether epoxy can be "mixed" with resins. Nothing to do with saving money. This followed to a conversation I had about sandwiching a band of kevlar within the glass cloth layers at the waterline to create an ice belt.

    Thanks for the clarifications.
     
  9. upchurchmr
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    upchurchmr Senior Member

    Ice belt in Qatar?

    Kevlar works fine in Epoxy.
     
  10. makobuilders
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    makobuilders Member

    We snow ski in Dubai :)
     
  11. mydauphin
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    mydauphin Senior Member

    I have built things using polyester and epoxy mix together. The polyester gives it rigidity and is the center core material, it is then covered on all sides with epoxy. Epoxy will bond to cured polyester resin. So you can make something out of resin and then cover it fully with epoxy. I am building a waste tank with this method right now. It was foam, covered with epoxy, then we got rid of foam and covered everything with epoxy. Waste smell goes thru resin since it has pores, it won't go through epoxy.
     

  12. upchurchmr
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    upchurchmr Senior Member

    glass gives rigidity, not the resin, no matter what it is.

    Your example has no polyester?????
     
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