treatment for sun damage to carbon fiber

How would you repair/refinish a carbon fiber kayak with sun damage. Any suggestions?

I will likely head over to the local West Marine store to see if they have any advice, but I wanted to start with the paddling crowd. I’d appreciate any help you could offer.

What’s the nature of the sun damage?

Talk to the kayak’s manufacturer.
Remember that sun does not damage carbon fibers at all. If you’re seeing chalking of the resin, it helps to know whether vinyester resin was used, or (less likely) epoxy. Vinylester resin has some UV resistance, not a lot. Epoxy is more easily degraded by UV, but sometimes is partially protected by additives.

You need for the manufacturer to tell you whether there is a clear gelcoat over the carbon. Gelcoats are never epoxy based. You want to know whether discoloration can be removed by sanding, without cutting into the carbon cloth.

I guess resurfacing options would include painting, application of more clear (or pigmented) gelcoat, rolling on West 107/207 epoxy (I’ve done it but don’t recommend it), or just spot surfacing and use of 303.

By the way, kayaks with the carbon exposed on the outside are very rare. How did you end up with one?

My solution would be to just use the boat. Ugly boats don’t get stolen as often.

Not really rare…
Kayaks with carbon and clear finish especially on the hull are not really rare. Some manufacturers offer it such as Impex and Necky.

Agree that it would be importaint to find out the exact composition before trying any repairs or refurbishing.


why not recommended?
“rolling on West 107/207 epoxy (I’ve done it but don’t recommend it)”

I believe you meant to say 105/207, but why would you NOT recommend it?

I wouldn’'t recommend it because it is
a tedious process, and because in spite of scrupulous surface preparation, I had a bit of epoxy flake off one of the kayaks I resurfaced. This may apply mainly to whitewater boats, where the distortion of the hull is more likely to break the bond of the epoxy to the hull. But it’s an awful lot of work to have the resurfacing fail.

Thickness of the epoxy coating may be a factor, but I tried to roll on only 5 thin applications, hoping that there would be enough thickness for final sanding, and that the epoxy would be thin enough that it could flex with the hull.

Willing to take a Chance
For an old all carbon layup oc1, I just brushed on a coat of polyester resin instead of epoxy, and appears to be holding up quite well. Figured it wouldn’t bond, but, I guess the old finish was so old, it didn’t matter.

adhesion of resin
I had very good luck with West 105/207 and I have coated several hulls where the clear coat was abrading away too fast on a c/K cloth.

Surface preparation involved washing the hull, drying it, light sand to create a mechanical key, use acetone to remove any possible grease and then apply epoxy by brush. The temps were rather high and I had to mix several small batches to prevent an exothermic reaction (resin going hot) in my pot.

The 207 hardener has enough UV stabilizer for my applications (kayaks stored inside dark garage) and after 3 years is still holding up.

My prep was almost exactly the same.
Maybe I missed a spot, but the chip-out was in an area that takes a lot of light blows. If I had to do it again, I might have flamed the hull surface, as West’s data indicates that works better than sanding.

The hull surface was Kevlar in vinylester, hence the fuzzing. I did have to flame the fuzz to get it to collapse into little black balls that shaved off easier.


– Last Updated: Dec-09-11 2:16 PM EST –

The issue I have is a chalking appearance. I suppose I should have said the sun damage was to the gel coat rather than to the carbon fiber itself. This is an Epic V-10 surf ski.

Let me know how it works out.
I’m buying a used demo carbon Epic Touring Cruiser 16 soon, and it has a small area of milky looking clear coat.

Three solutions
Gelcoat oxidation manifests itself as a milky or chalky whiteness. It is actually caused by micro-pitting of the gelcoat. The micro-pitting causes reflected light to scatter, which dulls the original color and causes chalkiness.

The general fix is to get rid of the pitting, to make the gelcoat “level” again. There are three ways to do this.

  1. Scrape, abrade or buff the surface to flatten out the pits or make them less deep. This can work, but you are thinning the remaining gelcoat every time you do this. This solution requires a lot of time and effort unless you have power tools. At some point, especially with badly oxidized and repeatedly oxidized gelcoat, this solution will remove all the gelcoat. There are many, many rubbing and polishing compounds on the market, some of them quite expensive.

  2. Fill up the oxidation pits with some sort of “long term” clear coating such as resin or varnish. This won’t really be permanent and will add some weight. Also, the coating may or may not adhere properly.

  3. Fill up the oxidation pits temporarily with Penetrol, which you can buy for about $8 in a hardware store. This takes about 10 minutes to apply and wipe off. It slowly wears off, but looks good on my boats for at least one season.

    Methods 2 and 3 obviously don’t remove any of the remaining gelcoat.

    I gave up on method 1 after too many hours of manual rubbing and buffing every other year. Penetrol treatment is much less expensive and time consuming, and looks much better than my manual polishing and buffing efforts. I’ve never tried the resin/varnish solution on an entire hull.


And check out this thread with before and after pictures of it.

This might be exactly what you are looking for


Evershield looks pretty impressive.
Prepping the hull and the application of the stuff sounds like not so much fun.

Yes, that looks nice…
but I guess the Evershield will have to wait for a different project. I just picked up some Penetrol today. Wasn’t real easy to find in my local area. I finally found it in stock at Home Depot.

Yes, Evershield looks nice…
but I just picked up some Penetrol today. I’m going to give that a go.