Sun damage is irreversible. If you’re starting to see it, now’s the time to address it. Sun damage can become character if the door has a good finish on it. Varnished or oiled doors are the most vulnerable and even one coat of finish will put the damage on hold for a short time.
Does you entry door tell your visitors of the pride you take in your home. Does it welcome them in? Is this the first impression that you don’t get a second one of? You see it every day and you don’t see it change. Take a look today or tomorrow. Is it looking dry and cracked? Do you have other wooden doors on the outside of your home? Now is the time to protect them from the summer sun. They certainly would be expensive to replace.
A proper paint or varnish job is the key to long term protection and beauty. Basic painting techniques apply. If your home was built in 1978 or before, check out the government website below prior to starting any work that might make dust:
http://www.pueblo.gsa.gov/cic_text/housing/finlead/leadhelp.html
Assuming lead is not an issue, you may proceed with the following.
Make sure the surface is clean and sand or scrape to remove any loose or peeling paint or varnish.
Next apply a coat of varnish or primer. This will seal the wood.
In the case of a painted door provide a good surface to caulk or putty to if necessary.
In the case of varnish the wood will have changed color, if you should opt to putty or patch you’ll be able to pick a color that will be close to the finished door. In most cases damaged wood will get darker when sealed. If you feel that stain might be needed, wet the wood with water or solvent prior to the first coat of varnish. Everything that turns dark with the wetting will get at least that dark when stained. Areas that don’t change color or change very little will probably react the same way with the stain.
One or two more coats of the finish enamel or varnish will finish the job. Sand lightly between coats to remove any dust or debris that may have stuck to your door. If the finish looks a little uneven or like part soaked in, then give the third coat. If it doesn’t change the appearance, then it’s probably a texture difference you’re seeing and additional coats won’t change it much.
Varnished doors should be evaluated every year, especially if they get a lot of sun.
I prefer not to paint the door I just use some natural oil and the wooden door look better.
That is my favorite finish also. Even if you let it get really dried out looking it can be brought back to almost new. A varnished door ignored as long will always look abused.