US Patent No. 10,548,820 B2; Cindi Klar-Barna and Corey Barna of New York, NY patented a method for filling a nail polish bottle with a nail polish composition. It entails placing a nail polish bottle to be filled with nail polish at an angle relative to a horizontal plane; filling a first portion at an angle with a first nail polish layer comprising a first coloring material, which exhibits a first characteristic color, dissolved therein; waiting until a first film layer forms over said first nail polish layer; and filling a second portion of the bottle at an angle with a second nail polish layer comprising a second coloring material, which exhibits a second characteristic color, dissolved therein. The first and second nail polish layers are separated by a film layer.