If you want to reapply or add another coat over the existing material, stay within the recoat window. The high pressure and Qwik Spray formulas have a recoat window of 20 minutes while the brushables have a recoat window of 4 hours. If you want to apply another coat after the window passes, you will have to sand the material to ensure adhesion between subsequent coats. A primer can also be used to generate adhesion between layers.