: Gorilla Glue seems to have a shelf life once opened. Anybody have
: any way of stopping it from hardening in the bottle? Or does
: anyone know what the solvent is? Nothing seems to work.
: I guess once oxygen gets in there, it's just a matter of time.
: Lessons learned - only buy small bottles.

Urethane glues like Gorilla are activated by humidity. They don't have a solvent that evaporates or dries like water in white glue. Instead they rearrange themselves chemically as they cure. Humidity starts this chemical reaction, this is why they suggest you wet down one surface before gluing things with Gorilla glue.

If you use a bottle of glue on a day when the air is humid, any air sucked back into the bottle is probably enough to get the chemistry going. Use on drier days will probably result in a longer shelf life.