Embossed fiberglass is a low maintenance substitute to the standard wood door. Plus, staining a fiberglass door can be easier than working with wood. The main difference between wood and fiberglass is the type of stain and its application.

Embossed, wood grained, fiberglass can’t absorb the stain like wood. A standard wiping stain will not work. The only type of stain that will work is a gel stain. The same type used on difficult to stain woods.

Some manufactures sell a stain and finish kit available in several different colors. The oil based gelled stains work great and the finish is a user friendly Acrylic Urethane or Waterborne Polyurethane. I have used the kits from Therma-Tru with very good results.

An alternative is to purchase the gel stain and finish separately. My preferred oil based gel stain is manufactured by Old Masters, available in multiple colors and can be intermixed to increase your color choices. The clear finish must be exterior rated, any quality finish can be used.

Procedures For Staining a Fiberglass Door

Staining a fiberglass door can be accomplished either hanging on the frame, attached to each other and vertical (multiple doors) or on saw horses. My preference when staining a fiberglass door is the vertical position and on the frame.

This way I don’t have to handle the door after staining. This is the procedure I will describe. Horizontal or vertical doesn’t matter as long as you are comfortable with the doors position.

1) Remove All Hardware and Weather Stripping

All door knobs and associated hardware has to be removed or carefully masked. Removal will allow the easiest staining and finishing experience.

The only problem is reinstalling a locking mechanism, typically the dead bolt, after staining. Be very careful at this important junction when finishing an exterior fiberglass door. It is very easy to damage the new stain and finish.

Next remove the weather stripping from the frame and the bottom of the door. Most manufactures have weather stripping and sweeps that will pull out. Store these items in a safe place for the duration of the finishing process.

2) Remove Excessive Window Glazing

If your fiberglass door has a window or sidelight(s) you will notice a rubberized caulking extruding onto the glass. Remove all excess glazing with a sharp single edge razor blade.

First carefully score the glazing along the edge of the frame. Using the razor blade scrape the glazing from the glass. Wipe the remaining residue off using a glass cleaner.

3) Clean the Door and Mask

Start with a clean surface by using mineral spirits and a clean white rag. This will remove any residue from manufacturing or shipping. Another solvent that can be used is denatured alcohol.

If excessive dirt or grime is present, soap and water must be used prior to cleaning with mineral spirits. Pay special attention to greasy fingerprints. Allow the door surface to dry completely before proceeding.

Stuck hard material must be carefully scraped off. Any scratch on the surface has the potential to be amplified after staining. Never sand a fiberglass door. It will be ruined.

The glass should be masked with safe release masking tape (blue painter’s tape) and paper. The extent of the masking depends on the application method of the clear finish, spraying requires the most masking.

4) Staining a Fiberglass Door and Sidelights

Two different methods can used, apply the stain with a rag then remove the excess with a brush or apply with a brush only then blend one area into another with the same brush. Both the rag and brush methods work fine.

I prefer to apply the oil based gel stain with a good bristle brush then blend one section into another with the same brush.

The best part about staining a fiberglass door is that any screw-ups can be removed with mineral spirits and a rag before the oil based stain dries. So you can practice on a flat area before committing yourself to staining the entire door.

Staining a fiberglass door using the brush method is easy. With a small amount of stain on the brush apply an even coat in the direction of the grain. Always begin in an unstained area working toward a previously stained area. Work the stain into the grained surface.

Use a fast light brushing technique, blending one section into another. During the blending process excessive stain can be removed from the brush with a clean dry rag. Continue brushing until one section is blended into an adjoining section.

Removing excessive stain with the brush, wiping the bristles on a rag to remove stain, can control the color intensity or a second coat can be applied after the first has fully dried, typically 24 hours.

The rag technique is very similar and is a good option. With this technique a rag is dipped into the stain and rubbed onto the surface. Rub in the direction of the grain. The brush is used to remove excess stain and blend one section into another. Excess stain on the brush is removed with a clean dry rag or paper towels. Allowing the stain to dry for several minutes before removing the excess will darken the color.

Experiment with both methods and consult with the door manufacturer to determine the best method for you.

5) Staining Sequence

Start with the door frame/jamb and brick mold, if made of stainable wood. If primed, staining and finishing is an option but painting looks better. Staining sidelights can be done after the door and the sequence is the same.

Staining a fiberglass door needs be done in a specific order.

• Begin with the door edges. Remove any excess stain deposited on the fiberglass face with a rag.
• Now it’s time for the face surfaces. Start with the raised panels and the vertical stile between them. Next is the window frame.
• Continue with the horizontal rails and complete with the vertical stiles. Always apply the stain in the direction of the grain.

6) Applying the Finish

A clear topcoat must be applied after staining a fiberglass door. Two application methods can be used, brushing or spraying. Both methods will produce great results, with the use of an HVLP sprayer producing the best results possible.

Multiple thin coats are better than two thick coats. Plan on 3-5 coats of clear finish depending on application method.

Provide a dust free environment. Do not sand between coats when finishing fiberglass doors. Dust can be removed with a tack cloth before application and between coats. Before beginning stir the topcoat well. Never shake the can, as this will cause fine bubbles to appear in the finish.

Brush Application
Apply a thin first coat so it just wets the surface. Quickly work the brush into the grained texture. Apply the finish in the same order as when staining. Observe the door for any runs or drips and quickly correct with the brush.

Do not over brush. Over brushing could loosen and lift the stain. If this occurs, wait until the finish is dry then gently wipe the area with a tack cloth to remove any balls of stain and finish. Carefully repair any damaged stain with a small brush then recoat the area before proceeding with the next coat.

Allow the first coat to thoroughly dry then apply another coat in the same order. Three coats are recommended for the best protection.

Spray Application
Either a HVLP or airless sprayer can be used. After filling and priming the sprayer test the sprayer pattern, pressure and volume on a piece of cardboard or plywood. Apply the topcoat in a sweeping motion, first in one direction and then in the opposite direction. Avoid spraying a heavy coat as drips or runs can occur, correct drips with a brush before the coat is dry.

Allow the first coat to dry before proceeding with the following coats. The second application needs to be sprayed the same as the first. Follow with one, or more, coats sprayed in one direction only.