I’m a bit absent minded. This morning in the kitchen, I absentmindedly grabbed with my bare hands a cake pan that had been heated in the oven to 450F(232C). I had forgotten that I had taken off my oven mitt. I grabbed the pan firmly and picked it up on one side. I should have been severely burned but I escaped because of the Leidenfrost effect.
The Leidenfrost effect is a phenomenon in which a liquid, in near contact with a mass significantly hotter than its boiling point, produces an insulating vapor layer which keeps that liquid from boiling rapidly. This is most commonly seen when cooking; one sprinkles drops of water in a skillet to gauge its temperature—if the skillet’s temperature is at or above the Leidenfrost point, the water skitters across the metal and takes longer to evaporate than it would in a skillet that is above boiling temperature, but below the temperature of the Leidenfrost point. It has also been used in some dangerous demonstrations, such as dipping a wet finger in molten lead and blowing out a mouthful of liquid nitrogen, both enacted without injury to the demonstrator. The effect is also responsible for the ability of liquid nitrogen to skitter across lab floors, collecting dust in the process.
I had taken my oven mitt off in order to scoop some batter out of a bowl with my bare hands. I washed my hand off and then, with it still wet, I turned around and picked up the very hot pan. I felt the water in contact with the pan turn to steam and bubble through the water close to my skin. It felt like sticking one’s finger into warm seltzer water. I felt no heat at all but realizing what had happened, I dropped the pan before the water evaporated and the heat of the pan could burn me.
Of course, without the water on my hand, I would have felt the heat of the pan and probably would not have grabbed it. Still, it’s a startling example of a very interesting natural phenomenon.