the present invention is a method of coating a substrate . first , a layer of liquid polymeric coating having a pigment and a solvent is applied to the substrate . an ultrasonic acoustic source is then provided and operated at a frequency of from about above 40 khz to provide an acoustic pressure field and an it acoustic pressure of above 190 db and directing the main lobe of the acoustic pressure field toward the layer of liquid polymeric coating . this acoustic pressure field reduces the gradient in and smoothes any uneven surface features in the liquid polymeric coating .