How to Make a Homemade Gel Coat From Bondo

Mix your own homemade gel coat.
Mix your own homemade gel coat. (Image: Stockbyte/Stockbyte/Getty Images)

A gel coat is a specialized resin often used for the surface coat on fiberglass products. It is thicker than standard resin, allowing you to build up a solid shell before adding layers of fiberglass. You can make your own gel coat using fiberglass resin and Bondo auto body filler. This gel coat has a pink color, and makes it easy to visually inspect for thin spots. The mixture is also often less expensive than commercial gel coat.

Things You'll Need

  • Bucket with lid
  • Bondo auto body filler
  • Polyester fiberglass resin
  • Paint stick
  • Marker
  • Bondo catalyst
  • Resin catalyst
  • Paper bucket

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Empty a container of Bondo auto body filler into a 1 gallon bucket with a snap-on lid.

Add an equal amount of fiberglass resin to the Bondo.

Mix the two components together into a creamy paste using a paint stick. Mix slowly to avoid introducing air bubbles.

Seal the lid onto the bucket. Use a marker to write the amount of catalyst required from both the Bondo and resin instructions onto the bucket.

Store the mixture in a cool place.

Tips & Warnings

  • To use the homemade gel coat, measure out the amount that you need in a paper bucket. Mix in the proper amount of both Bondo catalyst and resin catalyst, following the mixing ratios that you copies from the original containers.


  • "The Prop Builder's Molding & Casting Handbook"; Thurston James; 1989
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