Photo Images: Kit Latham
Long ago, I watched out next door neighbor painstakingly strip the paint off, sand, stain and seal his west-facing front door. The next year he was sanding and refinishing it again. What gives? I wondered. He said the hot afternoon sun had fried the finish. He was now wiser and decided to try marine Spar, a urethane varnish used for boats. He then made it through 2 full summers without
a touchup. Even with a heavy duty finish, stained wood with a clear finish will need periodic touchups every few years. You'll need to sand away the damaged top layers and refinish with a few fresh coats of the finish. You also want to keep moisture from "wicking" up through the unfinished wood on the bottom edge of the door. Take it from me, the moisture will cause warping and you'll have closing problems. Moisture in wood-BAD, sealed wood-GOOD!
There are many online tutorials to show you step by step what you need to know to refinish a solid wood front door. I always trust the good old boys on This Old House. I wish they were my next door neighbors.