An exterior fiberglass door combines the appealing qualities of a wood door with none of the warping problems that can result from water seeping into the wood. Fiberglass exterior doors do need periodic maintenance to keep up their protective finishes. Following some basic cleaning tips will go a long way towards preserving the life of your door.

Door Stain and Clear Coats

Fiberglass doors are initially stained with oil based colored pigments that can range from light blonde to deep mahogany and are meant to give them the appearance of genuine wood. They are then sealed with a clear coat that is similar to the protective urethane coats used on wood. Once the gloss on the fiberglass has started to become dull, this is a good indication it is time for a new coat.

While the difference from wood is that fiberglass will not lose its shape from wear and tear, its clear protective finish can eventually be worn away by direct sunlight, rain, wind, and other elements of nature.

Correct Fiberglass Cleaning

When the time comes to reapply a new coat of stain and clear finish to your fiberglass door, the first step is to make sure you are working with a clean surface. It is recommended to use a fiberglass staining and finishing kit, available at major hardware retailers. These kits should include a fiberglass safe cleaner; if not, check the manufacturer’s specifications for an approved cleaning compound. Do not clean fiberglass with soap or any other type of household cleanser; doing so can leave film and residue behind that will not allow the stain and clear coating to work correctly.

Some fiberglass staining and refinishing kits come with a small sample piece of unsealed fiberglass; this is meant to give you a guideline to help determine how much the clear coating on your fiberglass door has worn down. Apply a clear coating to the piece of fiberglass according to instructions and keep it indoors in a cool, dry place. Each year, compare the finish of this piece with that of your exterior door; this will give you an idea of whether the door itself needs a new coating.     

Optimal Temperature

How hot or cold the surrounding air is can have an impact on fiberglass doors when reapplying stain and finish. Most door manufacturers recommend working out of direct sunlight and only in temperatures between 50 and 90 degrees. One option is to refinish your door inside your garage; just make sure to leave the garage door up for ventilation. Also try to avoid doing this project on windy days to prevent the new coats of stain from drying too quickly.

Light Vs. Dark Stains

Some fiberglass staining and refinishing kits specify different drying times between coats for light and dark colored stains. Follow these instructions carefully, since waiting too long or too short a time can result in a blotchy appearance on your door. Most fiberglass door stains have a minimum drying time of several days once you apply all coats of stain. After this, apply your final thin coats of clear finish.