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Gelcoat Repair Kit Instructions


  1. Clean the damaged area with Acetone to remove wax and dirt.
  2. Sand with coarse paper overlapping the damaged area by about 2”, followed by medium and fine, to get too original color. Remove dust with Acetone.  If the fiberglass underneath is visible and shows signs of delimitation, white, or puncture, repair with an Ark Fibreglass Repair Kit.
  3. To tint for off-white using a toothpick add very small amounts of pigment to White Gelcoat, and mix thoroughly. For coloured hulls add pigment to neutral Gelcoat.  Use only a small amount of gelcoat in a separate mixing cup. Test the colour on the sanded area, avoiding direct sunlight as this can ‘trick’ the eye and make matching more difficult. If the pigmented gelcoat becomes too dark, use this gelcoat to tint a new batch of white, as it is easier to control the pigment amount when premixed with Gelcoat.
  4. The colour you make will remain unchanged when cured, however, too much hardener can ‘burn’ or discolour the Gelcoat. Divide the colour-matched Gelcoat into 2 or 3 batches to apply two coats and save some in case you need a touch-up.  Carefully add no more than 10 drops per ounce of Gelcoat to one batch, do not over catalyze. Working time is 15-20 minutes, much less in direct sunlight.

* N.B. – The hardener MEKP is poisonous and corrosive. Use caution when handling this material

  1. Using a spreader (a credit card works well) or brush apply catalyzed Gelcoat smoothly and evenly to the repair area, leaving the new Gelcoat slightly higher than the substrate. You may find it useful to tape around the repair with 1 or 2 layers of masking tape, to keep the Gelcoat confined to the repair area.  On vertical surfaces the Gelcoat will run if it is too thick, apply a second coat as soon as the first starts to gel, about 30 minutes. Remove masking tape as soon as the last coat starts to get tacky.
  2. Once cured (at least 3 hours at 20C/70F) wipe with Acetone. Wrap the course waterproof sandpaper around the block, dip in clean water, sand the repair smooth tapering the edge into original Gelcoat, wash sanding dust out of the paper as it fills.  Use the medium and fine to finish.   If the gelcoat “balls” when you start sanding it is not hard enough, wait until it cures fully.  Finally, polish with the compound, overnight cure is best for achieving high gloss.
Tinting From White Base Colour From a Neutral Base
Ivory - Add Yellow Oxide Start with the pigment closest to the predominant colour.
Add other pigments for shading
Grey/White – Add Black
Smoke Whites – Add Yellow and Black
Beige – Add Red Oxide

Do not work in direct sunlight or rain

Gelcoat adheres well to fiberglass (polyester) resin and repairs done with Epoxy resin, but may pop off of large Epoxy surfaces if it is hit.

Click here to download these instructions for offline use