the front door on our house was replaced about 8 yrs ago with a Simpson glass over wood panel style in douglas fir. The door was stained and then finished with 4 coats of Minwax Spar varnish when installed. The entry is well protected from weather by a wide soffit, but gets a few hours of the late afternoon sun. The original finish held up well for about 5 yrs, at which time I had a painter look at it. He suggested sanding (not to bare wood) and re-coating with Waterlox Marine. From what I remember reading at the time, Waterlox Marine was ok over the Spar varnish so we went ahead with that plan. The Waterlox didn't hold up as well, and another coat applied less than 2 yrs ago seems to be doing even worse.
Any thoughts on whether the Waterlox is the right product to be using - and if not, suggestions on an alternative and associated prep work?
Thanks,
Mike