Help! Varnish over Epoxy

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Jason Mayer Jason Mayer
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Help! Varnish over Epoxy

Hi everyone,

I am leaving a few nice pieces of natural grain exposed in my new build.  I put a coat of West System 105/206 epoxy to seal the timber, let it cure for a week, sanded and wiped it down with water, then put a coat of varnish over it.

After 3 days some areas of the varnish are very slightly tacky.  Summer is over and the weather is cool (for us) like 16 degrees C at night and a bit overcast and showery but the boat is indoors.

Is this a compatibility issue?  Or to be expected when the temperature is low the humidity is high?

Jason
Paul H (admin) Paul H (admin)
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Re: Help! Varnish over Epoxy

Tacky varnish implies the epoxy had not fully cured.
Patches of the dreaded amine blush may still exist.

The varnish will slowly harden. It took two weeks in the first boat I built! Something was wrong.

My theory is that epoxy on brightwork is not a good idea, It's too easy to trap moisture  and UV protection is not as good as solid paint

Others may have better solutions.

Paul
LASER41420 LASER41420
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Re: Help! Varnish over Epoxy

In reply to this post by Jason Mayer
Hi,
It could also be the humidity, cook it with a fan heater or hair dryer and see what happens.
Steve
Port-Na-Storm Port-Na-Storm
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Re: Help! Varnish over Epoxy

In reply to this post by Paul H (admin)
Well Jason, this is the place to come to be told you're doing it wrong, great innit?
The entire Gudgeon Brothers and West System ethos of encapsulation thrown out with the bath water by Paulie.
Who can tell what has happened, the only solution is to give it a few days more and if it's still not hard gently sand back until you get to solid ground.
Those of us shivering here in the coldest April in sixty years will tell you that 16 C is the perfect temperature for varnish and paint. You could be right about the Humidity though.
Cheers
Graham.


From: Paul H (admin) [via UK HBBR Forum] <[hidden email]>
Sent: Sunday, May 2, 2021 8:30:16 AM
To: Port-Na-Storm <[hidden email]>
Subject: Re: Help! Varnish over Epoxy
 
Tacky varnish implies the epoxy had not fully cured.
Patches of the dreaded amine blush may still exist.

The varnish will slowly harden. It took two weeks in the first boat I built! Something was wrong.

My theory is that epoxy on brightwork is not a good idea, It's too easy to trap moisture  and UV protection is not as good as solid paint

Others may have better solutions.

Paul


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Rob Blackburn Rob Blackburn
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Re: Help! Varnish over Epoxy

As someone who has buggered more things up than most, I go to the bright/hot/ light and leave it on the area all night and see what has happened...

Make sure it is a halogen one, not LED, not too close to the item to melt and soften things, but just so over 12 hours the area is left nice and warm.

Just a thought. You may have already tried this.



Jason Mayer Jason Mayer
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Re: Help! Varnish over Epoxy

Thanks folks.

I tried heating and even got it out under some sunny days this week but to no avail.  There is still a slight tack in some areas.

The varnish manufacturer got back to me and confirmed no compatibility issues with overcoating West System epoxy....unless.....I over dosed the hardener.  Given that it is only certain patches, which were certainly different batches of epoxy there could be something in this.  Although I measure out using syringes so I am pretty darn accurate.

Anyway his solution is to dry sand and wipe down with acetone and put on another coat.  We have some warm sunny days coming so that will be the plan.  He reckons it will be OK.

My thoughts are the high humidity might have been a factor too.

I think a certain cobber on this forum whose name starts with G might have warned me that he doesn't bother with all the fuss of epoxy sealing then overpainting.  Maybe I should have listened hey?  

Jason
Paul H (admin) Paul H (admin)
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Re: Help! Varnish over Epoxy

Jason,

I was once told you had to wait a few weeks for the epoxy to fully harden, when I had tacky varnish on a D4 dinghy.

Apparently the epoxy stops the varnish drying out.
 
Paul
Jason Mayer Jason Mayer
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Re: Help! Varnish over Epoxy

Hmm Ok well I am only just getting to week 2 after the last epoxy coat.  Maybe I will leave it alone for the time being and work on other things and give it another week.  We are about to get a period of dry and warm so if I just leave it outside a small miracle might happen.  Better than rushing into sanding tacky varnish which I can't imagine will be "fun".

I did some reading and Mr Google also has an entry that said something similar about not rushing varnish over the epoxy.

Thanks Paul!

Jason
Rob Blackburn Rob Blackburn
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Re: Help! Varnish over Epoxy

It is a funny thing that clear finish caper here in the great Southern Land. I have it on my Core Sound and what started as polyurethane clear by BoteCote, was great to start with then it started to peel off like sunburned skin off your nose as a kid. Would simply come away in big sheets.

So sanded that off and went to Feast Watson floor oil (with Polyurethane added) which we have on the hardwood floor here at home and on our benches in the kitchen. Four coats and it is marvelous, strong glossy look, seems to go on better than Deks Olje, no little bubbles.  Easy to recoat. Really deep gloss.

However, couple of weeks away in the hot sun on the way to Tasmania saw it all go funny. Sort of hazy and heat affected. (it was pushing 40 deg for a couple of days, hot as buggery)

Sanded that off after redoing it all twice, then went the marine varnish with UV protection in it. Lovely while in the shed and under a tarp but once again, hot sun does not help it.

So the point I am making is that I have spent more time fooling around with clear finishes than I have spent actually sailing the boat I suspect.

I am starting to think that white enamel oil based paint is the best varnish. Apply it with a Wagner hand held spray gun, about 4 coats, with 10% thinners and you are getting close down here in Oz.

The other option is to get some custom boat covers made to keep the elements off. I did that but the the thing that got to me was that the turbulence in the air in the boat as you drove along at 110km/hour made the cover rub on a few bits of the clear and was no different to sand paper. So 18 hour drive to Melbourne resulted in bare timber.

I know this sounds all very glum but just saying. I do love the look but really it is a torture at times.

At Horseshoe Bay

Allecat at Peel Island

I really admire your energy and work ethic. Love to see the videos of the boat in action soon.

Cheers

R





Jason Mayer Jason Mayer
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Re: Help! Varnish over Epoxy

Yes let's see how it all goes.  If it falls apart then the next time you see Kalliope she might be all blue inside!

News flash...!!!....by some miracle of nature, today I checked and three quarters of the varnish is now properly cured!!

Don't know how, don't know why, but I'll take it because it should mean that the other quarter is on its way to salvation too.

Jason Mayer Jason Mayer
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Re: Help! Varnish over Epoxy

Final update on this thread.  After 2 and a bit weeks the varnish cured.  There were a couple of small areas still very marginally tacky but I gave it a sand, wiped down with mineral turps (spirits) and gave it two more coats this weekend.  Both cured properly each night.  So I have finished the varnishing (2 coats epoxy, 3 coats UV rated marine varnish).  There really isn't much varnish on this boat and it really only takes a half hour to give it a sand and a coat so hopefully I can keep it in good nick each year.

So it could have been a few reasons why there were problems. Paul suggested epoxy should be left 3 weeks before varnishing to properly cure.  There was extreme humidity in the hours after applying.  The manufacturer thought there might have been a contamination issue (amine blush?).

Anway all's well that ends well.

Thanks for the inputs and ideas.

Jason