A coating comprises a resin solution including a solution of neoprene latex and liquid asphalt emulsion and an accelerator solution including an aqueous solution of zinc sulfate powder and water. A spray system for applying the coating includes a spray gun having first and second nozzles, a first pump fluidly connected between the first nozzle and a resin solution reservoir for delivering the resin solution to the first nozzle at a first fluid pressure, and a second pump fluidly connected between the second nozzle and an accelerator solution reservoir for delivering the accelerator solution to the second nozzle at a second fluid pressure different from the first pressure. The accelerator solution may be aerated by a source of compressed air prior to discharge from the second nozzle.