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ARK Fiberglass Repair Instructions



  • For light weight fibreglass such on small boats, ATVs, etc use a sander with coarse (40 grit) sandpaper to remove Gelcoat or paint for at least 2” around damaged area. Continue sanding until all damaged fibreglass has been removed. Delimitation will show up in white patches, remove this as well. A mini grinder with a course resin fibre disk will work faster on heavier glass.
  • Fibreglass will not cover open gaps, so holes will have to be backstopped. If you can get at the backside of the damaged area cover the gap with 3 or 4 layers of masking tape.  If you can’t get at the inside cut a piece of heavy cardboard or plastic (Yogurt container tops work well) so it will just fit through the widest part of the hole.  Put a piece of string or wire through the center of this piece, tie a knot on the back.  Push the backstop through the gap, tie off the string or use double sided tape or 5 minute epoxy to hold in place.
  • Use scissors to cut the first piece of fibreglass so it is just covers the sanded area, cut subsequent pieces slightly smaller so you can avoid a bump around the outside edge. Fibreglass bodies on most ATV’s and PWC’s are about 1/8” 3mm thick, 3 layers of glass will fill back to the original thickness.  For thicker fibreglass just add more layers. 
  • You can mask the area around the repair to avoid drips and runs on the surrounding area but the masking should be removed as soon as the resin gels.


  1. Fill the enclosed mixing container about ¾ (1.5 oz.) full with resin. Add 12 drops of hardener, stir, when the resin darkens it is ready to use. Brush a thin layer of the catalyzed resin on the sanded area.  Place the largest piece of fibreglass over the wet resin, use a brush to work the glass into the resin, add just enough resin to wet out the first piece of fibreglass, apply the next piece over the first, add more resin as necessary and repeat until you have used all the cut material.  A plastic spreader or over the limit credit card can be used to smooth the wet glass and remove excess resin.
  2. TIPS: Do not use any more resin than is necessary to make the fibreglass go transparent, excess resin will just run out. The resin will take a minute or so to saturate the glass so be patient. The catalyzed resin should last in the mixing pot for 10 to 15 minutes, if it starts to get warm discard and mix a fresh batch. Ideal working temperature is 20C, below 10C the resin may not cure properly, over 25C will reduce working time.  Avoid working in direct sunlight.


  1. The patch should cure hard in 2 to 4 hours. Sand smooth and flush to the surrounding area with 80 grit paper.   Low areas can be filled by adding micro balloons to a small amount of resin until you get thick putty, add catalyst and apply with a spreader.  For small amounts of filler any dry powder can be added to the resin, such as fiberglass, sanding dust, Arkfill, 3M Bubbles, baking flower, etc.
  2. Sand with 220 grit paper before painting or use an ARK GELCOAT REPAIR KIT to match and blend to your original color.

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