I just adore this guy's columns. You might have some attachment to this one.
Stuck on Nonstick
By Robert L. Wolke
Wednesday, April 3, 2002; Page F01
I want to buy a good nonstick saute pan, but I'm bewildered by the number of brands and types out there. Can you help me sort them out?
I'll try. Our contemporary American society produces a dizzying profusion of brands and models of virtually every consumer good. I once counted almost 100 brands, types and sizes of toothpaste packages on the shelves of a drugstore. Sometimes, I almost wish I lived in the former Soviet Union, where there was but one brand of everything. Glorious Workers' Revolution Tooth Cleaner, perhaps.
The primary cooking characteristics of saute pans, or frying pans, depend on their thickness and the metal or metals they are made of. There are pans made of copper, aluminum, stainless steel and sandwiches of these metals intended to create the best combination. But that's another column. You still have to decide whether you want a nonstick surface or not, because many pans come in both versions.
First, what is this stickiness that we so zealously want to prevent ?
Two substances may stick to each other for reasons that are primarily either physical or chemical. Although there are weak chemical attractions between protein molecules and metals, the sticking of an egg to a regular frying pan, for example, is largely physical; the congealing egg white grabs onto microscopic crags and crevices in the pan's surface. A shiny new stainless-steel frying pan will stick more and more as it develops scratches from use.
To minimize physical sticking we use cooking oil. It fills in the crevices and floats the egg above the crags on a thin layer of liquid. Any liquid would do that, of course, but water wouldn't last long enough in a hot pan to do much good unless you use lots of it, in which case you've got yourself a poached egg instead of a fried one.
The surfaces of nonstick pan coatings, on the other hand, are extremely smooth on a microscopic scale, so there's nothing for food to grab onto. Of course, glass and many plastics share this virtue, but the nonstick coatings are very thin and can withstand high temperatures.
The Teflon Inventor
Chemical sticking is also important. At high temperatures, foods generate a hodgepodge of reaction products that have molecular attractions to metals, and the food therefore sticks. Enter: Teflon.
In 1938, a chemist at the E.I. DuPont de Nemours Corp. named Roy Plunkett (writers love to include his name; he wouldn't be nearly as famous if it had been Jones) concocted a brand-new chemical that chemists call polytetrafluoroethylene, nicknamed PTFE and trademarked by DuPont as Teflon. It is remarkably smooth and nothing, including super glue, will stick to it. It began to show up in the kitchen in the 1960s as a coating for frying pans that would clean up in a jiffy because they didn't get dirty in the first place.
Modern versions of PTFE-based coatings are vastly superior in performance to the early ones, and are known by a variety of trade names, including DuPont's Silverstone. The coatings are applied by means of various schemes designed to make them stick to the pan, which as you can imagine is no small trick. I'll get to that.
What's special about PTFE is that its molecules just won't form chemical bonds to anything. They are made up of only two kinds of atoms, carbon and fluorine, in a ratio of four fluorine atoms to every two carbon atoms. Thousands of these six-atom molecules are bonded together into gigantically bigger molecules (polymers) that look like long carbon backbones with fluorine atoms bristling out like the spikes on a woolly caterpillar.
Of all types of atoms, fluorine is the one that least wants to react with anything else once it has comfortably bonded with a carbon atom. PTFE's bristling fluorine atoms therefore effectively constitute a suit of chemical armor, protecting the carbon atoms from bonding with any other atoms that may come along. PTFE won't even let most liquids, whether oily or watery, adhere to it strongly enough to wet it. Put a few drops of water or oil on a PTFE-coated pan and you'll see.
Making Nonstick Stick
So how do they get this nonstick coating to stick to the pan in the first place? One method is to spray the pan first with a base coat of PTFE blended with a material that does stick to metal, and then to spray on subsequent layers with increasing proportions of PTFE until the top coat is virtually pure PTFE. Early Teflon nonstick cookware contained only one or two coats that scratched or flaked off easily. (Because PTFE is so nonreactive, it is also completely nontoxic; any swallowed fragments of it would sail right through the digestive tract unchanged.) The best PTFE-based cookware today has up to seven coats of graded materials.
Another coating method, trademarked Excalibur by Whitford Corp., is used on several brands of quality cookware. In this process, tiny droplets of white-hot, molten stainless steel are blasted onto the surface of the pan. The droplets splatter and weld themselves onto the pan, leaving a jagged, toothy surface. Several layers of PTFE-based formulations are then sprayed on, building up a thick, strong coating that is held tightly by those microscopic steel teeth. This is an example of a "reinforced" nonstick coating, in which deliberately created irregularities in the metal's surface play a role in making the nonstick coating adhere.
Unfortunately, PTFE is soft and scratches rather easily, although many manufacturers today are daring us to use metallic utensils on their improved formulations. (I still won't do it.) Another drawback of PTFE-based coatings is that at temperatures above about 530 degrees Fahrenheit they begin to decompose, giving off mildly toxic fumes. But a pan will almost never get that hot with food in it; just don't preheat it empty for longer than about three minutes. Reportedly, the fumes are especially perilous to pet birds. As one account puts it, their first clinical symptom is "sudden death." (I wonder what the subsequent symptoms are.)
Anodized Aluminum
There is another way to make aluminum cookware stick-resistant, if not actually nonstick: anodizing it. The manufacturer passes an electric current between the aluminum pan (the anode) and another electrode (the cathode) in a sulfuric acid bath. A layer of dense, hard aluminum oxide is built up, augmenting the thin, natural layer of oxide that ordinarily keeps aluminum from rusting. The aluminum oxide layer, normally white or colorless but blackened by a dye in the acid bath, serves both to harden the surface -- it's 30 percent harder than stainless steel -- and to protect it from acids, although the oxide is susceptible to highly alkaline chemicals such as dishwashing detergent. Other than that, aluminum oxide is quite unreactive, and it therefore resists sticking to other substances. Calphalon is one popular brand of anodized aluminum cookware. Most brands will say "hard anodized" somewhere on the pan.
A Hard Act to Follow
The newest high-tech wrinkle in nonstickiness is a coating called ceramic-titanium, developed in Denmark and used on Scanpan cookware. A mixture of titanium and a ceramic, so hot (30,000 degrees) that their atoms are broken down into a cloud of charged particles (Techspeak: a plasma), is fired at supersonic speed at the surface of an aluminum pan, where it anchors itself right into the metal, making an extremely hard, unscratchable surface. (Titanium is three or four times harder than stainless steel and ceramics are almost as hard as diamonds.) The actual nonstick material lies in microscopic craters in that surface, protected by the ultra-hard crater rims. According to the manufacturer, you can scrape it with steel implements to your heart's content, and all you'll do is wear down the implements.
Another relatively new brand that depends on surface hardness to resist (not prevent) sticking is Sitram. Its trick is to bond a shiny layer of extra-hard steel alloy onto a stainless-steel surface. The theory is that if it can't be scratched by ordinary steel, it will stay shiny and stick-resistant.
When Not to Use Nonstick
Nonstick saute pans of any kind have their limitations. Because of heat-induced decomposition, the nonstick property of PTFE degenerates over time. Reinforced coatings lose their nonstickiness more gradually, but don't expect any nonstick surface to last forever.
Nonstick pans generally don't brown foods as well as if the food were in direct contact with metal. That's because the browning reactions take place only at very high temperatures, and the coatings, whether PTFE or anodized, are poor conductors of heat compared with metals. Reinforced coatings are better in this respect because the roughened metal's ridges conduct heat farther up through the coating toward the food.
Finally, if you intend to make a sauce in the pan by deglazing the flavorful brown bits (fond in French) with wine or another liquid after sauteing a cut of meat, don't use a nonstick pan. All the fond will stick to the meat instead of the pan, and you'll have nothing to deglaze.
Sticking isn't all bad.
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