Epoxy + Varnish Method for 2-sides?

[Djarraluda]

Cabo,
Probably laid it on too thick, or not adequate hardener. Epoxy is very particular about the mix and temp.
Worst thing is when you get the amine bloom, it all goes cloudy and you exclaim - loudly!

I am currently trying an alternative varnish over the epoxy on my boom crutch. 2 months in Sydney sunshine so far. Previously I have used normal varnish over 2 pack, clear polyurethane and it works well, I am just experimenting.

[Lokiyawl]

I have Epifane base coats on my Loki that have endured the tropics and have survived since 2000,and still look good. Epoxy has very poor UV characteristics and will go cloudy and fail within a few years unless you put UV covers over everything so coated. Don't use epoxy under varnish if it will be out in the sun. James

Originally Posted by Roy M

I subscribe to the belief that water can make its way into anything. Therefore, if I don't want that possibility, I seal everything first with epoxy. Then I apply whatever I want for the intended purpose. For example, I just wooded down my handrails and hatch coamings for cosmetic reasons. I then sealed all the accessible surfaces with West System, using the 207 Special Hardener, for its added UV protection qualities. Several coats later, everything looks like it has been coated with about ten coats of perfect varnish. But that's just the base coat. Now, I am about to apply 2-3 coats of clear linear polyurethane finish to the sanded epoxy base. After several months of exposure (and pridefully showing off the beautiful teak finish) I will coat the clear LPU with the same paint I use for my primary hull color. This is because I am preparing to sail over the horizon to some very sunny places. When I am done wandering, should I be insane enough to want to show off the teak (which I would do if I were going to sell the boat) I merely have to sand off the outer layer of white, getting to the clear, then apply one coat of shine. I've done this for other cruising boats heading off to Mexico and beyond. Now it's my turn.

[Roy M]

Sorry, Loki, you are making a statement based on few facts. Yes, it is a fact that epoxy resin polymers don't survive ultraviolet light. BUT, epoxy resins with specific hardeners are more likely to survive longer than unprotected epoxies. THEN, if the stabilized epoxy base is further protected by a clear coating with additional UV blockers, the epoxy holds up better. NOTICE, PLEASE, that i am not saying it lasts forever, merely that it survives longer than varnishes with UV inhibitors. NOTICE, FURTHER that I clarify that only a UV opaque coating provides the protection needed to survive for a couple years. There is no coating yet formulated that lasts forever. All we can ask for, at the present, is something that reduces the frequency of wooding down and recoating for another few years. So far, only the linear polyurethanes appear to meet the requirements for enduring the damaging rays of ultraviolet radiation from the sun, especially the tropical sun. Unless you have better information........

[Mithril Bham]

Such a big topic. So many differing opinions in this area. I use two coats of epoxy (sanding between coats) and five coats of varnish. Have used many other methods but this is best for me. Don't know why the above epoxy dripped. Coating is always time and temperature sensitive. Seems like he probably didn't mix the right amount of accelerator and resin but who knows.

[LakeSuperior]

The biggest problem with epoxy undercoats is getting back to bare wood after the varnish overcoats have failed and the epoxy is compromised by the UV (which it will eventually.) In the long haul I have found it best to gut it out with varnishes having the highest level of UV additives.


If you can stand it Sikkens holds up pretty good compared with varnish and can be repaired and maintained nicely.

[Lokiyawl]

My information is based on 40+ years of being in the business and seeing what works. I have tried a few different epoxy coatings, including the West and the Smith's, with linear poly over… both went cloudy after 3-4 years. I have also watched others use various epoxies under clear coatings with similar results. While there are certainly a lot of different ways of doing things and it often happens that more than one will work, the combination of epoxy and varnish (linear poly or otherwise) for exterior woodwork is a bad idea..I have yet to see the system survive near as long as properly applied and maintained varnish. The water that blows the varnish off btw in most cases comes from the unsealed under surface of the woodwork, rather than from the top so applying a complete sealing coat that prevents any drying through the outer surface actually tends to accelerate the finish failure at the joints. Imagine wet wood coated in something that is a complete seal with the sun beating down on it..the vapour pressure of the water trying to get back out is significant. Sealing wood, even teak in such a manner can lead to rot problems. If you have a cold moulded boat and want to varnish the hull, then I guess you have to use the epoxy but be willing to strip it back to wood when the epoxy begins to cloud up. I do agree with what you said about no finish lasting forever, goes double for the clear ones!

James

Originally Posted by Roy M

Sorry, Loki, you are making a statement based on few facts. Yes, it is a fact that epoxy resin polymers don't survive ultraviolet light. BUT, epoxy resins with specific hardeners are more likely to survive longer than unprotected epoxies. THEN, if the stabilized epoxy base is further protected by a clear coating with additional UV blockers, the epoxy holds up better. NOTICE, PLEASE, that i am not saying it lasts forever, merely that it survives longer than varnishes with UV inhibitors. NOTICE, FURTHER that I clarify that only a UV opaque coating provides the protection needed to survive for a couple years. There is no coating yet formulated that lasts forever. All we can ask for, at the present, is something that reduces the frequency of wooding down and recoating for another few years. So far, only the linear polyurethanes appear to meet the requirements for enduring the damaging rays of ultraviolet radiation from the sun, especially the tropical sun. Unless you have better information........

[IdoraKeeper]

Where ever you are you will have different problems there. In the PNW generally we have a water problem as identified by Loki. We don't get the extreme cold but its cold enough for long enough to cause freeze cracks, the rain and pollen and mildew get in there and you get the typical discolorations....If you keep wooding down totally you never get to sail and you lose millage.
My worst UV problems are on my Penguino stitch and glue kyaks..epoxy flaking in the summer sun. Can't use varnish cause they get dragged up on the rocky beaches around here.
I guess you just have to keep at it cause nothing will last more than two years.

[cabo_sailor]

I don't know for sure why I got the drips. It seems that just before the epoxy kicked it became more liquid.

As to the ratio of resin to hardener, I used the West micro pumps.

Rich


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[Lokiyawl]

Room temperature cure epoxies such as West can be easily removed from wood by using a heat gun and a scrapper. The epoxy softens at a quite low temperature, perhaps 160F or so is plenty so no need to burn the wood. Probably a really good idea to wear a carbon mask during this process.

The key ironically to reducing the upkeep of varnish is to do tend to it often. It is quite easy to scuff sand and apply two fresh up coats but a huge job to strip and rebuild from bare. I found that in Florida that for surfaces flat to the sun, that 3-4 months was about the limit in the summer for Epifane. I found that a year was ok on spars that are vertical. If you wait until you have any crazing, the base coats are pretty much shot..you have to catch it while it still looks good. The linear polys that I have used can sometimes go up to 2 years without touching them but they all seem to go cloudy after about 4-5 years. The Epifane base coats can last a lot longer I have found if the surface coats are renewed often enough. Best of luck. James

Originally Posted by LakeSuperior

The biggest problem with epoxy undercoats is getting back to bare wood after the varnish overcoats have failed and the epoxy is compromised by the UV (which it will eventually.) In the long haul I have found it best to gut it out with varnishes having the highest level of UV additives.


If you can stand it Sikkens holds up pretty good compared with varnish and can be repaired and maintained nicely.