As for leaving a horse in a wet rug overnight, any drying-off type rug, will be dry by morning if you leave a damp (not soaking) horse in it overnight to finish off drying. I have done it quite often. The whole idea of a thermatex is that it will wick the moisture from the horse to the outside of the rug, and you quite often see droplets on the surface as it is working. Now think about it: warm horse underneath = moisture then evaporating.