They use a special chemical bond, some sort of glue or heat treatment, on the reverse side.

From Discovery.com Nothing sticks to Teflon, so how does Teflon stick to the pan? Before we dive into that, let's dispense with a technicality: Teflon was DuPont's original brand name for what now goes by various unattractive pseudonyms, such as "non-stick coated aluminum cookware," as well as a poetic variety of brand names. I'll call these slippery coatings "non-sticks." In the early days, what the non-stick stuck to was a mechanical issue. . Manufacturers textured a pan by blasting its surface with grit, gouging little pits in the aluminum, or by spraying the cookware with a micro-lumpy ceramic coating or stainless steel, which formed mini-mountains as it hardened. These textures gave the long, slippery non-stick molecules much more to brace themselves against. And when the non-stick wore off the peaks of the mini-mountains and micro-lumps there was still enough clinging to the slopes and valleys to keep the flapjacks flipping. Sort of. Trouble was these methods didn't hold up very well under normal household use, leading to a chorus of feminine voices across America, singing out in harmony, "TOUCH THAT FORK TO THAT PAN AND YOU'RE A DEAD MAN." (To the credit of these women, of whom my grandmother is one, their 1964-vintage Teflon still appears virginal, while I have forked to death a long, sad series of pans.) The bottom line was that the non-stick didn't stick to the pan long enough. So, back to the drawing board. . The basic non-stick molecule is a polymer, or chain, of fluorine atoms and additives such as carbon and hydrogen. The longer this chain, the tougher it is; but a molecule that's too long gets viscous and hard to handle. To move beyond mere mechanics, the frying-pan engineers added a sticky molecule to the non-stick molecule. Non-stick was now applied in coats, with the bottom coat containing the sticky additive that held to both the metal pan and the non-stick molecules. A coat of non-sticky non-stick went over that, non-stick and non-stick clinging together lovingly. A final non-stick layer, spiked with teensy bits of ceramic or other tougheners, protected the softer guts. This is how lots of non-sticks are made still: Grit-blast the pan; spray on a sticky primer coat, a midcoat, and a tougher top coat; and bake. Oh, yeah: Add colors if you like -- the fluoropolymer is naturally white, but cooks prefer somber saucepans. You may also add a handful of mica, a sparkly rock, to glimmer up the finish. But the latest non-stick revolution, probably lost on cooks, is a non-mechanical means of sticking non-stick to aluminum. In this method, which DuPont calls "smooth technology," new-and-improved sticky molecules in the primer coat sink as the pan bakes and chemically lock themselves to smooth, unmolested metal. The upper layers fuse together better, and you get a tougher pan. But even tough non-stick isn't very tough. . Each of the three coats is only about one one-thousandth of an inch thick, for starters. And non-stick softens as it heats, leaving forks as lethal as ever. Plus, raw non-stick is baked on at only about 800 degrees for four or five minutes, so you can toast it if you leave it on the burner with nothing in the pan. Then a rubber spatula, even in the hands of the gentlest grandmother, will slowly disentangle the long, slippery molecules and carry them away. Which raises the question: Are there health consequences to ingesting all those non-stick molecules? Not to worry, says DuPont's Kris Mohan: We are, after all, talking non-stick. "It's completely inert, and it passes right through the body without interfering with anything." http://www.discovery.com/area/skinnyon/skinnyon970606/skinny1.html