Durable water repellent, or DWR, is a coating added to fabrics at the factory to make them water-resistant (hydrophobic). Most factory-applied treatments are fluoropolymer based; these applications are quite thin and not always effective. Durable water repellents are commonly used in conjunction with waterproof breathable fabrics such as Gore-Tex to prevent the outer layer of fabric from becoming saturated with water. This saturation, called 'wetting out,' can reduce the garment's breathability (moisture transport through the breathable membrane) and let water through. As the DWR wears off over time, re-treatment is recommended when necessary. Many spray-on and wash-in products for treatment of non-waterproof garments and re-treatment of proofed garments losing their water-repellency are available.
Methods for factory application of DWR treatments involve applying a solution of a chemical onto the surface of the fabric by spraying or dipping, or chemical vapor deposition (CVD). The advantages of CVD include reducing the use of environmentally harmful solvents; requiring less DWR; and an extremely thin waterproof layer that has less effect on the natural look and feel of the fabric.
Some researchers have suggested that the use of PFAS in water-repellent clothing is over-engineering, and comparable performance can be achieved using specific silicon- and hydrocarbon-based finishes.[1][2]
Re-treating garments
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Certain types of fabrics need to be re-treated to maintain water-repellency, as fluoropolymers decompose over time when exposed to water and chemicals.[3] Washing the garment with harsh detergents usually accelerates DWR loss; in addition, soaps often leave a residue which attracts water and dirt.[4] On the other hand, rain water or salt water affects DWRs less significantly.[citation needed] Affected garments can be treated with a 'spray-on' or 'wash-in' treatment to improve water-repellency. In some cases heat treatment can reactivate the factory applied repellent finish and aid in the repelling of water, and other liquids such as oils. On the other hand, some DWR products do not require heat treatment to be activated, and sometimes DWR treatments can be revitalized simply by washing the fabric with a suitable cleaner.
Cravenette
editCravenette was an old process to make cloths water-repellent. It was a performance finish that repelled water.[5][6][7][8][9][10] Various U.S.-based suppliers, such as A. Murphy, W.G. Hitchcock, and H. Herrmann, were offering Cravenette-treated cloths in the early 20th century.[11]
See also
editReferences
edit- ^ Philippa J. Hill, Mark Taylor, Parikshit Goswami, Richard S. Blackburn. "Substitution of PFAS chemistry in outdoor apparel and the impact on repellency performance." Chemosphere, 2017, 181, 500-507. doi:10.1016/j.chemosphere.2017.04.122
- ^ Steffen Schellenberger, Philippa J. Hill, Oscar Levenstam, Phillip Gillgard, Ian T. Cousins, Mark Taylor, Richard S. Blackburn. "Highly fluorinated chemicals in functional textiles can be replaced by re-evaluating liquid repellency and end-user requirements." Journal of Cleaner Production, 2019, 217, 134-143. doi:10.1016/j.jclepro.2019.01.160
- ^ Lower, Stephen (2 July 2014). "10.2: The Liquid State". UC Davis ChemWiki. Retrieved 13 September 2015.
- ^ Fowler, Will. "How to Re-Treat Garments". Sani-Tred. Retrieved 13 September 2015.
- ^ "Definition of CRAVENETTE". www.merriam-webster.com. Retrieved 2021-07-24.
- ^ Company, Sears, Roebuck and (1922). Catalog. Sears, Roebuck. p. 67.
{{cite book}}:|last=has generic name (help)CS1 maint: multiple names: authors list (link) - ^ The Saturday Evening Post. 1952. pp. 64, 87.
- ^ Winge, Jane (1981). Fabric Finishes. Cooperative Extension Service, North Dakota State University. p. 7.
- ^ US1197304A, Pearson, Herbert P., "Process for proofing hats of straw and the like and said product", issued 1916-09-05
- ^ US2448247A, Bellwood, Carl R., "Treatment of textiles with acyloxysubstituted aromatic acid salts", issued 1948-08-31
- ^ Treasury, United States Department of the (1905). Treasury Decisions Under the Customs, Internal Revenue, and Other Laws: Including the Decisions of the Board of General Appraisers and the Court of Customs Appeals. U.S. Government Printing Office. p. 8.