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Epoxy or polyester?

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Hpr
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Epoxy or polyester?

Postby Hpr » Tue Sep 06, 2016 8:57 am

I need to fix my surfboard, but not sure whether to use epoxy or polyester resin. Is there a way to check what was used to make the board? Would it matter if I use epoxy on a board that was made with polyester resin? I mean, is the foam possibly different so the epoxy might dissolve it, or is the same type of foam always used?

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alamos_kiter
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Re: Epoxy or polyester?

Postby alamos_kiter » Tue Sep 06, 2016 9:32 am

Epoxy. Does not matter if the board is made of epoxy or polyester, for repairs always use epoxy. Poly does not bond well with old poly.

Only very cheap epoxies have dissolvents, you would not want to use those for a repair anyways.

Hpr
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Re: Epoxy or polyester?

Postby Hpr » Tue Sep 06, 2016 7:50 pm

Cool thanks a_k :thumb:

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Re: Epoxy or polyester?

Postby tautologies » Tue Sep 06, 2016 8:43 pm

alamos_kiter wrote:Epoxy. Does not matter if the board is made of epoxy or polyester, for repairs always use epoxy. Poly does not bond well with old poly.

Only very cheap epoxies have dissolvents, you would not want to use those for a repair anyways.
Maybe also mention that if you use polyester resin on polystyrene foam (EPS) board it will dissolve foam, whereas epoxy will not (its because polyester contains styrene).

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Re: Epoxy or polyester?

Postby alamos_kiter » Tue Sep 06, 2016 10:48 pm

Yep. for more wisdom check the board lady http://www.boardlady.com

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Re: Epoxy or polyester?

Postby iriejohn » Tue Sep 06, 2016 11:24 pm

If you want to make the repair lighter and easier to finish mix the epoxy with micro balloons - as long as the epoxy mix is at least as strong as the weakest material you are bonding then it will be strong enough.

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Re: Epoxy or polyester?

Postby William Munney » Mon Sep 12, 2016 1:23 am

Also use peel ply. It is a fabric you put on top of the epoxy when it is wet and peel off after it cures. Gives you a much smoother surface. The West Epoxy packets are pretty good for the typical small repairs and you can get all different sizes of fiberglass or carbon fiber cloth.

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Re: Epoxy or polyester?

Postby foam-n-fibre » Mon Sep 12, 2016 2:20 am

Are you going to paint over it, or does it need to be clear, or do you care what it looks like? If the board is clear fiberglass over the foam, then try to find surfboard grade epoxy, meaning some thing with UV inhibitors. West System will turn brown and ugly in the sun. Most other epoxies also will unless they were formulated for surfboards. Resin Research Epoxy is commonly used in the US, but I'm not sure what's available in other parts of the world. Filler like microballoons also needs painting over if you want it to look nice.

Peter


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