Gore-Tex & Waterproofs

Clothing Waterproofing

Clothing waterproofing includes treatments made to clothing or products during or after the production process, which provides some protection against exposure to water. The extent to which the item is protected can vary by extended exposure, water depth, water composition, salts, chemicals etc., and the quality or method of treatment. Products which are waterproofed can be made so by applying a waterproof spray, such as NIKWAX.

Waterproof Fabrics

Waterproof fabrics are usually natural or synthetic fabrics that are laminated to or coated in some sort of permanently waterproofing material, such as rubber, polyvinyl chloride (PVC), polyurethane (PU), silicone elastomer, and wax. Examples include the rubberised fabric used in Mackintosh jackets and inflatable boats.

Waterproof breathable fabrics

Waterproof breathable fabrics (aka waterproofs, waterproof breathable and waterproof-breathable) are defined as fabrics that will withstand over 1000 millimetres of water (9.8 kPa) pressure without leaking (hydrostatic head), whilst allowing water vapour to pass through. Their most common use is in outdoor sports clothing and single wall tents, because of their ability to allow sweat to evaporate while remaining impervious to rain.
Rain room tests show that certain fabrics with less than 1,000 millimetres hydrostatic head can keep you dry. Such garments tested in the Leeds University Rain Room show no signs of leakage after 4 hours of heavy simulated rain, 5 times heavy British rain. However, some garments made from fabrics that exceed 20,000mm have leaked due to the design of zips, hoods etc. Pressure may not be a good measure for rain wear, as the force of the rain drop on the fabric depends on how much the fabric moves. However, pressure is a good measure for sitting on wet ground or similar situations.
Fabric construction which directs water away from the body can be used to keep the wearer dry, rather than membranes, coatings or laminates. This means that perspiration can be moved away from the body more effectively as both liquid water and water vapour can be directed. These are Directional^TM or FurTech^TM fabrics, which are also breathable in the conventional sense.
The breathability of all waterproof/breathable fabrics is very dependant on conditions. When the fabrics become chilled or humidity is high, the dew point may be reached and condensation will occur.

Some common waterproof/breathable fabrics are:

• Gore-Tex by W.L. Gore & Associates
• Sympatex
• Ventile by Ventile
• eVent® fabrics
• Nikwax Directional Textiles as used by Páramo Directional Clothing Systems
• 3-ply Entrant-EV™membrane Mountain Equipment Co-op
• Entrant by Toray Industries, Inc.
• Drilite Extreme, made by Mountain Equipment
• HyVent, made for The North Face by Toray.
• H2No, made for Patagonia, by Toray.
• Omni-Tech by Columbia
• Conduit, made by Mountain Hardwear
• Triplepoint Ceramic, made by Lowe Alpine
• Precip, made by Marmot
• Watergate, made by Outdoor Designs
• Polymer-encapsulated cotton EPIC, made by Nextec
• Wax impregnated cotton or cotton/polyester mixes (such as those used in Barbour coats and Fjällräven's G-1000 fabric)
• Hyper-Dri by Mark's Work Wearhouse

Gore-Tex

Gore-Tex (abbreviated GTX) is a registered trademark of W.L. Gore & Associates best known for its use in relation to waterproof/breathable fabrics. The first commercial consumer product using Gore-Tex was a tent called the Light Dimension that was created and sold by the Seattle firm, Early Winters, Ltd., in 1976. Gore-Tex was co-invented by Wilbert L. Gore (1912-1986) Rowena Taylor and his son, Robert W. Gore. For its invention, Robert W. Gore was inducted into the National Inventors Hall of Fame in 2006. WL Gore and Associates is known for its unique corporate structure. It has consistently been placed on the Fortune magazine top 100 companies to work for worldwide.

Gore-Tex membrane, electron microphotograph

Robert Gore was granted U.S. Patent in 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 a U.S. Patent in 1980 for a "waterproof laminate". Gore-Tex is used for outdoor clothing, gloves, hats and waterproof boots

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. Gore-Tex based fabric material is composed of a thin, porous fluoropolymer membrane with a urethane coating that is bonded to a fabric, usually nylon or polyester. The membrane has about 9 billion pores per square inch (around 1.4 billion pores per square centimetre), each of which is approximately 20,000 times smaller than a water droplet, making it impenetrable to liquid water while still allowing the smaller sized water vapour to pass through. The result is a material that is breathable, waterproof, and also windproof. The outer fabric is treated with water repellent and seams are sealed to prevent water leakage through pinholes caused during the sewing of the fabric. The urethane coating provides a protective layer and also prevents contamination (i.e. body oils) from wetting the laminate and allowing wicking of moisture through the membrane.

Schematic diagram of a composite Gore-Tex fabric for outdoor clothing

The best known application for Gore-Tex fabrics is in outdoor activity clothing.
In this context, it helps keep the wearer protected from the wind and rain, while nonetheless allowing sweat to evaporate and escape. This is in contrast to traditional plastic raincoats, for example, which lack breathability and therefore promote a build up of humidity in the air inside the coat, preventing sweat from evaporating effectively.
Gore-Tex is also used in surgery as an implant material, patch or membrane, such as in plastic surgery and heart surgery.
Gore 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.