Either by forming a hard film over wood or by penetrating it.
Clear coat for exterior wood door.
Through a process called photo degradation ultra violet uv radiation damages the wood and the finish.
Homeowners often wish to show the beauty of quality wood on exterior doors and trim with a clear finish.
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.
The finish will not hold up to the sun and weather requiring yet another refinish job.
Polyurethane is the most durable of clear exterior finishes.
Protecting the finish and wood from uv light choose a high quality long lasting clear finish for your beautiful exterior hardwood doors.
Application ease and service life are the two major differences between these finishes.
Exterior oil exterior varnish and an epoxy sealer with an exterior varnish topcoat.
Polyurethane wood finishes are synthetic coatings that prove highly durable and water resistant making them the best clear coat for wood protection.
Clean the door and coat it with sikkens and a foam brush and wait for it to dry.
Of the three clear exterior finishes exterior oil is by far the simplest finish to apply.
Depending upon exposure you are good for another two to twenty years.
At the surface of the wood uv breaks down the glue called lignin that holds the wood fibers together.
The film forming products both classic varnishes and modern urethanes are unmatched in their ability to bring out the beauty and depth of a wood surface while guarding against wear and tear.
Clear finishes work in one of two ways.