A method for making a film having improved wettability properties for use with a heat exchanger of a condensing furnace or an air conditioner. The film can be made of any thermoplastic film which bonds to metal. Polar particulates are mechanically are adhered to and embedded in the upper surface of the heated film. The particulate can be surface treated to either enhance adhesion of the particulate to the film or to enhance wettability. In another embodiment, the film is coated with an adhesive substance or a mixture of reactants, the particulate pressed into and adhered to the coating.