Changing the colour of your fiberglass bathtub

If you have a Fiberglass shower or tub that’s a light tan, blue, almond or spray painted bathroomsome other ugly colour  and you want to change the color to a nice brilliant white or the latest shade of grey to match in with the rest of your bathroom then just follow these simple steps.

Repainting your bathtub, shower unit 

Preparation is the key here and if you skip on the preparation you will have a mess on your hands so do yourself a favor and take your time don’t rush!

Step 1.

Clean the bathtub with Hydrochloric/ Muratic Acid {warning on this nasty acid}  option use white spirits if it is badly soiled use it neat then use a spray bottle to apply it and a clean damp lint free cloth to wipe off.

Step 2

Sand the entire area to be painted with P320 grit Sandpaper you don’t want to sand through the gel coat you simply want to abrasive the surface and remove the shiny, slick surface so the new paint can bond to the surface, when  the finish becomes flat and dull move onto the next step.

Step 3

Clean the shower with Hydrochloric/ Muratic Acid {warning on this nasty acid} option use white spirits, you can dilute the acid 3 parts water to one part acid, same as before spray on, then rinse the entire surface with water and let dry completely.

Step 4.


You have to spray paint the units! you can brush paint but it won’t be as good a finish.

A. Spray painting with aerosol/rattle cans

You will have to use a 2k/Aerosol paint which has direct adhesion to fibreglass,  the standard aerosol/rattle cans aren’t strong enough.

  • Mask up everything in the bathroom and I mean everything that you don’t want to paint.
  • Use a tack cloth to remove any dust
  • Activate the 2k/spraycan and shake for a least 2minutes
  • Start spraying from the top down, spraying a full coat of paint.
  • Apply two to three coats of spray paint allowing 10-15 minute between coats, do not! sand between coats.
  •   When you have finished spraying allow 1 hour  for the paint to partially dry, then very carefully remove all masking tape then do not use the bathtub for seven days this time is based on room temperature.

Spray painting using a HVLP spray gun this will be more cost effective if you are doing a complete bathroom.

The application process will be the same as above.

The mixing of the paint 2K uni paint

For Hi-gloss         2 parts paint  : 1 part Hardener:  Thinners 15-20%

For Satin finish (25% gloss level)    3 parts paint  1 part Hardener:  Thinners 15-20%

Painting by brush or roller

Mix up the paint same as above but don’t add any thinner

  • Use a short pile (Glossing) roller or a mohair brush be warned you won’t be able to clean these the paint is solvent 2k acrylic.
  • Apply one even coat leave for twenty four hours and apply a second coat.


The type of paint you will need to use is described as 2K polyacrylic DTM Universal which has direct adhesion to fiberglass without the need for a primer, I have inserted links to all the product these links go to a ecommerce website.

Somethings to keep in mind.

  • if you go for the Hi-Gloss finish it will be easier to clean but! it will also be very slippy when wet, you can add grit to the paint on the standing areas about 10-15%
  •  don’t use harsh cleaning products on the painted surface.
  • wear protective clothing and a good quality face mask,  goggles, nitrile gloves.
  • Make sure you have good ventilation and if you have breathing problems then don’t use this paint in fact don’t use any paints.

Best of luck with your project.