: West systems epoxy. The 207 hardner Has UV built in. I think that
: will be the best for durability... kirk

Well, that's what I read for the 207: "An ultraviolet inhibitor in 207 helps provide a beautiful, long lasting finish when used with quality UV filtering varnish". Notice the " ... when used with quality UV filtering varnish"? Looks like the built-in is not enough. And varnishing seems to require something like 7 coats with sanding in-between (based on some JD videos I looked for marine varnish on wood).

Does anyone know of a specific UV inhibitor additive that I can mix with my epoxy?

May be I'm just overthinking it. My paddle will not see that much sun exposure to probably matter, I don't care about its color - only about the strength of the material. So I might just spray on a few coats of the automotive clear coat that I already have and be done with it... I highlly doubt paddle manufacturers of composite paddles apply coats and coats of finishes - I suspect they only use UV-resistant epoxy/hardener in the mold...