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GORE-TEX is a waterproof/breathable fabric, and a registered trademark of W.L. Gore & Associates. It was co-invented by Wilbert L. Gore (1912-1986), Rowena Taylor, and Gore's son, Robert W. Gore for use in space. Robert Gore was granted U.S. Patent 3,953,566 on April 27, 1976, for a porous form of polytetrafluoroethylene with a micro-structure characterized by nodes interconnected by fibrils. Robert Gore, Rowena Taylor, and Samuel Allen were granted U.S. Patent 4,194,041 on 18 March 1980 for a "waterproof laminate." For its invention, Robert W. Gore was inducted into the National Inventors Hall of Fame in 2006.
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Manufacture
Gore-Tex is manufactured using polytetrafluoroethylene (PTFE). PTFE is made using the controversial chemical perfluorooctanoic acid (PFOA, also known as C8).1 For the general population, blood serum levels of PFOA have been linked to lower birth weight in babies.23 In response to media coverage from these two studies, the American Council on Science and Health labeled the idea that "PFOA Causes Low Birth Weight Babies" as #4 on their Top Ten Unfounded Health Scares of 2007, arguing that "PFOA affecting birth weight by four ounces does not imply any real harm to the babies - they were all of normal weight."4 In January 2006, the U.S. Environmental Protection Agency (EPA) initiated the PFOA Stewardship Program, in which major companies producing PTFE and other fluoropolymers committed voluntarily to reduce facility emissions and product content of PFOA and related chemicals on a global basis by 95 percent no later than 2010, and to work toward eliminating emissions and product content of these chemicals by 2015.5 EPA's position regarding consumer products made with PTFE or other fluoropolymers is that "at the present time, EPA does not believe there is any reason for consumers to stop using any products because of concerns about PFOA."6
Design
Gore-Tex materials are typically based on thermo-mechanically expanded polytetrafluoroethylene (PTFE) and other fluoropolymer products. They are used in a wide variety of applications such as high performance fabrics, medical implants, filter media, insulation for wires and cables, gaskets, and sealants. But Gore-Tex is best known for its use in protective rain wear.
The simplest sort of rain wear is a two layer sandwich. The outer layer is typically nylon or polyester and provides strength. The inner one is polyurethane, aka PU, and provides water resistance, at the cost of breathability.
Early Gore-Tex fabric replaced the inner layer of PU with a thin, porous fluoropolymer membrane (Teflon) with a polyurethane coating that is bonded to a fabric, usually nylon or polyester. This membrane had about 9 billion pores per square inch (around 1.4 billion pores per square centimeter), each of which is approximately 1/20,000 the size of a water droplet, making it impenetrable to liquid water while still allowing the smaller sized water vapour to pass through.
However it was found that when used in clothing the exposed Teflon membrane layer was easily damaged, as well as being compromised by exposure to the wearer's own sweat. As a result a third layer was added - a coating of PU on the inside of the fabric to protect the membrane.7 This final design has been criticized as offering greatly reduced performance and more marketing benefits than performance ones.8
More recent fabrics such as eVent and Epic avoid the need for this inner PU coating9 and have been shown to have have higher breathability as a result, while still being rainproof.10
Performance and comparison with other breathable fabrics
The suitability of Gore-Tex for high performance clothes for outdoor aerobic activities such as hiking, cross country skiing, and cycling, etc, has been particularly questioned:
The problem with Gore-Tex in warm weather is precisely that the quantity of sweat vapor it can pass is extremely limited. Without true breathability, the heat and then the humidity inside the suit rises quickly to the saturation point, turning sweat vapor into wet, liquid sweat at the Gore-Tex barrier...
In colder weather.. an athlete will be wearing some form of underclothing which will ordinarily absorb some of his sweat, both as liquid and as vapor. This is undesirable because it means the underclothing traps the very heat load the body is trying to rid itself of. Worse yet, after the exercise is over, evaporation of damp underclothing may cause over-cooling of a fatigued athlete, already cold from cessation of activity...
...As clothing, Gore-Tex does its thing best in hot, dry air—precisely when it would be least desirable because of the enormous heat load it would cause. In cool, wet weather it works best when the user is not exercising vigorously. The ubiquitous tan raincoat seen on every commuter who ever wore a white collar would seem to be a perfect, huge market. So would the market for golf jackets, car coats and wind breakers when these products are used for casual activities such as walking and spectating.
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Care of Goretex fabric
- As dirt - and even human sweat - will block the pores that allow Goretex to breathe, clothing that uses it should be kept clean for performance as well as hygiene and appearance reasons.
- Both wear and cleaning will reduce the waterproofness of Goretex clothes by wearing away the Durable Water Repellent (DWR) treatment on the surface of the fabric. However this can be restored by tumble drying your garment.
- A guide to maintaining Goretex fabrics is available.11
Other uses
Gore-Tex requires that all garments made from their material have taping over the seams, to eliminate leaks. Gore's sister product, Windstopper, is similar to Gore-Tex in being windproof and breathable, but (1) has ability to stretch and (2) is not waterproof. Gore-Tex is playing an increasing role in the conservation of illuminated manuscripts.12
A specially-coated form of Gore-Tex material is the key component of a new fuel cell design of hybrid cars which could make the vehicles more reliable and cheaper to build. 13
See also
References
- ^ Renner, Rebecca: "Concerns over common perfluorinated surfactant" Environmental Science & Technology Online. (May 1, 2003). Accessed October 25, 2008.
- ^ Crystal Phend, Reviewed by Zalman S. Agus "Nonstick Chemical Linked to Lower Birth Weight" MedPage Today (August 27, 2007). Accessed November 1, 2008.
- ^ Betts K (Nov 2007). "PFOS and PFOA in humans: new study links prenatal exposure to lower birth weight". Environ Health Perspect. 115 (11): A550. PMID 18007977.
- ^ American Council on Science and Health: "Top Ten Unfounded Health Scares of 2007 #4: PFOA Causes Low Birth Weight Babies" (December 19, 2007). Accessed October 18, 2008.
- ^ 2010/2015 PFOA Product Stewardship Program http://www.epa.gov/oppt/pfoa/pubs/pfoastewardship.htm
- ^ EPA PFOA website accessed November 24, 2008. http://www.epa.gov/oppt/pfoa/
- ^ Rainwear
- ^ Shopping for waterproof raincoats. - By Seth Stevenson - Slate Magazine
- ^ FabricLink | Search by Trademark
- ^ http://www.prolitegear.com/site/xdpy/kb/00029/index.html
- ^ How To Take Care Of Gore-Tex
- ^ Singer, Hannah. “The Conservation of Parchment Objects Using Gore-Tex Laminate.” The Paper Conservator 16, 1992: 40-45.
- ^ http://www.monash.edu.au/news/newsline/story/1310 Monash fuels the next generation of Hybrid cars
