Clear coat over epoxy = Bubble :s HELP!!

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Z_Wood
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Clear coat over epoxy = Bubble :s HELP!!

Post by Z_Wood » Sat May 05, 2012 8:18 am

Hello folks

I finished my rebel with 5 coats of epoxy then about 10 coats of good german quality automotive clear coat sanded and buffed polished etc etc.... after i towed the boat and it sat in the sun for a bit BAM 2 quarter sized circles like a bubble formed... seemed like its the clear coat not sticking to the epoxy... SO i went ahead and sanded the bubbles and the whole surrounding area to bare wood then epoxied and clear coated again.... Same thing happened in the SAME area.... big bubbles that after a while they decided to unite and form one big ass bubble.... whats join on? :(

Anyone experienced this before?

Can someone shed some light please?!

Thanx in advance

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jeffh
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Re: Clear coat over epoxy = Bubble :s HELP!!

Post by jeffh » Sat May 05, 2012 8:48 am

Z,
My boat is also clear coated with automotive clear. The painted parts of my boat are done with automotive paint. I did not have the problem you describe, but two of my four hatches had some small pin-head bubbles which I suspect is some sort of contaminant. I've lived with them for a year now. All I have to do is remove the hatches and the trim and have them re-coated. I can say that my boat was epoxied and it cured for a long time. It was DA sanded and then coated. The clear coating took a couple of weeks before it was sanded and polished.
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gdcarpenter
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Re: Clear coat over epoxy = Bubble :s HELP!!

Post by gdcarpenter » Sat May 05, 2012 3:42 pm

I feel your pain, but not sure I can give you an answer. Sounds like some local contamination in one area, but since you resanded down to bare wood that seem less likely. Perhaps use some type of sealer in that local area for the next go around. Some here recommend CPES sealer but I have no personal knowledge of that. Shellac is a good sealer but you would have to experiment or research you ensure that top coats would adhere, but if you epoxy over shellac you should be okay from what I understand.
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vupilot
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Re: Clear coat over epoxy = Bubble :s HELP!!

Post by vupilot » Sat May 05, 2012 4:01 pm

Sounds like contamination of some kind.
Also when coating with epoxy or clears like varnish its best to apply after the daily temperature has peaked and the temps are on the way back down otherwise you will like get smaller bubbles from the outgassing as the temperature climbs. Putting a finish in the sun while it cures will cause this also in my case it was thumbnail size and smaller but many of them all over so doesnt quite sound like your issue in this case.

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Roberta
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Re: Clear coat over epoxy = Bubble :s HELP!!

Post by Roberta » Sat May 05, 2012 4:56 pm

Did you let the epoxy fully cure for a couple of weeks before painting? It will gas out until fully hardened.

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Bill Edmundson
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Re: Clear coat over epoxy = Bubble :s HELP!!

Post by Bill Edmundson » Sun May 06, 2012 6:19 am

Did you make sure the epoxy was cleaned of any amine?

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Z_Wood
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Re: Clear coat over epoxy = Bubble :s HELP!!

Post by Z_Wood » Fri May 11, 2012 11:36 am

Hi guys and gals.... thanx for the replies!

Ok i am sure the last coat of epoxy was cleaned properly after its been sanded and before i sprayed on my clear coat.

The epoxy was left to cure but not for 2 weeks.. West system said few days is all it needs.

Now the bubbles are forming on the clear coat where its not bonding to the epoxy... and theyr not like pin holes... their big bubbles.

what boggles my mind is why would they form again in the same spot after iv sanded the whole area back to bare wood?!!

I called west system and told them the problem and they were surprised and didn't have an answer for me... said they'll discuss it and get back to me.

Ill take a pic and post it in a little bit.

Im really annoyed with this :'(

red
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Re: Clear coat over epoxy = Bubble :s HELP!!

Post by red » Fri May 11, 2012 8:20 pm

z wood what clear are you useing is it automotive poly ,enamel, laquer or acrylic?

Z_Wood
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Re: Clear coat over epoxy = Bubble :s HELP!!

Post by Z_Wood » Fri Jun 01, 2012 12:55 pm

Hey fellaz... sorry was gone for a while. Heres some pics of the bubbles I'm talking about. The stuff i used was automotive 2 part acrylic.

The other thing that also happened a lil later was i started getting hair line cracks where the joints are between the mahogany and maple planks :( could those cracks be just the top coat or can it be all the way down to the epoxy? I also had one of the mahogany veneers split! whats going on with my boat???

Could it be the heat or the direct sunlight? Its pretty damn hottt here.

I contacted west system and told them bout the bubble problem and they basically had no answer and said they never hear of a situation like this especially that i sanded the whole area back to bare wood and did the epoxy and clear coat all over again.

My plan B is to sand the whole clear coat off and use a different product.

I wish to resolve this problem.

Zane...
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Bill Edmundson
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Re: Clear coat over epoxy = Bubble :s HELP!!

Post by Bill Edmundson » Fri Jun 01, 2012 1:05 pm

Zane

I used a 2-part PU Interlux clearcoat. I think the heat may be the source of the cracking and checking.

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Bill CNC
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Re: Clear coat over epoxy = Bubble :s HELP!!

Post by Bill CNC » Sun Jun 10, 2012 8:53 pm

Has the wood been exposed to moisture? I have seen spots in west systems that looked like snow flakes like you have. A club mate confirmed it was from wood with a high moisture %. He tested his hunch by laminating to samples from different wood sources he had. One was seasoned and the other was the piece in question.

Try doing a test using the same finishing steps on a different piece of wood, ... start to finish.

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Feckless
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Re: Clear coat over epoxy = Bubble :s HELP!!

Post by Feckless » Tue Jun 12, 2012 7:34 am

Going to agree with Bill, that could be moisture. May also explain the cracking and checking with high temp changes.
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Bill CNC
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Re: Clear coat over epoxy = Bubble :s HELP!!

Post by Bill CNC » Tue Jun 12, 2012 1:47 pm

Feckless wrote:Going to agree with Bill, that could be moisture. May also explain the cracking and checking with high temp changes.
Yup, ... I think when he puts it in the sun, it's trying to steam out.

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