The invention relates to a composition which, when mixed with a polymer composition, allows for the formation of a continuous and cohesive film. The film is characterized in that it provides water, grease and oil resistance, provides a water vapor barrier and can used as wax replacement treatment and a top coat for flexible packaging, but also on other substrates. This film is formed at a very fast set speed without the need of thermal energy. The composition contains i) a salt of one or more of myristic, palmitic and stearic acid; and preferably also ii) a C9-C18 fatty acid complex of a metal ion, the metal ion having an oxidation state of at least 3. The invention also provides processes and coated substrates.