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Durable Water Repellent

DWR (Durable Water Repellent) is a coating added to fabrics to make them water-resistant. Durable water repellents are often used in conjunction with waterproof breathable fabrics such as Gore-Tex to prevent the outer layer of a laminated waterproof breathable from becoming saturated with water. Maintaining the DWR is critical to maintaining the breathable nature of waterproof breathable outerwear.

Brands

Garments made of waterproof breathable fabrics are treated with DWR at the factory, and don't need treatment before using. The finish wears off eventually, but the repellency can be re-applied using sprays or wash-in products. Common brands of DWR finishes include:

• Nikwax (patented wax-elastomer base)
• ReviveX (fluoropolymer base)
• Scotchgard (fluoropolymer base)
• Tectron (fluoropolymer base)
• Kiwi Camp Dry (silicone base)
• Granger's (fluoropolymer base)

Care

Despite the name, durable water repellent finishes tend to wear off and may need to be re-applied from time to time. The application method will probably make a big difference in the DWR you choose to use. Most fabric treatments are applied either by adding to a regular wash cycle in a washing machine, or by spraying. Keeping the fabric clean is also an essential part of maintaining the integrity of the outerfabric.

Fluoropolymer-type repellents tend to lose their properties when washing. Such garments need tumble drying in medium heat or ironing to restore the repellency.

WARNING: While fluoropolymers offer a high level of water repellency, as well as a high degree of oil and stain repellency, everyday users should be aware that fluoropolymer compounds degrade into PFOA's. PFOA's have been suspected by the EPA (United States Environmental Protection Agency) to be carcinogenic to humans.

References

• Ellis, D.A.; Mabury, S.A.; Martin, J.W.; Muir, D.C.G. "Thermolysis of fluoropolymers as a potential source of halogenated organic acids in the environment." Nature 2001, 412 (6844), pp. 321-324.

• Draft Risk Assessment of the Potential Human Health Effects Associated With Exposure to Perfluorooctanoic Acid and Its Salts (PFOA), U.S. EPA, 2005, p. 8.