Review on Nikwax Spray-On Waterproofing for Wax Cotton Fabric, 10 oz. / 300ml by James Cabot

Works great! Think Elmer's white clothes glue. Yes, I know it sounds weird, but instead of gluing things together, it forms a waterproof barrier on clothing. Smells like Elmer's, like a wax coating. Must be reapplied after every wash. Be sure to wash clothing before application, apply product and rub into fabric, turn inside out and tumble dry only 80% dry. Then let it air dry!