Renewing DWR
Every fabric finish we have tested will wear out with enough use. A fabric can be waterproof on one side and wet on the other. THe DWR finishes help water bead off and help keep fabrics clean. We had the question asked “what would you use to renew the DWR finish on a cushion after a few seasons?” Of all the products we have tested, Granger’s is the product that we like the best. It works well and is available at most camping stores or Cabelas. It is odorless and easy to use and is reasonably priced. Developed in the U.K. Granger’s has a number of products for clothes, etc. - for a cushion use the tent and awning spray.
http://www.grangersusa.com/products/tent-and-gear-uv-waterproofing.html