Fiberglass doors are often preferred for their mold and rust resistance. Unlike wood, they will not deteriorate or swell. They can also be less expensive than wood and metal doors. While fiberglass doors can be painted, there is a bit more effort involved to ensure the finish lasts.
Painting fiberglass doors require some planning. As there are different types of fiberglass, there are different types of paint and knowing what to use for a proper bond is especially important. Types of fiberglass include epoxy resin and polyester-based resin. They require epoxy-based paint and polyester-based paint, respectively.
Details of Resin Types
Epoxy resin is the most expensive of the resin types, but it is also the strongest. Epoxy has a slight amber hue, so you might see a bit of yellow tint, not to be confused with yellowing from age. There are clear epoxies as well, so there may be no coloration to observe. Epoxy resin is also more waterproof than polyester-based resin.
Polyester resin is lower-cost, less waterproof, and more brittle. These distinctive features should hopefully allow you to determine which type of resin your door has.
Fiberglass, as with other materials, needs to primed first and then painted. Once you have determined the type of fiberglass on your door, you will need a primer that is compatible. Urethane, epoxy, and latex primers will work with most types of fiberglass and fiberglass paints. Always check the primer's label for recommended topcoat paints as well. Etching primers are not recommended because the etching chemistry isn't compatible with fiberglass.
Types of Paint
Fiberglass paints can be found with varying degrees of shine or gloss just like any other paint. There are high gloss, regular gloss, and flat finishes. As water and sunlight can weaken fiberglass over time, it is important to consider a paint that will endure these elements. Any paint you choose should be classed as exterior paint, as exterior paints are made to resist weathering. When choosing fiberglass paint, do not use oil-based or melamine; instead consider acrylic (100%), polyurethane, polyester, and epoxy paints.
Many manufacturers and painters will recommend that you do not mix primers and paints among various companies. For best results, they say to stick with one manufacturer for both applications. And, as mentioned earlier, you should also keep a consistent base between the fiberglass resin and paint; if the fiberglass is an epoxy resin, use an epoxy-based paint. Use a polyester-based paint for polyester-resin fiberglass.
Selecting the right primer and paint for your fiberglass door will provide the necessary bond. This will prevent peeling, bubbling, and flaking. It will also ensure your door's finish lasts a long time and that the fiberglass underneath is well protected.