Food Science Fact
"To prevent sticking: heat a smooth non-stick the pan first, the metal will expand, filling any holes or irregularities in the pan, then add the fat (butter, or whatever fat you prefer). The pan should be very warm, but not too hot or the eggs will brown upon hitting the surface.
Gentle heating combined with gentle treatment is the secret when cooking any proteins, especially eggs, when eggs (or any protein) are overheated their protein bonds tighten and squeeze out the moisture, resulting in dry leathery eggs.”
—Corriher, Shirley O., biochemist and food science author, Cookwise, The Hows and Whys of Successful Cooking, pub. William Morrow, (1997) p.205