The Volokh Conspiracy

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Volokh Conspiracy

The physics of drying your hands


Here's an interesting post from my friend and former classmate Doug Natelson, now a professor of physics and engineering at Rice University, on why some ways of drying your hands work better than others. The opening:

We've all been there: You wash your hands after using the restroom facilities, and turn away from the sink only to find one of those sad, completely ineffectual, old-style hot-air hand dryers bolted to the wall. . . Why do these things work so poorly compared to paper towels? What insight did Excel and Dyson have that makes their systems so much better?

It all comes down to the physics of trying to dry your hands.

The short answer is that using high pressure air to blow the water off your skin works much more effectively than using hot air to evaporate the water from your skin. For the longer version of the answer, check out the post.