: I epoxied my Great Auk 5 years ago with West 105 & 207 slow
: hardener with UV protection.
: It's been outside ever since. There may be a little clouding, but
: not much.
: Basically, whatever is advisable is advisable, but.....you can get
: away with a lot for quite a while--at least five years.

: I did varnish it for about a year. The varnish, highly recommended
: hard marine stuff, was still so much softer than the epoxy it
: quickly got scratched, scraped, messed up. I sanded it off and
: gave it a coating of epoxy about a year ago.

: Long chain polymers like epoxy are essentially long molecules
: intertwined. (mono-filament fishing line is essentially a single
: continuous molecule).
: UV light photons knock out electrons weakening the bonds between
: the polymers and the bonds in the polymer chains. Think of that
: cheap bucket from the 99 cent store that ripped and fractured
: after sitting outside for a year. There's usually a significant
: difference between a plastic part on your car, and that cheap
: bucket.

: UV inhibitors absorb or lower the energy of the photons hitting the
: surface. Varnish, I'm guessing is a sacrificial surface. (I
: tried to check this out on Wikipedia and the Google, and didn't
: find the basic explanation that explains it more clearly. )

: What I should be thinking about is, the damage is cumulative, and
: the epoxy continually weakens and becomes more brittle even if I
: don't see anything visually. What's not so bad this year, might
: be horrible next year. Think of the accelerating effect of epoxy
: setting up in reverse. Everything's fine, everything's fine,
: everything's OK, yech

: I'm guessing what happened to Jay's paddle is less a UV effect than
: a thin seal coat wearing away from use. This is probably an
: ideal situation, making it easy to sand the surface and re-coat.

: Will

Btw, for an easy and fast varnish job at a reasonable price I like either Z-spar's Captain's varnish or Pettit's Easy-poxy varnish, the latter will give great results in the minimum number of coats and is very hard.

Bill H.