How-To use Same-Day Stain and Topcoat: Fiberglass Doors

Follow our helpful process here to make your next project a success and keep your door looking beautiful for longer.

Time Required: Icon_Time6_1d_2d_85gray-1 Difficulty: Icon_DiffLevel2_85gray-1


Tools Required

  1. Foam Brush
  2. A pair of one-size-fits-all gloves Icon_DisposableGloves_85gray-1
  3. A 3-inch natural brush (for stain) Icon_PaintBrush_85gray-01-1
  4. A 2-inch synthetic brush (for topcoat) Icon_PaintBrush_85gray-01-1
  5. One staining rag Icon_CleaningRag_85gray-1
  6. Two cleaning rags Icon_Rags_85gray-1

Materials Required

  1. Same Day Stain Kit (buy now on Therma-Tru Store)
  2. One 4-oz. bottle of mineral spirits
  3. One 16-oz. can of stain
  4. One 20-oz. can of topcoat (buy now on Therma-Tru Store)
  5. Two fiberglass test samples
  6. Two stir sticks
  7. Same-Day Stain step-by-step instructions

Step 1) Prep instruction & important notes


Consult the instruction pamphlet for important information prior to starting your project.


Step 2) Surface preparation


Use an abrasive pad to smooth out any blemishes on the surface of your door.


Following the abrasive pad, use a towel & mineral spirits to further smooth out any blemishes on the surface of your door.


Use sealant to fill any gaps between the glass insert and door (if applicable).


Use a scraper & glass cleaner to remove any excess sealant and any dirt or dust from the surface of the glass.


Lastly, tape off the glass insert and any other parts of the door you'd like to remain stain-free.


Step 3) Color test & apply stain (to sample)


Before applying stain, stir your Same-Day Stain can, (DO NOT SHAKE, shaking can cause bubbles in the stain) to ensure proper color & consistency. 


Apply stain to test sample in circular pattern, then even out the stain by wiping with the grain. Allow to dry 10-15 minutes, then using a dry rag wipe with the grain to remove excess stain and reach your desired color. For darker colors, reapply stain in multiple coats. 


If the color is not as desired, you can repeat the process by removing the stain on the sample with mineral spirits and a rag. Allow to dry before re-staining.


Step 4) Apply stain (to door)


Use the foam brush or rag to begin applying stain to the door in the following order: Begin with staining the glass frame (if applicable), then the deep groves in the door panels, the interior panels, interior flat sections, exterior flat sections, then door frame, edges, brickmoulds, mullions, and astragals. 


Remember to use the foam brush or staining rag to work the stain in a circular motion across the grain on the door, and wipe with the grain to even-out any dark or light spots. Allow to dry for 10-15 minutes then use a clean rag to even out the stain coat. For darker applications, allow the stain to dry for 2-4 hours, then apply another coat. To complete the process, turn the door to the other side and repeat the above processes of step 4.


To ensure an even coat, use the 3 inch natural brush to blend the stain across the surface of the door. 


Step 5) Test for dryness


Stain your second sample piece after completing your door. Allow stain on test sample to dry for 4-6 hours. To test dryness prior to applying topcoat, apply masking or painters tape to the sample, then peel it off. If the tape removes cleanly then your sample and door are dry and ready for the final step.


Step 6) Apply protective topcoat


Similarly to the stain, be sure to stir the topcoat prior to use (DO NOT SHAKE, shaking can create bubbles that hamper application). Note: do not use topcoat that is more than 3 years old or has been frozen.


Practice applying topcoat in smooth consistent strokes to the dried sample piece. 

NOTE: Do not saturate your synthetic brush with topcoat, only lightly wet the tip of the brush for more consistent application.


Once ready, begin applying topcoat to the door in long, smooth strokes. Do not use excessive strokes as that may cause uneven build-up of topcoat. Be sure to apply the coat thinly, and work in the same order as you did with the stain, beginning with the interior window frame. 


Do not worry if the topcoat appears milky in color, as it drys it will become completely clear. Once done with side one, repeat the process on the other side. Allow 2-3 hours for the first layer to dry. Then apply another layer of topcoat. Allow to dry, then re-install your door. Repeat this entire process as needed to maintain the proper color of your door. Typically every 3-5 years.