My husband recently installed a new fiberglass exterior door on our house. I need to paint it and want to make certain I'm using the correct paint. It's already white so I assume it's been primed. Do I need to prime it again?
I'd prime it again anyway with Zinsser BIN or better yet their shellac based primer.
Then top coat with any decent quality high gloss latex paint. After a few weeks it won't look high gloss anymore but you'll get the best wear.
Thank you for your input.
According to Zinser's Primer Chart, the preferred primer for vinyl and fiberglas is the acrylic based Zinser 123. The shellac based "BIN" is not recommended for use on exterior surfaces ( except for spot priming of knots).
The finish coat can be either acrylic, oil or one of the new water based alkyds. Acrylics tend to be more color fast and gloss retentive. Their shortcoming is the gummy, tacky nature of the film, especially where the weatherstripping sits on the face of the door. It is not uncommon to have to budge the door with your shoulder to break it free of that stickiness! True oils or WB alkyds don't remain sticky.
The door manufacturer will have specific recommendations- check with them. I prefer oil-based alkyd enamels for doors as it offers a hard, durable and easy-to-clean finish that lasts longer than any water-based paint. It will yellow over time and should not be recoated directly with water-based finishes afterward (you then need a bonding primer). Any further applications of oil-based paint only requires a light sanding then direct application. Oil-based paints require a somewhat different application technique than water-based paints for the best results so if you don't have experience with them do a youtube search- lots of instructions for DIY there.