Experimental evidence suggests that frosting on emulsion paint films may be caused by the following factors: (1) soluble components in the paint film itself, e.g., wetting and dispersing agents; (2) diffusion of soluble salts to the film surface after incorrect pretreatment; (3) migration of soluble salts from the substrate to the film surface; (4) the influence of acid components in the atmosphere on the film surface following degradation of the binder and reaction with pigments and extenders; (5) a deposit of atmospheric pollutants on the film surface and the formation of crystals resulting from a reaction with atmospheric moisture; and (6) a combination of the above. Results of experiments are presented. -- AATA