Staining a Fiberglass Door

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.




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39 Comments

  1. Steve Pulliam
    Posted March 1, 2015 at 8:12 pm | Permalink

    We have a wood grain fiberglass door that has been painted white. Can this door be stained with a gel stain so that it will look like a wood door? And if so, how would I do this?

  2. Posted March 1, 2015 at 9:08 pm | Permalink

    Yes,it is possible. To do this you will need to do one of 2 things;

    1- if the door and existing paint is in good shape, paint the door with a satin oil base paint with a medium or light tan color. This will be the background color for the gel stain. Now stain and finish as usual.

    2- Strip off the existing paint down to the unfinished original surface, apply stain and finish as usual. Be careful to choose a fiberglass safe paint stripper.

  3. Debra Collins
    Posted June 22, 2016 at 5:18 pm | Permalink

    I want to use gel stain on my fiberglass wood grain door the molding is a primed from Factory can I use the gel on the primed Factory molding and what kind of oil should I use?

  4. Posted June 24, 2016 at 2:56 am | Permalink

    Yes a gel stain can go over the primed molding. Any good gel stain will work, Old Masters is a good brand.

  5. Amie
    Posted July 12, 2016 at 2:17 am | Permalink

    Do we have to use a clear coat? Or can we just use the stain? I’m worried when it’s time to repair that it’ll be more work to remove the clear coat before staining?

    • Posted July 19, 2016 at 1:41 pm | Permalink

      A clear coat must be used over the stain. Gel or wood stain alone has very little protective power and must be protected from the elements with a suitable clear coat.

      • Charles
        Posted May 5, 2017 at 4:02 pm | Permalink

        Clear coat aka top coat??

        • Posted May 9, 2017 at 1:06 pm | Permalink

          Yes, they are the same thing. Varnish, polyurethane, etc are all suitable clear coats that can be used on top of a stain.

  6. Christina
    Posted August 13, 2016 at 5:46 pm | Permalink

    After staining and applying top coat, my husband noticed that the stain was darker on one side than the other. Can I put another coat of stain on top of top coat to darken the door?

    • Posted August 13, 2016 at 8:30 pm | Permalink

      Yes, a second is possible. Make sure to wait for the first coat to dry completely, typically several hours or overnight. If you apply the second coat to soon it could reactivate the first coat smearing it around.

  7. Stacy Davis
    Posted October 11, 2016 at 11:16 am | Permalink

    I need to strip the stain and top coat to restrain my 3 year old fiberglass door. I used gel stain and a polyurethane topcoat over factory base. What is the best product and process to use to strip topcoat and stain?

  8. Posted October 22, 2016 at 2:08 pm | Permalink

    Choose a paint stripper that is fiberglass safe then test it on a small spot to make sure it won’t harm your door. Klean-Strip Fiberglass Paint Stripper is one of the best and is fiberglass safe. Process: Use plastic scrapers and soft nylon brushes, don’t want to scratch the door while trying to remove the finish and stain. Finish up with a washing with plain water. You might need to use Lacquer Thinner after the washing to remove some stubborn spots. This will take time and effort, don’t rush.

  9. Tiffany
    Posted April 15, 2017 at 2:55 am | Permalink

    Do you recommend one or two coats of stain? I just worry that with 2 coats it may just look painted. Is one coat durable enough with the urethane coat?
    Thanks
    Tiffany

    • Posted April 15, 2017 at 1:00 pm | Permalink

      More than one coat of stain is just about the look. You can use as many coats as you feel is needed to get the look your after. I would do two coats of urethane for a more durable finish.

  10. Kevin
    Posted May 15, 2017 at 3:00 pm | Permalink

    What type of urethane would you recommend over a fiberglass door with gel stain finish? Would Minwax Indoor/Outdoor Helmsman Spar Urethane work?

    • Posted May 19, 2017 at 2:57 pm | Permalink

      The Helmsman spar will work well. I would stick with an oil base product for its ease of application but waterborne urethanes also will work, make sure what is used is recommended for exterior use.

  11. Maureen Gaynor
    Posted July 24, 2017 at 11:10 pm | Permalink

    Is it possible to get a light oak finish over the tan base of a fiberglass door, or will I have to prime it in a buff tone? Seems that mid tone and darker gel stains are all that I am seeing applied successfully. Also, does the interior side require a top coat?

    • Posted July 26, 2017 at 1:21 pm | Permalink

      The light oak color is very difficult to achieve over typical dark tan fiberglass. The buff color will be needed. Try to choose an eggshell sheened oil base paint if available, easier to stain over. Plus Old Masters makes the best gel stains, in my opinion. Here’s an example of the color needed (Driftwood by Old Masters) – http://myoldmasters.com/color/driftwood/. Here’s what Golden Oak stain looks like over Driftwood, stain applied with graining tool, http://myoldmasters.com/color/golden-oak-on-driftwood/.

      Yes you need to seal the inside of the door as well.

  12. Bever
    Posted July 25, 2017 at 6:10 pm | Permalink

    The lower section of our fiberglass door was weathered. I use a wiping stain instead of a gel stain. Color is fine but not sure what else to do or if I have to remove???

    • Posted July 26, 2017 at 1:09 pm | Permalink

      All you need t do now is apply a clear coat to protect the new stain color from the elements. Any exterior rated finish will work; varnish, polyurethane or water based acrylic.

  13. Sidney
    Posted August 20, 2017 at 9:32 pm | Permalink

    My dog scratched the door in several spots on my gel stained/exterior spar varnished door, and the color is fading. After washing and drying the door, I applied gel stain, but the scratches aren’t taking the stain. I have tried re-applying, using a touch up stain marker, with no success. Is there a touch up product for scratches on a fiberglass door?

    • Posted August 22, 2017 at 1:45 am | Permalink

      There are no other products I’m aware of that will work in this situation. It is possible the scratches are into and damaged the embossing (wood grain). It is impossible to fix this type of damage. Try an artist brush and the gel stain, carefully apply to the scratch only and reapply when dry if needed.

  14. Kate
    Posted September 5, 2017 at 3:26 pm | Permalink

    Can I use a solid color oil based stain instead of a gel stain on a fiberglass door?

    • Posted September 6, 2017 at 10:30 pm | Permalink

      Probably, but test for good adhesion first.

  15. Louise
    Posted September 5, 2017 at 5:46 pm | Permalink

    I have a thermatru wood grain front door that is under a porch roof, never receives sun or rain and the original mahogany colored gel stain was never top coated. 7 years later the door dulled because of cleaning with simple green or windex. To refinished this door I cleaned the inside and outside door with lemon pine sol as I read that this product did not require a rinse and did not leave a residue. Then my painter simply restained the door with 118 dark mahogany Zar oil based interior wood stain. One coat. The door is beautiful. My question is must I top coat? I would prefer not to because I may need to reapply another coat of stain and did not want to get involved with taking off the top coat. How long would this finish last without a top coat?

    • Posted September 6, 2017 at 10:35 pm | Permalink

      Top coating would be nice but since the door is well protected now it isn’t really needed. You should get a couple good years out of the new stain before recoating.

  16. Jeannie
    Posted September 26, 2017 at 9:44 pm | Permalink

    Just put the top coat on yesterday. Now the door is “filmy” and looks ready for Halloween. It looked beautiful with just stain. Can this be fixed?

    • Posted September 27, 2017 at 3:04 am | Permalink

      Need a little info; What top coat was used, how was it applied and what was the weather conditions? Plus, is the door finish cloudy? Can you describe “filmy”? This will help figure out what happened and how best to fix.

      • Jeannie
        Posted September 27, 2017 at 5:51 pm | Permalink

        It was the Therma Tru top coat that came with the Therma Tru stain. It was brushed on. The weather was mid eighties, clear. The door finish is not cloudy. It was beautiful. The top coat turned cloudy within an hour after applying it.

        • Posted September 28, 2017 at 12:56 pm | Permalink

          The weather was good and the stain looked good prior to applying the clear finish.

          If I remember correctly this finish is a water based exterior acrylic urethane. Brushing is very difficult with this finish, dries too quickly. Applying it too thick could cause this problem. It should dry/cure clear which could take a day or two.

          There isn’t anything that can be done with this finish except strip and redo with something else, an exterior oil based poly or varnish.

          You should call Therma-Tru and let them know what happened.

  17. Susan
    Posted October 3, 2017 at 5:13 pm | Permalink

    This is a very helpful thread.
    I have a Jeld-Wen patio door (fir texture) that I need to stain. The colors in the manufacturer’s offering do not match the wood trim in my dining room. I need to test some colors on fiberglass to be sure I have a good match but there was no sample included with the door. I wrote to Jeld-wen but have not been able to get a response. Is there a way to get a sample of fiberglass from some other source to test my stains? Can I test them on a different surface, like a board painted to match the base color of the door?
    Also, what do you recommend for a durable, long lasting outdoor top coat?
    Thank you.

    • Posted October 4, 2017 at 4:41 am | Permalink

      Unfortunately getting a piece of embossed fiberglass for stain matching isn’t easy, mostly impossible. Using a painted board is your best bet.

      McCluskey’s Man-o-War exterior spar varnish is a great durable finish. It is probably the toughest exterior clear coat you can get.

  18. Susan
    Posted October 22, 2017 at 9:46 am | Permalink

    I had the glass replaced in my fiberglass door and need to know how to stain plastic glasss trim to match stained door. This is on the interior side as we had exterior painted.

    • Posted October 22, 2017 at 9:00 pm | Permalink

      First you need to prime the plastic trim then paint it a medium tan color, this will match the original color of the door. Could also use a tinted primer, ask you local paint store if they can tint it to a tan color. Now you need some gel stain or heavy bodied wiping stain that matches or comes close to the door stain color. Application is by brush, might take more than one coat. Protect the rest of the door with blue painters tape and masking paper or news paper.

      After the stain is applied and dry apply a coat or 2 of sealer, polyurethane or varnish. Might be a good time to re-coat the entire door.

  19. Dagny
    Posted November 11, 2017 at 4:45 pm | Permalink

    I just had a ThermaTru fiberglass entry door installed. I painted the outside to avoid the weathering of stain. However, I wanted the wood look inside, so I stained it and the sidelights with Varathane gel stain, Ipswich Pine color, two coats. It looks beautiful now, before I have topcoated. I see someone commented that the inside needs to have a topcoat. Why? I’m worried that putting polyurethane on will ruin the look I have now; it might run or drip, or loosen the stain and make streaks or something. I’m hesitant to do any more since I love how it looks now. Please advise as to reasons for top coating the inside.

    • Posted November 12, 2017 at 9:54 pm | Permalink

      A clear coat will protect the stain from fading and damage. Applying a clear coat, varnish or poly, can be a challenge but careful and apply only thin coats problems can be minimized. I would choose an oil base finish, fast drying polyurethane is good. Water based finished can present problems as they dry too fast and are harder to apply by hand.

  20. ERIN
    Posted November 12, 2017 at 7:09 pm | Permalink

    I have just had a therma-try door installed. I stained both sides of the door yesterday afternoon and it came out nicely, other than having to pluck hairs off from the brush supplied with the Therma-try recommended Same Day Stain Kit. Door looks good but, after 24 hours it is still very wet/tacky. Do I need to remove more, even though the door looks good, or will it eventually dry. If I let it go too long without putting on the top coat will there be a problem? Temp yesterday was 67 with 70% humidity. today it is 72 wirh 67% humidity. Thank You!

    • Posted November 12, 2017 at 9:50 pm | Permalink

      Let it dry. With high humidity and somewhat low temps it could take a few days. Keep check it and when dry apply a clear coat to protect the good looking stain.

    • Dagny
      Posted November 12, 2017 at 11:10 pm | Permalink

      When I stained my Therma Tru door, even though the stain can said 24 hours, it really took more like four days for it to dry to not tacky at all! I live in Massachusetts and it’s fairly humid so maybe that’s why. But it did eventually dry completely.

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