Epoxy over well sanded Gelcoat?

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APLJaK
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Epoxy over well sanded Gelcoat?

Post by APLJaK »

Hi, Naive question perhaps.

I am repairing the keel of a small skiff (8') for a friend. Previously someone used mat and tons of fiberglass resin and made a big mess. I have ground off the mess and would now like to use 2 x 6" 12oz tape and epoxy resin (System 3 Silvertip). The boat originally was finished in a green gelcoat. I have removed much of the gelcoat in the repair area and what remains is well sanded at 80 grit. Can I start the repair over this, even though I am not 100% back to the original glass, or should I keep sanding?

TLDR; Will epoxy resin bond over a well sanded bottom that may still have some gelcoat showing?

Better ask than find out the hard way. Thanks for any advice



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Re: Epoxy over well sanded Gelcoat?

Post by jbo_c »

I’ve done it successfully. I don’t think I’m an outlier.

As long as you’re down to solid stuff with no blisters or adhesion issues, I’d say you’re golden.

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Re: Epoxy over well sanded Gelcoat?

Post by OneWayTraffic »

Isn't the Gelcoat more brittle than glass? If this area was under some bending stress that might be an issue.

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Re: Epoxy over well sanded Gelcoat?

Post by fallguy1000 »

Keep sanding. 90% glass is good...epoxy bonds best to about 40 grit
My boat build is here -------->

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Re: Epoxy over well sanded Gelcoat?

Post by APLJaK »

Thanks

I'll put a bit more "tooth" into the surface with 40g and then proceed.

I appreciate the advice

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wpstarling
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Re: Epoxy over well sanded Gelcoat?

Post by wpstarling »

I've done the same and didn't have issues with it sticking but there's a lot of variables that could make it different, age, type of gelcoat, how the surface was prepared to begin with, etc. Also depends on how good of a finish you want I'd think.
Boats restored: 1973 Glastron CV16, 1990 Proline 17 CC, 1993 Bass Boat
Boats built: custom 15ft flat bottom skiff, Soon-to-be-built TX18 (originally dborecky's build)

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APLJaK
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Re: Epoxy over well sanded Gelcoat?

Post by APLJaK »

Glassed the bottom of the very old skiff including closing off the two giant holes in the keel yesterday. No issues.

The glass came out beautifully. I have lots of experience glassing on new glass/epoxy while building my CX19, but repairing an old boat, especially a polyester resin boat, was still new to me. I appreciate the advice!

Lucky, this is a small skiff that is used simply to transit from shore to an anchor point in the lake. Doesn't have to be beautiful, but I am very happy with how it turned out.

Might use up the last of my graphite and give it a new bottom coat while its on the sawhorses.

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