Abstract: A process of treating sheet materials with an aqueous treating composition is disclosed in which surfactants are incorporated in the composition to permit it to be foamed with gas to provide a foam which is stable in the form of a thin layer long enough to be handled, but which will collapse completely when heated. This is preferably done by employing a mixture of water soluble surfactant to stabilize the foam and water insoluble defoamer to break the foam when heat is applied. This foam is applied to a surface of the sheet material to provide stable foam thereon, and heat is employed to simultaneously cause the foam to collapse and dry the composition.