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Old 13-02-2016, 11:47   #1
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Gelcoat can be successfully applied over Epoxy repairs

Here’s the test to prove it.

In the past, most pro’s would tell you that you have to paint over an epoxy repair.


Gelcoat is only for covering a Polyester repairs. It not true.


Gelcoat can be used over Polyester or Epoxy.


https://youtu.be/kHAbyglpp3M

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Old 13-02-2016, 12:15   #2
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Re: Gelcoat can be successfully applied over Epoxy repairs

My opinion, Gelcoat over epoxy suck, and I see few vids from this guy in youtube, is quite funy, amine blush, that's it... all my experiments with gel over epoxy are good at first glance , after few months or even just few months exposed to the elements , the patch fail , I don't know why but definitely no matter how good and carefully the prep is done the adhesion fail, and my guess is amine blush no matter how well you sand or clean the epoxy job,, just my 2 cents...
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Old 13-02-2016, 12:46   #3
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Re: Gelcoat can be successfully applied over Epoxy repairs

I plugged some holes from when I replaced a windlass with epoxy. Later I was having gelcoat work done and asked the guy to gelcoat over the plugs. The gelcoat failed after a few months.


I'm going to stick with the thought that it doesn't work based on that experience.
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Old 13-02-2016, 13:00   #4
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Re: Gelcoat can be successfully applied over Epoxy repairs

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Originally Posted by neilpride View Post
My opinion, Gelcoat over epoxy suck, and I see few vids from this guy in youtube, is quite funy, amine blush, that's it... all my experiments with gel over epoxy are good at first glance , after few months or even just few months exposed to the elements , the patch fail , I don't know why but definitely no matter how good and carefully the prep is done the adhesion fail, and my guess is amine blush no matter how well you sand or clean the epoxy job,, just my 2 cents...


Yep. Most time I've seen given in a test was by WEST, and they did the adhesion test 9 weeks after spraying gel. Not enough time. IME, failure usually occurs after year one but before year two. No gel over epoxy without a tie coat.


I believe this occurs because very small amounts of amine blush continue long after curing. This breaks down the poly at the bond interface. There is no such thing as a blush free polyamide-if it's a true polyamide epoxy, it blushes. Don't believe the hype!


I have yet to see a manufacturer suggest it is OK to put a structural poly layup over epoxy. If it's not okay to bond poly glass work to epoxy, why would it be ok to bond gel to it?
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Old 13-02-2016, 15:55   #5
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Re: Gelcoat can be successfully applied over Epoxy repairs

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No gel over epoxy without a tie coat.
Minaret, w hat tie coat do you use?

im
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Old 13-02-2016, 17:13   #6
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Re: Gelcoat can be successfully applied over Epoxy repairs

Where would you even want to do this? Underwater? West/hi density e2000. Topsides? West/low density, micro balloons or ultralite, epoxy primer (545) Awlgrip or competitor equivalents. If a small gelcoat (small chip in precious non-skid pattern) repair is absolutely necessary, use polyester resin , it will stick adequately if prepped right...not as tenacious as epoxy bond, then match gelcoat...no mix and match for me...



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Old 13-02-2016, 17:16   #7
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Re: Gelcoat can be successfully applied over Epoxy repairs

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Minaret, w hat tie coat do you use?

im
That extra space made me look twice! I first read that as an enquiry about his dress sense
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Old 13-02-2016, 17:42   #8
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Re: Gelcoat can be successfully applied over Epoxy repairs

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That extra space made me look twice! I first read that as an enquiry about his dress sense
OOOpsss! Bloody keyboard...

Good catch, Stu!

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Old 13-02-2016, 22:17   #9
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Re: Gelcoat can be successfully applied over Epoxy repairs

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Minaret, w hat tie coat do you use?

im



545.



Not really a normal hat, tie and coat guy. Unless you count fullface respirator for hat, forced air line for tie, and a Tyvek for coat!
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Old 14-02-2016, 01:32   #10
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Re: Gelcoat can be successfully applied over Epoxy repairs

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545.



Not really a normal hat, tie and coat guy. Unless you count fullface respirator for hat, forced air line for tie, and a Tyvek for coat!
Works for me!
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Old 14-02-2016, 01:46   #11
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Re: Gelcoat can be successfully applied over Epoxy repairs

What is 545?


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Old 14-02-2016, 02:01   #12
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Re: Gelcoat can be successfully applied over Epoxy repairs

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What is 545?


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http://www.awlgrip.com/products/prim...xy-primer.aspx
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Old 14-02-2016, 11:37   #13
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Re: Gelcoat can be successfully applied over Epoxy repairs

How about: gelcoat in female mold, 3/4oz csm polyester (waxed) peelply'd, wait thirty days , Then epoxy/ balsa layup.

Did it about five years ago, but just been launched-oh how I do not want to go back there.
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Old 14-02-2016, 11:40   #14
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Re: Gelcoat can be successfully applied over Epoxy repairs

Hi,
Gliders are made with epoxy only, and most often covered with gel coat. However, when repairing, you have to use the resin and gelcoat from the builder, or approved by the builder.
Never seen any problem of adherence of the gelcoat with the resin. On the other hand, glider's gelcoat must be refit every 15 years, the surface becoming damaged by small the larger cracks. Maybe not the same gelcoat !
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Old 14-02-2016, 12:44   #15
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Re: Gelcoat can be successfully applied over Epoxy repairs

Quote:
Originally Posted by lateral View Post
How about: gelcoat in female mold, 3/4oz csm polyester (waxed) peelply'd, wait thirty days , Then epoxy/ balsa layup.

Did it about five years ago, but just been launched-oh how I do not want to go back there.



That's epoxy on poly, should be golden.
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