Are you sure about that? 16-21C? All epoxy would harden in the can.

Chris wrote:
Are you sure about that? 16-21C? All epoxy would harden in the can.

Epoxy cannot harden if it's not mixed. The resin may crystalize over
time, but it can be "rejuvenated" by heating it until it turns back to a
clear liquid.

Polyester resin WILL eventually cure without being mixed with hardener,
which is actually a catalyst, not a structural/chemical component of the
final product.

Chris wrote:
Are you sure about that? 16-21C? All epoxy would harden in the can.

He is right though - when mixed, it certainly canharden in the can -
the trick is to have as big a surface when you have mixed it as
possible, thushave as long an opening time as possible.

The 16-21 degrees is for a "full strength" cure.

Dane:

Epoxy doesen't set off at room temperature without harder.
Hardener is not acting as a solvent.
Heat is never a catalyst.
The hardening of resin is always a chemical reaction.

And yes, when mixed with hardener, all resins will cure.