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What Is Epoxy Filler and How Is It Applied?

What is epoxy filler used for, on which damage, and how is it applied correctly? The basis of crack and void repair.

Epoxy filler is one of the most used materials in boat repair. This two-part system (resin + hardener) cures when mixed, structurally filling cracks, voids and unevenness.

What is it for?

  • Filling cracks and voids: closes damaged areas in fibreglass, wood and metal.
  • Fairing: creates a smooth base before painting (see surface prep).
  • Waterproofing: once cured, gives a durable, water-resistant fill.

Correct application

The surface must be clean, dry and grease-free. Resin and hardener are mixed in the right ratio; a wrong ratio ruins the cure. After curing it's sanded. Thin layers give fewer bubbles and better results than one thick layer.

Polyester filler or epoxy filler?

Epoxy filler bonds more strongly than polyester and is more waterproof; it's preferred for underwater and structural work. For the differences, see our polyester vs epoxy article.

We do structural repair and fairing under our fibreglass repair service with the right material and technique.

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