Things You'll Need
2 soft cloths or rags
220-grit or higher sandpaper
Auto body filler with liquid hardener
Putty knife or plastic spatula
Trash bag or outdoor trash can
Nose-and-mouth mask (optional)
Removing nails, doorknobs, latches and other items from fiberglass doors leaves holes and possibly scratches. The holes are unattractive and can become a gateway for insects and moisture. Patching compound and materials used to fill holes in wood doors do not work for fiberglass doors. Filling holes in fiberglass doors requires a filler that is made for fiberglass components. Once the holes are filled, you may stain or paint the doors.
Cleaning and Sanding
Wipe the holes and surrounding areas with a soft cloth or rag to remove dust, dirt and other debris. Wear latex gloves to keep oils from your hands from transferring onto the doors.
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Sand the area surrounding the holes with a piece of 220-grit or higher sandpaper. Sanding roughs up the surface and the holes for filling.
Fold the soft cloth or rag in half, and use it to wipe the areas thoroughly, removing sandpaper dust and other debris.
Place about 2 cups of auto body filler in a plastic container.
Pour 1 tablespoon of the auto body filler's liquid hardener in the plastic container, and stir the mixture with a plastic spoon. The filler mixture will become softer. Pour an additional 1 tablespoon of liquid hardener in the plastic container, and continue stirring the filler mixture until it is thick paste and one uniform color.
Dip a putty knife or plastic spatula into the auto body filler mixture, and scoop out about 2 tablespoons. Spread the mixture into one hole. Re-dip the putty knife or spatula into the filler mixture if necessary, and continue spreading the mixture into the hole until it is filled.
Spread the mixture evenly on the area surrounding the hole and scrap off excess mixture. Repeat Section 2's Steps 3 and 4 for the each hole that needs filling in your fiberglass doors.
Let the filler mixture dry thoroughly where you filled holes, and then sand it and surrounding areas with a new piece of 220-grit or higher sandpaper. The areas should be smooth and flat. If you notice indentations, mix a new batch of auto body filler mixture and use it to fill the indentations.
Wipe the sanded areas to remove sandpaper dust and other debris before applying primer or paint. Dispose of the plastic spoon, plastic container used sandpaper, cloths or rags and latex gloves in a trash bag or outdoor trash can.
Wear a nose-and-mouth mask or work in a well-ventilated area if the odor of the auto body filler mixture bothers you.
Auto body filler is available at automotive supply stores.