Dip coated films, widely used in the coating industry, are usually measured by capacitive methods with micrometric precision. In this work, interferometric determination of thickness evolution in real time, for the first time to our best knowledge, is applied to volatile non-Newtonian liquids with several viscosities and distinct dip withdrawing speeds. Thickness evolution during the process depends on time as predicted by a power law model. Comparison with measured results (uncertainty of +/- 0.007 mu m) showed very good agreement after initial steps of the process. (C) 2009 American Institute of Chemical Engineers AIChE J, 55: 3052-3055, 2009