A step-by-step look at a repair to a polyethylene kayak scupper using West Systems G/Flex epoxy system

We recently had a customer bring a Mirage kayak back to us with some fairly major damage. 
It looks like the kayak cart was plugged into the wrong set of holes. The cart did not sit properly and caused the damage seen below. 
Original Hole 
We thought this would be the perfect opportunity to try West System's G/Flex epoxy. This gap filling epoxy will bond to most materials. (For more information on the G/Flex system read the Epoxyworks article here .)
As with any repair job the surface preparation is extremely important. Most repairs fail due to contaminants. The following steps prepared the surface for the epoxy.


Bevel the edges of the crack - using a chisel both edges of the crack were bevelled to maximize the surface area for the bond.
Bevel the Damaged Area
Sand the area - an 80 grit sandpaper was used to smooth the area and to rough up the surface to increse the bond strength
Sanded Area Around Crack
Wipe the area with a solvent - the entire area was wiped down with a paper towel and acetone. I prefer paper towel for this over rags to reduce the chance of contaminants from the rag being left on the repair surface.

Flame the area - a torch with a loose flame was played over the repair area. The flame is quickly passed over the area several times to ensure complete coverage and to reduce the chance of damage. 
I am not sure exactly what is accomplished when flame treating the surface. I have been told at various times that it oxidizes the surface, it burns off an oily layer that comes from the plastic, or that it excites the electrons in the plastic's molecular structure. All seem possible (although I think the oxidizing seems simplest) but it is definitely a necessary step. It is highlighted in the West System instructions.

Flame treating the area definitely increases the bond strength when working with the polyethylene plastics.
Apply a Weak Flame to the Prepared Surface


The G/Flex kit that we were using was the 655-K G/flex Thickened Epoxy Adhesive Repair Kit. 
The kit included:

  • 4.5 fl. oz. G/flex 655 resin
  • 4.5 fl. oz. G/flex 655 hardener (9 fl. oz. of mixed epoxy)
  • 2 reusable mixing stick/applicators
  • 4 alcohol cleaning pads
  • 1 pair disposable neoprene gloves
  • 10 mixing palettes
  • detailed handling and repair instructions

The directions included in the box were very detailed and easy to follow. I used one of the mixing palettes to measure out equal amounts of the resin and hardener, it was as simple as putting toothpaste on a toothbrush. I mixed the two parts thoroughly and continued to mix them for about 5 minutes.
I applied the epoxy to the hull using one of the included applicators. The flat edge was excellent for use on the hull while the rounded end was perfect to work the epoxy into the scupper hole. I did not attempt to smooth the epoxy too much as I wanted a strong bond and was not as concerned with appearance. The epoxy was left to cure overnight.
GFlex Expoxied Repair Before Finishing

After 24 hours we tested the hull by loading the hull around the repair. The epoxy was thoroughly bonded to the plastic and the entire hull deformed as a single piece.

The entire repair took between 45 and 75 min, between interruptions. It was simple and required the minimum of tools and knowledge. The torch was the most difficult tool to use and obtain. The epoxy was easy to work with and adhered to the plastic.
I would definitely recommend this system to anyone needing a similar repair.


Tags: kayak, repair, GFlex, tutorial

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