Environmental concerns associated with the level of volatile organic compounds used in surface coatings have stimulated increased scientific research toward novel methods of developing environment-friendly coatings. Prototype wood finish products containing polymerized whey proteins (PWP) were formulated. The microstructural characteristics of dry films prepared from environment-friendly wood finishes containing PWP were examined using atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). The susceptibility of the coatings to microbial degradation was also examined using an accelerated mold test. AFM analysis revealed that increased addition of PWP resulted in films with increased surface roughness, decreased number of voids, and increased void size due to excessive aggregation among polymer components. CLSM analysis showed that the PWP distribution in the films is enhanced by homogenization of the coating mixes. There was no significant increase (P > 0.05) in mold growth between panels coated with finish containing PWP and those without PWP. Test panels coated with formulation containing PWP and low levels of biocide (0.3%) resulted in a significant decrease in mold growth in comparison to commercially available water-based polyurethane coatings (P < 0.05). (c) 2006 Wiley Periodicals, Inc.