How to Paint Over Old Fiberglass

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Things You'll Need

  • Dish detergent

  • Clean rags

  • 120 grit sandpaper

  • Epoxy filler

  • Polyurethane paint

  • Paint brush

Fiberglass is not always smooth and must be evaluated carefully for cracks.

A fresh coat of paint may bring an old fiberglass boat or greenhouse back to life. Fiberglass is light and often used for construction of such items as hot tubs, boats and greenhouses. When the paint on these items fades or wears, the visual value falls. Repainting requires a bit of work, but the results can transform the item to like-new condition.


Step 1

Wash off dirt and debris using a mixture of dish washing detergent and water. Scrub with a clean cloth.

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Step 2

Inspect the fiberglass for any cracks or holes. Fill these cracks with epoxy filler according to the manufacturer's directions and allow to dry.


Step 3

Sand the fiberglass lightly using 120-grit sandpaper. Do not flake off the fiberglass. Remove only surface paint, wax or other finishes.

Step 4

Paint the fiberglass with polyurethane paint. The paint is thin and will require several layers. Allow the paint to dry between layer applications according to the manufacturer's directions.


A hand sander will make the sanding process go faster for the do-it-yourselfer.


Spot painting using this process will leave obvious flaws. Paint the entire item for best results.


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