Help with Resin and Epoxy

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Capn Klaus

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Sep 23, 2009
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Hello all,

I was at the local fiberglass shop here in Calgary and was talking to the experts there on fiberglassing my stringers and transom. Here is what they said to do. Since my boat is a 1976 era boat, it was put together with resin. Epoxy and resin apparently don't like each other...can cause delamination. They suggested I use resin for all fiberglassing BUT use epoxy for all gluing...transom plys, transom to outer skin, bedding material. AFTER I have fiberglassed the stringers and transom, I am to put a coat of Gelcoat overtop of this to give an extra seal to moisture penetrating the resin as they state resin is only water "resistant" not water proof.

I should also point out that I will be spray foaming below the deck so there will be no open spaces.

Any thoughts on the above procedure would be greatly appreciated as I am ready to purchase my materials.

Thanks in advance,

Klaus
 
ondarvr

ondarvr

Supreme Mariner
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11,527
Re: Help with Resin and Epoxy

Capn Klaus said:
Hello all,


Any thoughts on the above procedure would be greatly appreciated as I am ready to purchase my materials.

Thanks in advance,

Klaus
Click to expand...


There are many thoughts on this subject that have been discussed in great detail in this forum. Your best bet would be to do search here and do as much reading as possible.

Yes, what they told you is fairly accurate, although you don't really need to mix and match resins, it can make it more difficult.
 
erikgreen

erikgreen

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Jan 8, 2007
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Re: Help with Resin and Epoxy

To confuse you a bit more about what you heard and some of the things you'll read here, the name "resin" can apply to either epoxy or poly or even vinylester.

To translate from what you heard, replace the word "resin" with the word "polyester resin" which means the standard "fiberglass" resin. Generally when we talk about epoxy or poly we type those, and "resin" can mean either one.

To add to what ondarvr said, you can use either one for your boat work. Here are the rules:

* You can apply epoxy over poly resin
* You can apply poly over poly resin, but it's weaker than epoxy
* Poly resin will NOT stick to epoxy resin in a useful way

For gluing things epoxy grabs harder, that's why they said glue things with epoxy and use poly for the other stuff.

Generally if you use good techniques of surface prep (sanding, cleaning, etc) poly will work just fine for your boat repair. Epoxy will work too, and will be stronger, but also cost more, and you can't layer over it with poly later.

Erik

If there isn't already an extensive sticky for this question, there sure should be :)
 
cedarjunki

cedarjunki

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Aug 23, 2007
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Re: Help with Resin and Epoxy

erikgreen said:
Epoxy will work too, and will be stronger, but also cost more, and you can't layer over it with poly later.

Erik

If there isn't already an extensive sticky for this question, there sure should be :)
Click to expand...

will cost alotttttt more!!!! was originally built with poly, and i must say whatever /however you do it, it may be built better than it was at the factory anyway. i agree on the sticky!
 
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Capn Klaus

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Sep 23, 2009
Messages
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Re: Help with Resin and Epoxy

Thnaks guys,

Money is always a consideration...and if the poly resin will work just fine, than I think I will follow the guidance of the shop. Any comments of the Gelcoat over the poly for making the poly water proof??

Klaus
 
bigredinohio

bigredinohio

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Re: Help with Resin and Epoxy

Good luck and be sure to post some pictures.
 
ondarvr

ondarvr

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Messages
11,527
Re: Help with Resin and Epoxy

Capn Klaus said:
Thnaks guys,

Money is always a consideration...and if the poly resin will work just fine, than I think I will follow the guidance of the shop. Any comments of the Gelcoat over the poly for making the poly water proof??

Klaus
Click to expand...

Nothing is water proof, just varying degrees of water resistance, good gel coat helps when a laminate is submersed for long periods of time, on trailer boats it wouldn't make a huge difference if the hull had no gel coat on it at all.
 
erikgreen

erikgreen

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Jan 8, 2007
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3,105
Re: Help with Resin and Epoxy

Generally speaking, I think you'd want to coat the new glass with something to protect it. Technically poly is porous when hardened, but that's kind of like saying a battleship, being made of steel, will rust. It's true but not really a worry. Using a layer of mat on the surface of the new glass will help (it goes every which way, avoiding creation of pin holes) and putting a coating on the glass will seal it more or less permanently.

Gelcoat is standard, relatively cheap, and fairly tough. But, it's not paint.. it takes a tremendous amount of work to make it flat and shiny when you're not using it in a mold. If that doesn't bother you, it's a decent choice.

Other than gelcoat, there are a lot of good marine paints around that are relatively easy to get a nice shiny finish with, so those would be a good alternative.

Erik
 
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Capn Klaus

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Joined
Sep 23, 2009
Messages
23
Re: Help with Resin and Epoxy

Thanks for the info. The Gelcoat is on the inside of the boat hull so I'm not worried about appearance as this will be covered by the decking. (I will also be spray foaming the entire below deck area other then a few storage compartments). The outside of the hull will be painted with a polyurethan paint.

Thanks again,

Klaus
 
tdrudd87

tdrudd87

Petty Officer 1st Class
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May 28, 2009
Messages
288
Re: Help with Resin and Epoxy

I'm guessing you have pro equipment? Many here who foam use 2lb pour in.

Terry
 
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jonesg

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Feb 22, 2008
Messages
7,174
Re: Help with Resin and Epoxy

Bilge paint is a lot easier to deal with than gelcoat.
 
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