Hi Hank,

I guess I will be the spoiler here. Urethane is far and away superior to varnish. (I am talking two component urethanes and polyurethanes)

It is like comparing a model T to a 2000 Corvette. (urethane being the Corvette) There is no compatability problem between epoxy and urethane. In fact the better the substrate the better the bond. Urethane not curing would indicate a problem with the product (usually out dated) or a problem with the application.

Your new car has a urethane paint with a urethane clearcoat over top. Besides washing it, it requires nothing to keep it looking great for years. (Ten years is the life expectancy in an environment far harsher than your kayak will ever see)

There is no coating that gives a higher D.O.I. (Definition of Image) This is the measure of the reflective surface of the finish. Only water has a better D.O.I. and that is because as the solvents evaporate out of the finish it experiences Die Back which results in the texture known as orange peel. All solvent based finishes experience die back.

I have never seen a varnish have a finish anywhere near as glossy as a urethane. Plus, urethanes are crystal clear so the add no colouring to the project, but they can be dyed to produce some really wild effects.

(Or you can just disregard this as another urethane post by Ian)

Ian