Yeah, I recall as a kid it was easy to scald or burn oneself on an exposed rubber bottle, and of course it cooled much more rapidly (I too remember that cold cl

Yeah, I recall as a kid it was easy to scald or burn oneself on an exposed rubber bottle, and of course it cooled much more rapidly (I too remember that cold clammy feeling in the morning). However, the more usual situation was to put the HWB in a knitted woollen jacket. That kept the heat in and it didn't burn one and was still warm in the morning.