Gelcoat on Expoy

[sailorboy1]

I had a small spot on my cabin that was cracked and soft. The good news is that when I ground it out it was just a void between the fiberglass and the gelcoat and not a core problem. So I filled in the spot with thickened expoy with the plan to cover with some gelcoat.

So today while doing some other stuff I got the gelcoat kit out and being me read the directions. Right in the directions it says that the gelcoat sticks poorly to expoy. So what gives? Is this true and if so what do you coat the expoy with prior?

Or is it BS and the gelcoat will stick to the expoy without issue.

I'm talking about a 1" square spot.

[rhr1956]

My understanding is epoxy will stick to polyester but not the reverse. Gel coat is polyester.

[psneeld]

Originally Posted by rhr1956

My understanding is epoxy will stick to polyester but not the reverse. Gel coat is polyester.

Same rule of thumb I always heard...WEST guys say you can gel coat to epoxy...go to their website and read up on how they claim it can be done...

[capttman]

Originally Posted by rhr1956

My understanding is epoxy will stick to polyester but not the reverse. Gel coat is polyester.

That is true.. should use polyester or vinyl-ester on your repairs

[Jamel]

Originally Posted by Don Lucas

I had a small spot on my cabin that was cracked and soft. The good news is that when I ground it out it was just a void between the fiberglass and the gelcoat and not a core problem. So I filled in the spot with thickened expoy with the plan to cover with some gelcoat.

So today while doing some other stuff I got the gelcoat kit out and being me read the directions. Right in the directions it says that the gelcoat sticks poorly to expoy. So what gives? Is this true and if so what do you coat the expoy with prior?

Or is it BS and the gelcoat will stick to the expoy without issue.

I'm talking about a 1" square spot.

Sounds to me you are doing a cosmetic repair on a very small area. Now the apoxy is in place already, salvage the situation by sanding the spot to provide a "key" so that the gelcoat will stick. Keep in mind for future reference, gelcoat on apoxy not good particularly in structural situations.

[sailorboy1]

I'm talking purely a cosmetic thing here. All I want to do is blend what right now looks like a flesh wound and keep the sun from beating it.

[Celestialsailor]

Ron Moore of Moore sailboats helped me with that problem one time. He told me to put vinylester resin over the epoxy and then the polyester...worked!

[ozskip]

If you do a search on this in the archives Gordmay had an article on this subjuct titled, Will gelcoat adhere to epoxy. Was very interesting.
Greg

[capngeo]

On small cosmetic spots, it isn't a big issue. Large areas will pop eventually. As mentioned above, sand it to rough the substrate, then gel, feathering the edge to the old gel.

[DeepFrz]

West Systems says it should adhere very well. Of course you have to wash off any amine blush and then rough up the epoxy with sandpaper after removing the amine blush.

It is not often used as a post-production finish coating, but it can be applied over epoxy and is useful in some repair situations. Refer to Fiberglass Boat Repair and Maintenance, published by Gougeon Brothers, for detailed information on patching gelcoat over an epoxy repair.

[minaret]

I've tried and it won't stick. Amine in the epoxy keeps the gel from curing properly.545 works for a tie coat. So does vinylester resin.

[Overlord]

It will work perfectly.We do it every day.Just roughen the epoxy area with a piece of production paper , wipe with acetone and apply gelcoat.
123 and bob's your uncle !

[motion30]

I also have done it with no problemm but I dont know uncle bob

[donradcliffe]

Mine looked fine for 5 years, but the gelcoat is now starting to crack and pop off.

[GordMay]

"Polyester over epoxy" ~ by Jeff Wright
“... gelcoat applied over properly prepared WEST SYSTEM epoxy has a great track record ...”
See ➥ WEST SYSTEM | Projects | Fiberglass Boat Repair and Restoration - Polyester over epoxy
Or ➥ http://www.westsystem.com/ss/assets/...2Polyester.pdf

Originally Posted by DeepFrz

West Systems says it should adhere very well. Of course you have to wash off any amine blush and then rough up the epoxy with sandpaper after removing the amine blush.

Right.
A simple wash with clear water removes amine blush. No soap, no solvents. Then sand that washed surface with 80 grit paper, to provide the gelcoat with sufficient key so it won't run. Be sure to use non-air inhibited gelcoat that has a paraffin wax added.

Originally Posted by ozskip

If you do a search on this in the archives Gordmay had an article on this subjuct titled, Will gelcoat adhere to epoxy. Was very interesting.
Greg

Here ➥ http://www.cruisersforum.com/forums/...poxy-5794.html