I don't know what other people are doing, but I just dry that section of rhizome as well as I can, apply glue to the rock, and press them together. It dries quickly, and then I put it in the tank.
You can do either. I just towel dry the rhizome and driftwood or rock and attach out of the water, but if the wood or rock are already in the tank and can't be removed then you can glue it underwater.
Wow, too cool! It never even occurred to me to try gluing underwater. I'm going to have to try it out soon!if the wood or rock are already in the tank and can't be removed then you can glue it underwater.
As stated earlier in this thread, if you are attaching underwater the glue will from a film that creates a bubble around the glue as soon as it comes in contact with the water. You have to press the rhizome hard enough against the wood or rock to burst the film or bubble and the glue then is in contact with both pieces and adhears.