A non-stick surface is a surface engineered to reduce the ability of other materials to stick to it. Non-stick cookware is a common application, where the non-stick coating allows food to brown without sticking to the pan. Non-stick is often used to refer to surfaces coated with polytetrafluoroethylene (PTFE), which is sold under the brand name "Teflon." In recent years, however, other coatings have been marketed as non-stick, such as anodized aluminium, ceramics, silicone, enameled cast iron, and seasoned cast iron.
The Mycenaean Greeks might have used non-stick pans to make bread more than 3,000 years ago. Mycenaean ceramic griddles had one smooth side and one side covered with tiny holes. The bread was probably placed on the side with the holes, since the dough tended to stick when cooked on the smooth side of the pan. The holes seemed to be an ancient non-sticking technology, ensuring that oil spread evenly over the griddle.
The modern non-stick pans were made using a coating of Teflon (polytetrafluoroethylene or PTFE). PTFE was invented serendipitously by Roy Plunkett in 1938, while working for a joint venture of the DuPont company. The substance was found to have several unique properties, including very good corrosion resistance and the lowest coefficient of friction of any substance yet manufactured. PTFE was used first to make seals resistant to the uranium hexafluoride gas used in the Manhattan Project during World War II and was regarded as a military secret. Dupont registered the Teflon trademark in 1944 and soon began planning for post-war commercial use of the new product.
By 1951 Dupont had developed applications for Teflon in commercial bread and cookie-making; however the company avoided the market for consumer cookware due to potential problems associated with release of toxic gases if stove-top pans were overheated in inadequately ventilated spaces. Marc Grégoire, a French engineer, had begun coating his fishing gear with Teflon to prevent tangles. His wife Colette suggested using the same method to coat her cooking pans. The idea was successful and a French patent was granted for the process in 1954. The Tefal company was formed in 1956 to manufacture non-stick pans.
Not all modern non-stick pans use Teflon; other non-stick coatings have become available. For example, a mixture of titanium and ceramic can be sandblasted onto the pan surface, and then fired to 2,000 °C (3,630 °F).
PTFE and similar compounds
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer used in various applications including non-stick coatings. Non-stick coating systems often include a special treatment of the substrate. For example, Whitford Corporation's Excalibur consists of three layers of PTFE over a metallic substrate which is first grit-blasted to roughen it, then electric-arc sprayed with a proprietary stainless steel alloy. According to Whitford, the irregular surface promotes adhesion of the PTFE and also resists abrasion of the PTFE.
When pans are overheated beyond approximately 350 °C (660 °F) the PTFE coating begins to dissociate, releasing byproducts (PFOA) which can cause polymer fume fever in humans and can be lethal to birds. Concerns have been raised over the possible negative effects of using PTFE-coated cooking pans.
Processing of PTFE in the past used to include Perfluorooctanoic acid (PFOA) as an emulsifier, however PFOA is a persistent organic pollutant and poses both environmental and health concerns, and is now being phased out of use in PTFE processing.
Uses and limitations
With other types of pans, some oil or fat is required to prevent hot food from sticking to the pan's surface. Food does not have the same tendency to stick to a non-stick surface; pans can be used with less, or no, oil, and are easier to clean, as residues do not stick to the surface.
Utensils used with PTFE-coated pans can scratch the coating, if the utensils are harder than the coating; this can be prevented by using non-metallic (usually plastic or wood) cooking tools.
According to writer Tony Polombo pans that are not non-stick are better for producing pan gravy, because the fond (the caramelized drippings that stick to the pan when meat is cooked) sticks to them, and can be turned into pan gravy by deglazing them—dissolving them in liquid.
|This section requires expansion. (December 2009)|
- Cooking spray
- Electroless nickel plating
- Lunac (alloy and trans-ceramic coatings)
- Swiss Diamond International
- Silverstone (plastic)
- Teflon (nickname)
- Thread seal tape
- Ancient Greeks Used Portable Grills at Their Picnics, LiveScience
- How to Cook Like a Mycenaean, Archaeology Magazine
- Anne Cooper Funderburg. "Making Teflon Stick". Invention and Technology Magazine. Summer 2000 16 (1). Retrieved 2015-02-21.
- Pennie Stoyles and Peter Pentland (2007). "Non-stick pan". A to Z of Inventions and Inventors: M to P. Black Rabbit Books. p. 17. ISBN 9781583407899.
- Nicholas J. Wall, US 5069937 "Thermal spraying of stainless steel", 1988
- Laurence W. McKeen, Fluorinated coatings and finishes handbook, 2006, p. 117
- Excalibur brochure, PDF
- "Safety of Teflon Non-Stick Coatings for Cookware". DuPont. Archived from the original on 2008-01-17. Retrieved 2009-05-06.
- Jane Houlihan et al. "EWG finds heated Teflon pans can turn toxic faster than DuPont claims". EWG. Retrieved 2009-05-06.
- American Cancer Society, Teflon and Perfluorooctanoic Acid (PFOA)
- Tugend, Alina (October 14, 2006). "Teflon Is Great for Politicians, but Is It Safe for Regular People?". New York Times. Retrieved 15 September 2013.
- Juliet Eilperin: Harmful Teflon Chemical To Be Eliminated by 2015. The Washington Post, 2006-01-26
- Tony Polombo (2006). "Pots and Pans". Cooking. iUniverse. p. 20. ISBN 9780595378661.