Well, after some testing on all the components it turns out to be the spar varnish. It sets up with a very sticky, rubbery feel to it and not a hard finish. I bought some Armor Coat spar varnish, a Canadian product and it works as it should. Problem in Canada is we've banned a lot of the nasty chemicals and spar varnish is hard to find. What's on the shelf may have been there for a while.

Nothing is foolproof to a sufficiently talented fool.