FINISHING WITH GEL COAT OVER EPOXI

TUNICAO · Post by **TUNICAO** » May 18th, '09, 21:31

Hi,

Does anyone happen to know something or someone had already done this type of finnishing? Gel coat over epoxi primer or barrier?

Thank you and always good winds,

Tunicao :?:

Buju · Post by **Buju** » May 18th, '09, 21:41

Epoxy bonds well to polyester. Polyester does not bond well to epoxy... generally speaking.

CaptPatrick · Post by **CaptPatrick** » May 18th, '09, 21:56

Tunicao,

Won't work... Gelcoat is a polyester resin and will not bond to epoxy. There is a material that can act as a tie coat and that's Duratec Grey Surfacing Primer.

Duratec primer has a short shelf life and must be used very soon after you purchase it. Make sure that your supplier has fresh material before shipping. Make them shake mix it and visually check to assure a complete mix. Don't order it prior to being ready to apply it.

Did I mention that it'll go bad in the can muy pronto?

It is, however, the only way that you'll get gelcoat to stick to epoxy.

Br,

Patrick

TUNICAO · Post by **TUNICAO** » May 19th, '09, 10:07

Buju and CaptPatrick,

Thank you for the information, actually I already new this rule of thumb that Buju remembered me. But I've tried using (as a test) styrene to clean the epoxi surface and "painting" with gel coat before the styrene had fully dried. After the gel coat has cured (I used PVA as air block) I can not take the gel coat out of the epoxi surface not even with the use of a blade. But as Buju well said, polyester does not stick to epoxi. But after using styrene as a cleaner and sort of primer I start think it may be a solotion. and also reading the Duratec composition, I shaw that Styrene is on it beside Xylene and MEK. I'll take a photo of my test to sent to the group.
Still want to know if some body had my experience
Once again thank to Buju and Capt.
Tunicao

Buju · Post by **Buju** » May 19th, '09, 11:17

I don't know Tunicao...
It seems like a lot of trouble to go thru, with no real benefits.

Unless the gelcoat is initially applied in the mold, I don't beleive there
is any superiority over the multitude of quality marine polyurethanes.
Why not just apply a few coats of paint over the faired epoxy primer
and be done with it?

CaptPatrick · Post by **CaptPatrick** » May 19th, '09, 11:37

I can not take the gel coat out of the epoxi surface not even with the use of a blade.

Don't be fooled by a green test... While it may seem that you have good adhesion of the gelcoat over the epoxy at this point. But as both the gelcoat and epoxy age and shrink the bond will likely break down without the Duratec polyester primer to act as a tie coat.

TUNICAO · Post by **TUNICAO** » May 19th, '09, 12:21

Hi Capt.,

Thank you, I'll try to find Duratec here in Brazil, otherwise I'll do it with PU.
Always good winds,

Antonio

Chiles · Post by **Chiles** » May 21st, '09, 14:42

I used Duratec when I did my repairs. So far, two years later the gel coat is still holding.

That bad news is that I had to buy a gallon of the stuff and and only needed a pint. I had to dispose of a lot of Duratec.

-Chiles

TUNICAO · Post by **TUNICAO** » May 21st, '09, 15:48

Hi Chiles,

Thank you for the information, I'm looking for Duratec here in Brazil. It's good to know that some one already had a good record on my subject.

Always good winds,

Antonio

TUNICAO · Post by **TUNICAO** » May 22nd, '09, 15:48

Hi,

I found Duratec here in Brazil, got very good information from RD Ltd. company that imports Duratec to Brazi and also from Reichhold the Gel Coat (NGA 20000S Refinishing) both told me that using Duratec and them the Gel Coat it will turn out like new. They all gave me very good information about what should I do and take care. If any one wants the holl information let me know and I'll send an email.

Thank you for the help and always good winds for all. Hey Buju! A V6 sometimes ... but thank you!

Antonio

CaptPatrick · Post by **CaptPatrick** » May 22nd, '09, 17:53

Antonio,

Glad you found it in your area. Remember what I said about the short shelf life and have the Duratec people shake mix and open the can to check for a complete mix before shipping it to you. And don't order it until you're ready to use it.

Br,

Patrick

TUNICAO · Post by **TUNICAO** » May 22nd, '09, 18:32

Hi Capt.

I would never forget you info about Duratec, anyway thank you for reinforcing it.

Do you know about Ultrasonic Antifouling? I got one from England. See the sit http://www.ultrasonic-antifouling.com . I'll try to use on my boat, if it works OK, we let you know.

Always good winds and if it shut down, turn on your V6.

Antonio (tunicao)

bertram31.com