Durability of Kevlar
 

Kevar, as used in kayaks and canoes is arimid cloth, not resin.
There preferred resin systems are epoxy or vinylester.

We built 8 kayaks, vacuum bagged, with 1 layer of kevlar on the
inside, and 5 layers s-glass outside. They had selective extra
layers, of kevlar, in high impact areas, such as under the seat and in
the ends. They were Lettman Mark IV designs and my finished boat
weighs 25 lbs. This boat is 20 years old and I still use it for
overnights. By todays standards, this is a huge boat.

We used Vinylester, supplied by CKS, Dupont 8084.5, I think (1983).
My boat held up fine for about three years and then starting cracking
when hitting rocks. A friends boat, built the same way, but with
epoxy, lasted much longer. I think the resin continues to cure, and
eventually gets brittle, epoxy being the better of the two.

The main damage, in kevlar boats, is delamination from impact. The
material is very strong. None of the damaged areas in my kayak has
gone through the material, all are delamination.
Epoxy is by far the better patch resin. The promoted VE resin goes off
in the can, after a period of time, thus does not store well. Epoxy
has a very long shelf life.
Dan


On Thu, 28 Aug 2003 11:28:49 GMT, "Bob Burns"
wrote:

Thanks to you all for a good discussion. But please, can someone clear up a
little confusion? Kevlar is polyaramid resin. I thought Kevlar canoes (I
have one) are made of Kevlar and fiberglass. Is that not true? Also, is
there a quick and easy way to fill scratches?

Colorado Springs, CO
My advice may be worth what you paid for it.