[More on Teflon]
This article came about after searching for a pair of hiking boots that have sufficient treads to hold me on steep mountain paths.
At a popular outdoor and camping store in Berkeley, I found that about 90% of the boots had a Gore-tex hang-tag on them. About a quarter of them were treated with an unspecified antimicrobial or -bacterial agent. I didn't want either because I get a rash from Gore-tex fabric and I surely didn't want a pesticide next to my body, which antimicrobials and antibacterials are classified as. I had to act fast because my breathing is affected by the great amount of noxious chemicals in sporting goods stores. A noxious chemical is one that is irritating or offensive and that may have a harmful effect on life.
In spite of the fact that many people are highly sensitive to harmful chemicals, they shouldn't feel like freaks. In fact, I am grateful that my body alerts me to these hidden dangers and think that readers of this article should feel the same way. However, salespeople can feel otherwise after our concerns are expressed. They may suggest we go to a place that specializes in "Berkeley sort of stuff," essentially meaning that the desire is fringe. I admit it I am rare in my concern about Gore-tex in comparison to 99.99% of any selection of shoppers in the US. But why would I want to agree with a group of people — no matter how large or prevalent in society — that assumes the safety of most of what industry feeds them, clothes them in and houses them in? My own frustration grows as it is rapidly becoming difficult to purchase clothes that don't contain some form of synthetic chemical as a part of the weave; or as a fabric treatment for any number of stated purposes. Nanoparticles are rapidly taking hold as well.
So, what is Gore-tex?
Essentially Gore-tex is a Teflon-treated synthetic polymer — a plastic. Teflon is a brand name for tetrafluoroethylene / polytetrafluoroethylene (PTFE). Generally, all plastics are made by the process of combining many toxic chemicals into long chain molecules called polymers using great heat and pressure. The process is never 100% perfect, meaning that there are always toxic chemicals that leach or migrate into whatever comes into contact with them — food, drink, air and you. Teflon is no different. Make no doubt about it, Teflon does leach toxic chemicals into whatever contacts it. According to a Russian study in 1978, in water that had contacted the material, fluor ions and organofluorine compounds were detected.(1) In another study, benzene was found.(2)
More technically, Gore-tex is a dispersion-polymerised PTFE that is patented by W. L. Gore and Associates. It is classed as a stretched semi-crystalline film, and is produced by extrusion under stress (faster take-up rate than extrusion rate). The extrudate is stretched below the melting temperature, often in the presence of an aromatic hydrocarbon that swells the amorphous region, creating porosity. The hydrophobic nature of the PTFE means that liquid water is repelled from the pores, whereas water vapour can pass through. It is important to realise that once the PTFE pores are filled with liquid water, the fabric can allow liquid water to pass though until it is dry again. Thus Gore-tex-containing fabrics (such as Nomex/Gore-tex, which consists of an outer aramid(3) fabric, a central Gore-tex layer, and a cotton backing) should never be used as protection from chemicals as many will pass straight through. Any water-miscible solvent (eg alcohol) can fill the pores, and then liquid water can displace it and continue to rapidly pass through until the fabric is fully dried out.(4)
Gore-tex is a proprietary teflonized Teflon is the brand name of a polymer compound discovered by Roy J. Plunkett (1910-1994) of DuPont in 1938 and introduced as a commercial product in 1946.
Teflon is polytetrafluoroethene (PTFE).
Teflon is also used as the trade name for a polymer with similar properties, perfluoroalkoxy polymer resin (PFA)
History: W.L. Gore & Associates, Inc. was founded in 1958 by Wilbert L. "Bill" Gore and his wife, Genevieve Gore, in Newark, Delaware. Bill Gore was a DuPont research chemist working in fluropolymers, and based on a suggestion by his son, Robert W. "Bob" Gore, he developed and patented a process for insulating wires with Teflon (DuPont's trade name for PTFE). A decade later, Bob invented Gore-Tex, an expanded form of PTFE, and the company today makes a wide range of products in the medical, industrial, electrical and fabrics fields all based on his core PTFE membrane technology invention.
Gore-tex patent: U.S. Pat. 3,962,153 (8 June 1976) R.W.Gore (to W.L.Gore and Associates). This is a continuation-in-part of application Ser. No. 39,753, filed May 21, 1970, now abandoned. source: U.S. Patent Office 4jun2005
References
F F | | R - C - C - R | | F FTeflon is also used as the trade name for a polymer with similar properties, perfluoroalkoxy polymer resin (PFA):
F F F F | | | | R - C - C - C - C - R | | | | F F F O | F - C - F | FTeflon has the lowest coefficient of friction of any solid material known to man. It is used as a non-stick coating for pans and other cookware. Teflon is very unreactive, and so is often used in containers and pipework for reactive chemicals. Its melting point varies between 260 °C (FEP) and 327 °C (PTFE), depending on which specific teflon resin is being discussed.
Teflon is sometimes said to be a spin-off from the US space program with more down-to-earth applications; this is an urban legend, as teflon cooking pans were commonplace before Yuri Gagarin's flight in 1961. PTFE was discovered serendipitously by Roy Plunkett of DuPont in 1939, while attempting to make a new CFC refrigerant. DuPont patented it in 1941, and registered the Teflon trademark in 1944.
Its first significant use was in the Manhattan Project, as a material to contain highly-reactive uranium hexafluoride, when it was known as K416.
It was first sold commercially in 1946 and by 1950, DuPont was producing over a million pounds (weight) per year in Virginia.
Teflon has been supplemented with another DuPont product, Silverstone, a three-coat fluoropolymer system that produces a more durable finish than Teflon. Silverstone was released in 1976.
Amongst many other industrial applications, Teflon is used to coat certain types of hardened, armour-piercing bullets, so as to reduce the amount of wear on the firearm's rifling. These are often mistakenly referred to as "cop-killer" bullets on account of Teflon's supposed ability to ease a bullet's passage through bullet-proof armour. Any armour-piercing effect is, however, purely a function of the bullet's velocity and rigidity rather than a property of Teflon.
Teflon exposure has been implicated in cancer, though DuPont denies any association. Non-stick coatings on household frying pans have also been shown to release toxic gases upon overheating. These gases are lethal to avians, and can cause flu-like symptoms in humans.
Teflon has excellent electrical properties especially at radio frequencies, making it eminently suitable for use as an insulator in cables and connector assemblies. Combined with its high melting temperature this makes it the material of choice as a high performance substitute for the weaker and more meltable polythene that is commonly used in low-cost applications. (source: Wikipedia 4jun2005)
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