December 20, 2012

A look at gel-coat repairs

Inspect the gel-coat on your kayak for signs of wear and tear. The gel-coat is the colored shiny waterproof layer on the outside that protects the more porous fiberglass underneath. When it wears through or chips, the glass fibers exposed will gradually soak up water leading to more damage.

Look for places where the gel-coat has scratched or worn right through to the fiber beneath. These places may need touching up with matching gel-coat. Note any places where you have more significant damage that may need reinforcing with a fiberglass patch. Don’t forget to check the seam between the deck and hull and around the cockpit rim too. Once your kayak is completely dry you can use a marker pen to circle places you need to work on.

Cosmetic gel-coat repairs and touch-ups.

Small scratches and stains can be removed with a soft cloth and a water soluble buffing and polishing compound, such as Aqua-Blue 200 from Fiberlay. It will remove 600 profile surface scratches to leave the surface clean and shiny.

Gel-coat comes in two basic forms. The first is laminating gel-coat, which was used when your kayak was built. Laminating gel-coat is sprayed into the mold as a liquid and allowed to harden before layers of fiberglass are laid on top. The surface of the gel-coat remains sticky if air is not excluded, so although the surface against the mold hardens, the fiberglass is laid onto a sticky surface which aids bonding. Most repairs involving only gel-coat will be on top of solid fiberglass or gel-coat, and you won't want the outer surface to be sticky. You need the second form of gel-coat, a top-coat gel-coat.

The only difference between laminating and top-coat gel-coats is the latter has liquid wax mixed in. When you make a repair, the wax floats to the surface creating a skin, excluding air, and allowing the surface to harden. So once you've applied the gel-coat for your repair, don't keep touching it to see if it's set or you'll remove this film of wax and the repair will end up sticky to the touch.

To repair a chip in your gel-coat, roughen the damaged area with sandpaper to give the repair something to grip onto. Thoroughly stir your color-matched gel-coat to make sure the wax is stirred in. When stirring try not to introduce bubbles of air. It doesn't matter if the froth on your cappuccino coffee lasts until after you've finished your drink, but you don't want your gel-coat repair to be full of bubbles. Mix with the recommended volume of hardener. Now apply the mixture to the area needing repair, eliminating bubbles if possible. Your repair should dome a little higher than the original surface: it will shrink a little, and it's easier to file/sand off the excess than to fill low spots later.

Once your repair has hardened you can take off the excess using a file or wet-and-dry sandpaper and a block. Finally you can polish the area, using progressively finer wet-and-dry sandpaper, rinsing carefully between grades with fresh water. Once you reach 600 grade, you can finish the job with a polishing compound. A good repair will be almost invisible.

Note: matching gel-coat color is challenging. Pigment fades in sunlight, and manufacturers pigment batches vary slightly, so at best you'll get an approximate match, even when you bring in the help of a professional. Seaward Kayaks will be able to offer your closest match because they'll know the original gel-coat swatch color and gel-coat manufacturer.

Don't fret if your repair ends up visible. It's a badge that shows you use your kayak.


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