It was 64% lower than that of paper coated with caseinate/chitosan “bilayer coating 1” with 9 g/m2 (Fig. 2). It seems that the greatest reduction in paper WVP is achieved by addition of a chitosan layer to the dried preformed caseinate-coated paper, due to the thickness effect. In contrast to hydrophobic synthetic polymeric materials, the WVP of films prepared from biopolymers depend on their thickness (McHugh, Avena-Bustillos, & Krochta, 1993). “Bilayer coatings 2” produced by application of chitosan solution as a second layer on dry caseinate films were thicker compared with single-layer coatings, and the 12% caseinate/chitosan “bilayer coatings 2” were the thickest (Fig. 1). Literature demonstrates that bilayer systems are more effective barrier against water vapor transfer than composite films (Rivero, Garcia, & Pinotti, 2009).