ABSTRACT
Far less attention has been paid to antifoam action in nonaqueous systems than in aqueous systems. Presumably this reflects foam problems of a less severe nature. Formation of an unstable oil bridge in a foam film is a critical aspect of antifoam action, which requires that an oil drop can emerge into the air-water surface. Presence of metastable pseudo emulsion film could represent a significant barrier to the emergence of that oil drop into air-water surface which could even potentially eliminate any antifoam action by the oil. A requirement for antifoam action is that the oil must emerge into the air-water surface. In the case of aqueous foaming liquids, the antifoams usually consist of mixtures of hydrophobic oils and particles. Rupture as a result of van der Waals forces across the drop will eventually occur at that point leading to film rupture. This is of course the bridging stretching mechanism of Denkov and coworkers for which there is observational evidence.
