How to Paint Glass Fiber

Updated July 20, 2017

Glass fibres are used in multiple applications from insulation to the bodies of sports cars. It is normally painted after it is combined with a resin to form fibreglass sheets. The sheets are painted for cosmetic reasons as well as to protect the resin holding the fibres together from degradation by water and light. In order to make sure the paint firmly bonds to the surface of the fibres, it must be properly prepared to receive the paint.

Clean the surface of all debris, oils, water and grease using the paper towels.

Paint on a light coat of primer and allow to dry completely.

Lightly sand the surface with 120 grit sand paper. Remove any dust from the surface.

Spray a thin layer of paint equally over the entire surface. Remove any dust from the surface.

Wait for the paint to fully dry, then lightly sand with 400 grit sand paper. Remove any dust from the surface.

Repaint the surface followed by light sanding using 1,000 grit sand paper. Remove any dust from the surface.

Spray on a thin clear coat of sealant to protect the paint.

Buff out the clear coat to a high shine.


For the paint to properly set up, the painting should be performed at room temperature and at less than 50 per cent humidity.


Spray painting should be done in a well ventilated area.

Things You'll Need

  • Fibreglass sheet
  • Paper towels
  • 120, 400 & 1,000 grit sand paper
  • Spray painter
  • Primer
  • Polyester or Polyurethane based paint
  • Clear coat polyester or polyurethane
  • Hand buffer
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