For whatever reason, the acceptability of bubble baths gets thrown out with the bath water as you get older. When you’re a child, it’s fine. When you’re an adult, it’s either considered unsanitary or childish. Well guess what bubble bath bashers? If you’re going to take a bath, a bubble bath is better, scientifically.
The question of bubble baths’ superiority was put to The Naked Scientists, which hinged on the insulating properties of the bubbles. If the bubbles can keep the bath warmer for longer — the argument goes — putting bubbles in a bath is always the better option.
According to the physics, the answer is clear: air is a wonderful insulator, and so a thick layer of air trapped inside soap should keep more heat in the tub for longer. The Naked Scientists confirmed this, though they noted that most of the heat lost during a bath isn’t through the interaction between water surface and air, but through the walls of the tub (cast iron tubs suffer especially).
One of the scientists even confirmed the assertion with an experiment. Filling two identical bowls with an identical amount of water, he measured the temperature over time for each, one covered with a layer of bubbles, one without suds. The results are below:
As you can see in the graph above, the water with the layer of bubbles lost less heat over time, almost 50 percent less. And because this small scale result should scale up, that means a bubble bath should stay hotter, longer. Superiority confirmed, because science.