Less is more: Unstable foams clean better than stable foams

Foamed surfactant solutions can clean surfaces! We hypothesise that the cleaning efficiency depends on liquid fraction and stability of foam. also is better smaller average bubble size is. The double syringe technique was used to generate foams with varying fractions but same, very small sizes without perfluorohexane in gas phase. performed tests which were applied glass substrates contaminated a fluorescent oil. found unstable than stable foams. Three mechanisms identified: (1) imbibition at low fractions, (2) wiping, i.e., shifting contact line between oil, foam glass, all (3) drainage high fractions. change lead different combinations these thus results.