I stained my door and put 3 coats of polyurethane on it last year. Now little bits of stain have worn away. After I strip it and before I stain it will I have to prime it? What kind of polyurethane should I use that will last?
No need for primer after removing all stain and finish. The fiberglass will be its original color, light tan. This will be a good base for the new stain. I'm not a big fan of using polyurethane on these doors. Use either McCloskey's Man-O-War spar varnish or exterior Varathane Diamond Spar Urethane. Both of these hold up well. The stain also has a lot of effect on how long the finish lasts. My favorite is Old Master gel stains.