It's been slipped into everything from frying pans to space suits to the nation's political vernacular, and now Teflon, still the slickest solid on Earth, is sliding into its second half-century.

Discovered accidentally April 6, 1938, by a young chemist named Roy J. Plunkett, the waxy white plastic turns 50 this week, still dominating dozens of scientific and consumer uses with no hint of a higher-tech replacement.It keeps the eggs from sticking to frying pans for sure. But it also coats electrical wires, chemical tanks, jogging suits and lightbulbs. It's used to patch human hearts. It keeps the Statue of Liberty from rusting.

"The applications, as far as I can tell, are no smaller than our imaginations," says Plunkett, now a septuagenarian retiree from the Du Pont chemical company. "I'm amazed at the impact. And there's more to go."

The reason for Teflon's endurance is simple: Nothing else is so slippery, so tough and such a good insulator, all at the same time. Even after five decades, "It is unique in these qualities," says professor Fred McGarry, a specialist in such materials at the Massachusetts Institute of Technology.

It's a discovery that almost slipped away. Plunkett, two years out of college, was working with refrigeration gases in a Du Pont lab in Deepwater, N.J., when an assistant pulled a cylinder of Freon out of a dry ice storage bin, turned it on --and nothing came out.

Someone else might have assumed the cylinder had leaked and tossed it away. Plunkett didn't. He weighed the cylinder. He shook it. He cut it open.

"A white solid material was obtained, which was supposed to be a polymerized product" of the Freon compound, Plunkett recorded laconically in his lab notebook entry of 4-6-38.

Voila.

"People describe it as a lucky chance, a bit of serendipity or a flash of brilliance," says Plunkett, an inductee into the National Inventors Hall of Fame. "I like to think of it as a combination of all three."

Du Pont testers gradually established Teflon's extraordinary properties. It is "nearly inert," says McGarry; it won't react with chemicals or break down in the environment.