GRP is easy to fill with resin

Deeper damage, worn out cracks, air bubbles and holes in the glass fiber plastic (GRP) can be easily filled. Surfaces up to ten square centimeters can be easily repaired, moreover, a partial re-lamination should be considered. The fillers usually consist of resins.

Under and over water

If there is a repair on GRP, the filling of smaller damage surfaces with putty is easily possible. It should be noted, especially if the hull of a boat to be repaired that the filler is water resistant.

In the underwater area only two-component putty made of epoxy resin may be used. Polyester resins have the ability to absorb water, rendering them unusable for underwater use.

Filling or laminating

The boundary of the surface to be filled should be a size of about ten square centimeters. In the case of larger surfaces, structural damage may occur in the construction of GRP, which can not be compensated by pure filler.

The procedure is to be examined in detail, since the shape of the damaged area also plays a role. For larger and stability-relevant damage, a partial lamination should close the structure of the GRP again.

How to trowel GRP

  • Two-component epoxy resin fine filler or
  • Two-component polyester resin Feinspachtel
  • Harder
  • Osmose preservative
  • Abrasives with 80 to 200 grit
  • Hand sanding block
  • Cutter or carpet knife
  • spatula
  • Brush and roller
  • duct tape
  • Respiratory and eye protection
  • Full-body disposable overalls
  • rubber gloves
  • microfiber cloth

1. Preparation

Grind the damaged areas by hand. Cut the outer edges diagonally inwards, down to the bottom of the surface to be puttied. Remove the sanding dust with a damp microfibre cloth.

2. Prime osmosis protection

When the depth of the "wound" reaches the boundary between gelcoat and fiberglass, prime the surface with osmosis preservative.

3. Masking

Glue around the "excavated" surface, the boundary edges on impact of the upper edge end.

4. Mix the putty

Stir the putty according to the manufacturer's instructions and start to evenly fill in the exposed surface. Brush the putty from the inside to the outside. Immediately wipe off sticking scraps with a cloth.

5. Prevent air pockets

As with lamination, it is important to avoid trapped air. With the spatula, press the filler from more than one direction into the "wound".

Tips & Tricks

Fillers are available in fine, medium and coarse versions. Always choose products of the finest quality for GRP.

Video Board: Resin Casting Tips Tricks Tools and Hacks for your molding projects