In the field of coating systems, Fischer (2003) reported that permeability of the nanocomposites coatings for water vapour markedly decreased with respect to the non-modified coating; a decrease of the water vapour permeability by a factor of 15 has been measured. This points to the presence of a strong bonding of the methylene blue to the clay platelets. Clay particles are homogeneously dispersed in the coating matrix, thus resulting in a fully transparent coating.