Teflon: The trick behind the enduring nonstick coating

By Lim Tri Santosa

BANDUNG (JP): Everyone is familiar with Teflon, that non-stick surface no self-respecting housewife can do without. It was discovered by accident by Dr. Roy J. Plunkett in 1938 at DuPont's Jackson Laboratory in New Jersey. Even though it was discovered in 1938, it wasn't used commercially until 1946, and even then, it was only used in industrial applications.

It turned out that Teflon was extremely difficult to work with. Known to science as polytetrafluoroethylene (PTFE), Teflon is inert to virtually all chemicals and is considered the most slippery material in existence. These properties have made it one of the most valuable and versatile materials ever invented. Teflon is slippery and impervious to most corrosive chemicals.

In 1941, when the United States was building the atomic bomb, scientists developed a method to separate two isotopes of uranium. This was accomplished with uranium hexaflouride, a highly reactive chemical. The U.S. government needed something that could coat the insides of tubes and gaskets that would not be eaten away by the uranium hexaflouride. Teflon's properties seemed perfect.

With the funding of the U.S. government, the difficulties of working with Teflon were overcome. That's the history, as DuPont registered the trademark, it has become a familiar household name, recognized worldwide for the superior non-stick properties associated with its use as a coating on cookware and as a soil and stain repellent for fabrics and textile products.

It's so inert that nothing sticks to it; to stick, it would have to react in some way. So how does it stick onto the surface of a frying pan? Teflon is made up of only carbon and fluorine atoms, it is called a fluorocarbon. This is what gives it its amazing non-stick properties.

Fluorine, due to certain electrochemical properties (you'll thank me for not explaining now), bonds so tightly with the carbon in Teflon that it's virtually impossible for other substances, e.g., scrambled egg, to get a chemical-type grip or a mechanical-type grip.

Chemical attraction

You see, oils and fats have no chemical attraction to fluorocarbons. This is why most foods don't stick to Teflon pans. In early days, the Teflon was pressed onto the metal surface after the metal had been "roughed up" by abrasion and coated with a primer chemical with lots of microscopic cavities.

The Teflon squeezed into the cavities and stuck to the pan by sheer mechanical strength. But those early frying pans didn't keep their coating very long, because Teflon is so inert that its long molecules slither like wet spaghetti, and it often came loose from the mechanical primer.

In the end, these methods didn't hold up very well in everyday use. If you used a metal utensil on the non-stick surface you would carve off a strip of Teflon with ease. In order to save some cooking pans and a few marriages, the scientist went back to the drawing board to design a better method. So how do they get Teflon to stick to the pan now?

First, they sandblast the pan to create a lot of microscratches on its surface. Then they spray on a coat of Teflon primer. This primer, like most primers, is thin, enabling it to flow into the microscratches. The primer surface is then baked at high heat to get a reasonably secure mechanical grip. It is a sticky additive that grabs both metal pan and non-stick molecules. Then there's a second layer of PTFE non-stick that clings to the sticky first layer, and finally the topcoat is a clear PTFE that sticks to the PTFE particles of the midcoat layer. Got all of that?

Non-stick performance and durability are determined by the pan's thickness and the quality of non-stick coating. Overheating and utensil abrasion are the two factors that most affect non- stick durability. A superior thick coating on a thin pan makes no sense, as the pan will overheat easily. The resulting "hot spots" will damage even the best non-stick coating. Therefore, pan thickness is essential to non-stick longevity.

Teflon coatings still aren't perfect. Even though it's designed for high heat, it still gets soft when heated to extremely high temperature.

Additionally, if you leave an empty non-stick pan on a hot burner too long, you can roast the surface. This causes the bonds between some of the carbon atoms to break, giving other undesirable stuff a chance to bond. Teflon coatings that wear off cannot be repaired at home. They would have to be re-coated at very high temperatures in factory processes, which is not economical to do on a single pan.

Tip: Cleaning non-stick cookware

Mix one tablespoon of baking soda (Sodium Bicarbonate) and an adequate liquid dish soap with water (enough solution in these proportions to about half fill the pan). Simmer this solution for five minutes in the stained pan.

Be careful, the solution will foam and if it boils over, it may stain the outside of the pan. Remove from heat and check the pan surface. If the stain still remains, repeat the treatment.

This solution is a strong oxidizing agent and will cause some change in the color of Teflon becoming lighter (No wonder, it is used as whitener in toothpaste).

This bleaching effect does not reduce the non-stick performance of the pan. After the cleaning/stain removing treatment, thoroughly wash and dry the pan; then wipe it with cooking oil to condition before using it again.