How To Detect Kevlar Sun Damage

-- Last Updated: May-18-16 7:50 AM EST --

Anyone know how to detect Kevlar sun damage? My old and very used Sawyer Solo Kevlar cracks easily, i think this might be from years spent in the Florida sun and i read somewhere kevlar degrades fast under sunlight. The new kevlar repair patches i did are yellow, while the old original kevlar looks more this from sun damage? does color have anything to do with it?

i'm shopping for used canoes and kayaks, and wondering how you tell if the owner left it out in the sun to much.

My Wenonah Odyssey is 25 years old and brown. It was stored outside under snow one winter in Maine

Inside the rest of the time. So its UV exposure is pretty low.

I dont hence think color is a good judge.

brittle hulls
and alligators are incompatible.

Qiuestion and possible advice
Is the canoe a clear coat Kevlar?

If it is clear coat, instead of looking for a new canoe, why not just redo the whole bottom with West Systems epoxy?

I have a 20 year old one that I just redid the bottom for the second time.

If you do it right, it will be good for another five or six years or until you beat it up

Total cost for materials was $80.

It will cost you about $100 since you will probably need their metering pumps.

If you have never done it, I can walk you through the process.

Jack L

Sawyer gelcoat bottom+clearcoat topside

– Last Updated: May-18-16 5:14 PM EST –

I might do that. My old Sawyer solo has gel-coat bottom and clear-coat topside. Gel coat has many stress cracked areas that i've been sanding off and patching with glass, then sandwich a kevlar patch over the inside.

So its the sun effected clear-coat that turns the kevlar brown?

if i get really bored I might cut some fresh kevlar test sample (scraps) and throw them up onto my roof, one with epoxy clear coat and one without...then give them a "stress test" after a couple weeks (Florida sun, ha ha!) , then report back, sorry i know of no way to speed up the process other than a Florida summer

redo brittle degraded Kevlar with Gflex topcoat ?

try searching:

cboaters may use a specialized language form

Aramid naturally darkens with age
independent of the resin. Most epoxies become chalky when severely photodegraded.

If you leave a piece of dry aramid cloth in a ziplock bag and expose it to sunlight it will darken.

Darkening of aramid does not necessarily indicate it has become weakened or brittle.

The Kevlar doesn’t age with UV, the resin it’s laminated with does. Clear laminates have the least UV resistance, solid opaque colors (paint) have the most.

Unless it’s severely weakened it might be able to be re-coated with epoxy to help restore it’s strength. You never really know what resin was used to build the boat to start with and epoxy is compatible with any of them, the esters won’t stick to epoxy permanently.

Bill H.

Right but uncoated Kevlar DOES degrade
so i did a little more reading, turns out bare Kevlar DOES degrade from sunlight, not just the resin its coated with. i guess it makes sense as it is a polyamide similar to nylon…and if you’ve ever left nylon rope in the sun for a few months well you know how easy it will weaken/ break apart.

To save money/weight many canoes and some kayaks are not top-coated to protect the aramid fiber from the sun, something to consider when buying used in the sunbelt regions.

“Aramid fibres will degrade in Sunlight and high UV environment.

Carbon Fibre or glass are not very sensitive to UV radiation.

It is fairly irrelevant however because neither Kevlar, glass nor carbon fibre are often used on their own in boatbuilding applications. They are embedded in a matrix that often degrades in UV light. This is the case of epoxy resin which will go chalky and lose strength if allowed to remain in sunlight. Polyester and Vinylester resins are more resistant to UV exposure but are weaker than epoxy” -Christine DeMerchant