Don't worry, it's not as drastic as the thread title makes it out to be.
When I take my underfloor pipes off to replace them for stainless steel I'd like to take the opportunity to paint under there entirely with underbody seal. Everywhere. Obviously though this takes time to dry and thus the connecting coolant hoses will be left with nothing attached for an extended period of time before the new pipes go on.
My question is this; is it safe to do so? Will the minute amount of coolant left in the system simply dribble out and/or evaporate or will it dry out and leave a sticky mess that I'd have to flush? If it'll leave a sticky mess I'll just spray waxoil before fitting the new pipes, but I'd rather do the job properly with seal.