G Flex epoxy

What do you use to thicken G Flex? Useing it to repair some plastic parts and by the time it sets up, it spreads out too thin to have much strength. It’s still very tacky after sitting for two hours. Any way to speed up the cureing process?

I have used
The standard thickening agent sold at West Marine. As far as faster cure times… you could switch to the 5-Minute flavor.

I usually use colloidal silica powder
WEST Systems 406 otherwise known as Cab-o-sil:


WEST also has a higher density filler (404) which is a mixture of calcium metasilicate and cab-o-sil which I haven’t used.

The silica powder will change the color of the G-Flex from a translucent honey color to an opaque creamy color depending on how much you add.

I have also used WEST 423 Graphite powder which will make the G-Flex an opaque gloss black color. This doesn’t thicken the epoxy to quite the same extent.

You can carefully warm the epoxy with a heat gun to accelerate the cure time, but warming it also decreases the viscosity so if you do this you might want to use even more thickening agent.

I have never seen a 5 minute epoxy
with the superior bonding qualities of G-flex, or even West 105/205. The 205 hardener gives fast setting in summer conditions.

good point
The OP could go for the 655-K G/flex Thickened Epoxy Adhesive Repair Kit

I would go for the 650-K kit
The 650-K kit has a goodly amount of colloidal silica powder included allowing one to thicken the epoxy as much as desired.

Ditto on Colloidal Silica

Didn’t West also market G-flex in a pre-
thickened form, for people who can’t decide on their own?

That is the 655-K kit: