epoxy varnish compatibility problem

[DudKC]

Thanks for all the advice. After I sand my final epoxy coats, would you just use a tack cloth and wipe it off before applying the spar varnish? Or would you wipe it down with acetone after tacking it off?

[Chuckles]

Chuckles,
I still suspect the varnish your using as being the problem.....
IMO/ epoxy does need protection from UV, but using consumer grade "spar urethane" varnish is not the way. For UV protection you want a true marine grade spar varnish. Costs more per quart, but less per year of service. The four tried and true varnishes that qualify are: Epifanes Gloss, Interlux Schooner, Pettit Captain's and Flagship. Consumer grade single-part urethane resin is more susceptible to damage from UV than the traditional resin's. The spar urethane adds the UV protective additives to get back to "acceptable", while the marine grade uses the additives to increase protection and extend longevity. You won't find the real marine finishes at ordinary paint stores. Here's a good source: http://www.jamestowndistributors.com/userportal/search_subCategory.do?categoryName=Varnish&category=36&refine=1&page=GRID

Larry,

After seeing how it performed I think you might be right on the varnish being the problem.

I did look at the high end marine varnishes but the price tag is a real shocker. Now generally I am a firm believer in "you get what you pay for" but my thinking is - do we really need to go full schooner for a teardrop that will be exposed to the elements three or four weeks on a good year and garaged in the interim? is the cost of the good stuff worth it? and of course they all say you need their proprietary thinners and surface prep mixes.

After reading the product descriptions I also had a question about the touted wood penetrating ability of the superior spar varnishes... with an epoxy coating there will be no opportunity for wood penetration. Its just a UV protecting film on top. I wonder of this is a source of the problem with the varnish I used? Does it cure more slowly if it has no opportunity to penetrate the wood?

Just thinking... which I have found is the source of most of my problems