TODAY'S the day a half century ago that a scientist in New Jersey wanted to know why a cylinder loaded with stuff they call Freon wouldn't squirt on demand. What was the reason? Pulled from a freezer cooled with dry ice, others might have pitched it without thinking twice. But not Roy Plunkett, who worked for Du Pont. This was curious enough to warrant some thought. He weighed it. He shook it. Wide open he cut it to find lumped inside a ``polymerized product'' that has proved a boon to millions of those who get stuck with the dishes or need watertight clothes. They called the stuff Teflon, and no solid they say is slicker than it to this very day. You can heat it and stretch it and still it holds up. Even in space it shows the right stuff. But back here on Earth is where we best know it, thanks first to the French, who decided to market a line of cookware whose makers could boast ``an easier clean no matter how burnt the roast.'' Later a crafty wirecoater, named Gore, found that when stretched the stuff has small pores that let water vapor out while still fending off drops. Voil`a! Waterproof togs that ``breathe'' for joggers and tots. And for those who put politics high on the menu, you can credit Pat Schroeder for shifting the venue of Teflon from kitchen and closet to D.C., where was born the Teflon presidency. Early one morning, 'twas the summer of '83, the congresswoman was frying some eggs and said, ``See how these eggs slip the pan with merely a flick? Reagan's just like this pan. Nothing sticks!'' But for our money we still like it best when we're up to our elbows or up to our chests in dishes and soapsuds and crumbling sponges as we struggle to rid the kitchen of grunges. So thanks, Mr. Plunkett, for cracking the case of the Freon-turned-glop. It's helping us face our duties as householder with head held high. May its next 50 years help us stay clean and dry.