G-flex on G-flex Question

Any need to wash down the g-flex like you have to wash between coats of other West System epoxies?

I just want to fill in a little more along a v-groove I carved on top of a crack in the vinyl gunwale. I laid g-flex in the groove and it slumped before it set. I suppose I need to rough it up, but I don’t want to. Just a little fill.


I don’t think so
I have applied multiple thin coats of G-Flex on top of each other, as when filling in a void and fairing a damaged hull, many times with no surface preparation and had no problem.

If it has been several days I might wipe the surface with some isopropyl or denatured alcohol first to remove any surface dirt.

Yes, wash needed

When patching up my Cascade, I had to apply several layers of G-Flex. I called West System for advice and theirs was if the base layer of G-Flex has cured you need to wash it - pretty sure a water wash was all that was needed.

They were very helpful - they even have a person knowledgeable about paddle craft repairs.


I’d think it gives off amine blush …

– Last Updated: Mar-29-12 10:01 AM EST –

..... like other expoxies , so wash it and give it a little mech. surface bond w/sand paper , can't hurt to be safe .

I haven't tried the G-Flex yet but it's a 1-1 isn't it ?? Every 1-1 I've used does give off amine so far , and you know unattended to amine causes delam .

West 207 cat. gives off no amine , but I still wash and prep. it before each additional coat , know what I mean ?? ...

It does mix one-to-one. Most of the time I have applied multiple coats with no surface prep the epoxy was not fully cured and there was no problem.

The other times I had usually wet sanded the surface and then rinsed and dried it, so it was washed by default.

Sanded, washed, wiped
Right. Why take chances?

I sanded, washed with soap and water, wiped with alcohol, and filled the low spots with gflex. I mixed the smallest drops I could squeeze from the gflex bottles and tooth-pick ladelled onto the low spots on the gunwale-crack repair. After overnight repair, I just looked at the result, and I am pleased.

Now, the question is, assuming the repair holds, is the repair going to be stronger than the rest of the 36-year old vinyl gunwales. None of the four cracks I patched were all the way across the gunwale. three of them had not even spread to the top side of the gunwale and I only discovered them when I brought the boat into the shop. So, I am hopeful.

Thanks for the advice.


I have patched about 6 gunwales
with G Flex. For the typical black plastic or vinyl gunwales mixing graphite powder in the epoxy results in a more cosmetic repair.

Some are now about a year out. They seem to be holding up fine.

Most recently, I cracked a piece of the outer plastic gunwale off of my Viper 11 when I flipped it over and the side hit a tree. I fit a little piece of minicel foam into the open part of the gunwale to serve as backing for the epoxy and put a layer of epoxy on before fitting the plastic piece back in, then later put another thin layer of G Flex/graphite powder over the top of the repair. I suspect this portion of the gunwale is stronger than the rest.

I have done something similar when repairing plastic gunwales in which thwart and seat screws were overtightened and broke through the gunwale top. I later drilled holes through the repaired area and remounted the machine screws at the same location and this has held up well.