> My (unscienftic) choice is water that is very warm, but not hot. I
> think it works out to about 125 f. I was taught that about 100 was
> the way to go, but since I don't like soaks that go on for hours, I use
> warmer (but not too hot - that will ruin the sizing) water.>
In other words, scientifically speaking, it all depends.
One other thought, though -- I tend to have several fairly large trays
going at a time. In winter, hot water in the trays would help heat,
humidify the room. In summer..... this is less desirable.