Recently at a thrift shop, I bought a lovely 8-inch stainless steel skillet. When we cook eggs, we like the whites to be done, but the yolks runny enough to soak into a piece of toast.

Our expensive nonstick skillet had lost its no-stick ability, so I hoped this new frying pan would mark our return to perfectly cooked eggs. To my dismay, it was no better than our old pan. The eggs stuck and were mangled when I tried to remove them. An Internet search for “eggs on stainless steel” caused me to face-palm myself. The answer was the Leidenfrost Effect. I had written a column about it ten years ago.

The Leidenfrost Effect is something many grandmas tested for, even though they might not have known the technical name for it. You let the skillet heat up, then add a drop of water. If the droplet instantly boils away to nothing, the skillet isn’t hot enough. However, if the droplet forms into a ball and skitters about as if dancing on the hot surface, it’s time to add the eggs or pancakes or whatever.

Here’s why. When a pan is around 379 degrees F, the bottom of a water droplet flashes into steam and forms an insulating layer between the hot surface and the droplet. The droplet dances about on that layer of steam. Little by little as the steam barrier is lost, it is replaced by water from the droplet. Eventually, the last bit of water turns to steam and the droplet disappears.

If oil is added to the pan, the oil will experience the same effect. Instead of sizzling as in a fryer, an insulating layer of steam will be created between the oil and the surface. Eggs (or most anything else) put in the pan will not stick, but will slide happily about just like the droplet did.

Should a surface get too hot, the Leidenfrost Effect goes away, but it’s more likely to fail because a pan is too cool rather than too hot.

Also, if oil is added too early, it will simply heat up along with the pan and there will be no Leidenfrost Effect. Heat the pan, then add the oil.

Our expensive non-stick skillet had depended on a super-slick surface, not on the Leidenfrost Effect. Because of its nonstick coating, I’d stopped testing for—and even forgot about—the Leidenfrost Effect. When that coating eventually wore away, so, of course, did the pan’s nonstick ability. I was considering the purchase of a new pan when I found the stainless steel one at a great price.

I tried a second time to cook eggs in the steel skillet, this time doing the water droplet test to assure proper temperature. Voila, perfection. I tried the same procedure with our former, now not-so-slick fry pan. Same excellent result.

In 1756, Johann Gottlob Leidenfrost published a work describing the effect that now bears his name. I forgot his discovery once. I won’t forget it a second time.