The other option is wood boat bright work and use spar varnish but realize boat coatings are made to be removed and renewed periodically so the same will happen to your door.
Best way to finish exterior wood door.
My go to finish system for exterior doors is a combination of two products.
Penetrating finishes harden in the wood.
Use varnish with compatible stain.
Their popularity and effectiveness for finishing the bright work on boats makes them the best choice for protecting exterior wooden doors that are exposed to harsh weather elements year round.
Don t sand too much.
Pettit marine paint s captain s varnish and epifanes wood finish matte.
Clean the door and coat it with sikkens and a foam brush and wait for it to dry.
An extra smooth surface will not absorb stain as well as a rough surface.
The first option would be using a penetrating finish such as watco exterior.
A second choice would.
These must be applied in multiple coats with meticulous initial and in between coat prep.
My go to finish system for exterior doors is a combination of two products.
Penetrating stains and marine varnish are a good start but clear finished doors will still need occasional maintenance.
Pettit marine paint s captain s varnish and epifanes wood finish matte.
Depending upon exposure you are good for another two to twenty years.
But a beautiful wood door with a clear finish will attract many more admiring glances as long as you maintain it with devotion.