A client requested a bathtub which would keep the water hot, without noisy jets or fancy equipment.
Someone mentioned Kaldewei, a German tub maker. I chatted with the US rep for a while discussing our needs. Two days later a sample of Kaldewei signature steel enamel arrived along with some literature.
Tonight I am conducting a test. I submerged the sample in hot water, the sample got hot immediately. It took 15 minutes to cool completely. I have had it half way submerged for about half an hour now and both the water and the steel enamel are still warm. I think what is really nice about it is the fact that the part that is above the water is equally warm.