When wicks are used to form weeps above flashing in masonry walls, they are usually made of cotton. Over time, however, the cotton will rot away and no longer wick water. Is there a better synthetic material that can be substituted?
I would not recommend using a synthetic material for a wick. Cotton is the best material I know for wicking water. Synthetics such as nylon or polypropylene will not wick water effectively. When the cotton wicks rot away, the void created will provide a path for water to exit the wall.