How to clean dull fiberglass

Updated February 21, 2017

Fibreglass is a durable product that is used to construct shower inserts, boats and other outdoor vehicles. All new fibreglass contains a clear polish, called a gel coat, which protects the material from damage and maintains an attractive appearance. Over time, the gel coat becomes scratched or covered in soap scum and oxidation which makes the fibreglass appear dull. Restoring the shine to fibreglass requires a thorough cleaning and polishing.

Fill a 5-gallon bucket with 1 gallon of water and 1 cup of liquid washing powder. Mix the solution to dissolve the soap.

Insert a sponge into the bucket and wash the entire surface of the fibreglass to remove dirt and dust. Rinse the fibreglass with clean water to remove all traces of the soap residue and allow it to dry.

Apply 1/2 to 1 cup of acetone to a cloth and wipe down the entire surface of the fibreglass with the cloth. The acetone removes any surface grease that the soap did not remove.

Polish the fibreglass surface with an abrasive, rubbing compound to remove small dents and imperfections. Apply 1 tbsp of rubbing compound to a rag and rub the fibreglass in circular motions until the surface looks smooth. When the entire surface has been polished, wipe it down with a clean towel to remove excess rubbing compound.

Apply 1 to 2 tsp of liquid automotive wax to a lint-free towel. Apply the mixture to the fibreglass surface using circular motions until the entire surface is covered.

Rub the surface of the fibreglass lightly with a clean, lint-free cloth to remove wax streaks and buff to a shine.


If the fibreglass surface has mildew on it, add 1 cup of bleach to the soap and water solution in Step 1. Wear gloves when cleaning to protect your hands from acetone.

Things You'll Need

  • 5-gallon bucket
  • 1 gallon water
  • 1 cup liquid washing powder
  • 1 cup bleach
  • Sponge
  • Lint-free cloths
  • Acetone
  • Rubbing compound
  • Automotive wax
  • Gloves
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About the Author

Kimberly Johnson is a freelance writer whose articles have appeared in various online publications including eHow, Suite101 and Examiner. She has a degree in journalism from the University of Georgia and began writing professionally in 2001.