I am using System Three epoxy and the Epoxy Book that came with it states that the epoxy BEGINS to break down after six months of continuous exposure to intense UV rays. This may or may not be the case with another company's epoxy.

Color changes to the underlying wood will take place within hours of UV exposure however. The only problem with that is if you have hatch straps etc. that cover part of the wood, you will get "tan lines". Ricci