I have Herculiner in my bed. Can I coat over it with Monstaliner?
Yes. Gently wire brush the surface to remove any loose rubber particles and embedded dirt. Wash the bed thoroughly with a water base degreaser followed by trisodium phosphate in hot water. Use a stiff scrub brush with the TSP and flush the bed thoroughly with clean water and let dry completely overnight. You are now ready to install Monstaliner.