Long term issues, varnish over epoxy

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Antler24
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Long term issues, varnish over epoxy

Post by Antler24 »

Are there any long term issues varnishing over epoxy? Im apart of a couple wooden boat groups on facebook and a couple of times folks have had the idea that epoxy under varnish will (not can, it WILL) fail as a coating and turn yellow, hazy, and even delaminate from decks. They are convinced that its not just possible for epoxy to fail as a coating, its simply a matter of time before the epoxy fails, then it needs to be stripped to bare wood. They recommend instead to use a pettit sealer under varnish, and then an acrylic on top of the varnish.


Of course this goes against everything I've learned on this forum, and Im very weary about it. I didnt give it much thought after I saw these posts a few months ago but recently I saw another member posting the same things and it got me wondering. If an adequate amount of UV protection is used and maintained, how can the epoxy degrade over time?


Any finished boats on this forum seen any long term issues with epoxy failures under varnish?

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Roberta
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Re: Long term issues, varnish over epoxy

Post by Roberta »

I have never been a real fan of epoxy under a varnished finish. I think the reason epoxy fails under varnish is due to a lack of UV inhibitors that protect the varnish and everything below it. Varnish UV inhibitors float to the top of the product as they are applied. As the varnish "wears out" with age, it needs to be refreshed. Refreshment intervals are based on age, time in the sun, and how the boat is stored. The more protected the boat is, the longer between the time it will need to be sanded and several to many new coats applied.

On the Torpedo, I went a different route. I stained and sealed with epoxy resin. Then the finish was done using two part Poly-urethane paints. The Torpedo is entering it's 7th boating season with very little noticeable degradation in the finish. Two part Poly-urethane paints have UV inhibitors throughout the coating and do not wear off and are not sanded off when recoating.

The Zip I built had 17 coats of Epifanes varnish and has held up well. I refinished that boat in January of 2013. I don't think the new owner has had to refinish that boat and it still looked great last year. It was stained, sealed with Pettit sealer, and then the vanish was applied. No epoxy was used.

Here are some pictures of the Zip after refinishing, of the Torpedo during completion, and one taken a few days ago during some cleaning of caulk lines.

Roberta :D
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redo done 004.JPG
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

Hercdrvr
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Re: Long term issues, varnish over epoxy

Post by Hercdrvr »

I dont encapsulate the decking because varnish alone protects the wood from water and sanding epoxy is a pain. It’s all about the level of exposure. There are plenty of parts l leave bare wood, like the underside of the bow decking. If it gets sun or water under there, it’s a bad day. From the keel out to the chine is another story, I glob the epoxy on.
The most extreme exposure on my boat is the Ash wood soul. It gets lots of water and sun and foot traffic. It needs sanding and varnishing every other year. Probably why most boats have carpet on the soul.
When I started building boats and discovered epoxy I thought it was the answer for everything and I over used it. It has its function but wood in direct sunlight ain’t it unless it’s covered in paint.
My 2 cents,
Matt B
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steveh41
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Re: Long term issues, varnish over epoxy

Post by steveh41 »

Here's a quote from the System 3 "Clear finishing over wood" brochure:

"System Three Marine Spar Varnish™, a high gloss/silky satin, high-solids, "oil-base" finish, is designed for marine and exterior wood surfaces. Our Spar Varnish is a polyurethane formulation, and contains ultraviolet light absorbers which will keep wood looking beautiful even with constant exposure to sunlight. It was formulated specifically to cure properly over System Three epoxy resin products."

My 2 cents...
The longest journey begins with a single step… then repeat as necessary!

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Roberta
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Re: Long term issues, varnish over epoxy

Post by Roberta »

Their varnish is polyurethane. Always good to stick with a manufacturer family or tried and true methods.

Roberta :D
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

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kens
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Re: Long term issues, varnish over epoxy

Post by kens »

within today's modern age of 2-part paints, 2-part epoxies, urethanes, polyurethanes, why on this green earth would you want any old school 'varnish'??

Albeit, I did use satin varnish on the stripper canoe, and 1 reason only.......I did it on the cheap because it gonna get scratched up with crab traps.

Those same people talk about what such a FINE finish they put on their boat, and they got all the finest modern products available to them, then they talk about 'varnish'.
Polyurethanes are compatable with epoxy, this has been proven many times over.
The only reason to use varnish is to be cheap, it does not last longer, does not UV protect any better, does not look any better than modern finishes.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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Bill Edmundson
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Re: Long term issues, varnish over epoxy

Post by Bill Edmundson »

I agree with Ken! I do have an allergy to some of the solvents used. :(

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

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Roberta
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Re: Long term issues, varnish over epoxy

Post by Roberta »

I would not call using varnish "being cheap". It's a personal preference that can be more expensive and more work. And there are differences in look and feel.

Roberta :?
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

Antler24
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Re: Long term issues, varnish over epoxy

Post by Antler24 »

I just wanted to bring up the question to get some other opinions. I've long decided that Ill be using WR-LPU on my build simply because of the lack of solvents. The extra UV protection and durability are icing on the cake.

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Roberta
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Re: Long term issues, varnish over epoxy

Post by Roberta »

WR LPU is a very good product. I originally used it on the Zip. It remains on the bottom, but I did do a redo on the Brite finish with Epifanes varnish.

It is best applied when humidity is high to prevent early flashing. Use thin coats of fairly thinned product. Do not over work it and try to fix mistakes. Let it dry and sand mistakes out between coats. You can apply several coats in a day. It dries very quickly. If you coat too heavily, you'll be wiping it off the floor and creating lovely curtains.

Do any sanding prior to the paint curing. Once it cures, it is extremely hard and difficult to sand. Some people omit the crosslinker until the last coat or two so it can be sanded at a later date. The clear is very clear and will not darken any wood or stain. Follow System Three directions and recommendations.

Roberta :D
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

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