We will try to understand how Teflon coated non stick pans keeps food from sticking.
Nonstick pans are expected to last from 3 to 5 years with normal use. It also depends on how often the pan is used, the types of cooking done with the pan and the utensils used on the pan can all affect the lifespan of nonstick pans.
The discovery of first nonstick pans technology began with research on refrigerator. Scientists at the Kinetic Chemicals plant, were searching for a less toxic chemical to use as a new refrigerant.
An Ohio scientist, Roy Plunkett was part of this research team. In 1938, he set up a mixture meant to produce tetrafluoroethylene gas and left it overnight. The next morning, he found a white, waxy substance in place of the gas he had expected. After analysis, the new substance was found to be polytetrafluoroethylene, or PTFE, and was quickly recognized as an exceptionally slippery substance. The chemical was patented in 1941. Du pont trademarked this substance as Teflon in 1945. Plunkett was inducted into the National Inventors Hall of Fame for his invention of Teflon in 1985.
For us to understand why PTFE is a useful nonstick coating, we must study at its structure and properties. PTFE is a type of fluoropolymer. A polymer is a large molecule made up of smaller molecules of the same type. Fluoropolymers are polymers that combine the fluorine atom, which is the key to many of the unique characteristics of PTFE. Fluorine’s electron structure is very stable — it doesn’t share its electrons with other atoms easily.
It was not until Marc Gregoire, a French engineer, found a way to bond PTFE to aluminum that the first nonstick cookware was created. Marc Gregoire and his wife, Colette, started selling their cookware in France. In 1956, they founded the Tefal Corporation. The U.S. Food and Drug Administration (FDA) approved PTFE for food processing equipment in 1960. With this approval, Tefal, known as T-fal in the U.S., began selling its pans in the United States. Other manufacturers soon joined the market.
Think about a high school dance. The fluorine atoms are the governess, and the carbon atoms are the female students. Anything that might interact with the carbon is the male students. As governess, the fluorine atoms keep the boys away from interacting with the girls — in a frying pan, it keeps the food from sticking.
Along with their resistance to reacting with other chemicals, fluorine atoms also play a role in giving PTFE a low coefficient of friction. The coefficient of friction is a measurement of how easy it is for two substances to slide by each other — the harder it is to slide, the higher the coefficient of friction. PTFE doesn’t put up a lot of resistance when sliding by another substance, giving it a low coefficient of friction. The low coefficient of friction gives PTFE that signature slippery quality.
To prevent scuffs and scratches on the nonstick surface on a pan, utensils made of wood, plastic or coated materials are the best choices. It’s also a good idea to store the pan in a cabinet or area where it won’t get scratched
There are many variations of the process to melt the nonstick coating onto the cookware’s metal surface. Basically, they all start with the metal base, or substrate, which is created in the shape of the desired cookware. Most nonstick cookware is made of aluminum, but other metals, such as stainless steel, are also used.
The next part of the process deals with applying the nonstick coating to the pan substrate. According to DuPont technology manager William Raiford, there are two ways to overcome the nonstick problem — mechanically and chemically.
Let’s go back to the example of the dance. The governess keep the female students from interacting with the male students. To distract the governess, a male student might enlist a friend to create a disturbance on the other side of the room, causing all the governesses to move in that direction. Another tactic might be to build some common relation among the governess and students by playing some music from the governess era and getting everyone onto the dance floor together. Either way, the male dancers have a chance to dance with the females.
When making nonstick cookware, the manufacturing version of the male students’ disturbance starts with roughening the surface of the substrate. This makes it easier for PTFE’s fluorine molecules to stick to the surface. Some methods include roughing the surface with molten metal or chemicals.
The common ground is a primer or base coat, which has a special formulation that allows it to adhere to both the metal substrate and several nonstick coating layers. The number of PTFE-based coatings, which are either sprayed or rolled onto the surface, depends on the type of pan.
According to Raiford, this process can include heating between each layer, or the layers can be put on top of each other while they are still wet. The final step is sintering. “This is a high temperature bake usually at around 800 degrees Fahrenheit for about 3 to 5 minutes, that’s about 427 degrees Celsius. This dries and cures the polymer and also helps to lock it to the metal.
This coating keeps everything from eggs to meatloaf from sticking to your pans — but you can’t scrub away at it like you can with some cookware. Next, we’ll look at how to keep the nonstick finish on your pans pristine.