hawks, how thick did you apply it to your stones? SOC can be used to apply texture, and that would increase the drying time. It just sounds weird that you are reporting it as being sticky, though. It is supposed to be a great water barrier, but I don't know how well it would hold up in a constant flow of water like in a fountain.
If you haven't already, put it under a fan for a while and see if that helps.
If you haven't already, put it under a fan for a while and see if that helps.
