Nanomaterials have a relatively large surface area. As particles decrease in size, a greater number may be found at the surface, creating a more reactive surface than achieved with larger-size particles. Since nanoparticles provide a larger surface area and quantum effects, it is expected that replacing existing larger-size extenders with nanosize extenders could provide better coating properties. Part 1 of this article (PCI, January 2013 issue, page 44) revealed that incorporating nanoclay into polyurethane coatings significantly improved dry adhesion as well as high-pressure hot-water-spray test properties. This article discusses the same systems tested for water, humidity and corrosion resistance.