Lifetime of vertical giant soap films: role of the relative humidity and film dimensions.

We consider the lifetime of rectangular vertical soap films and we explore the influence of relative humidity and both dimensions on the stability of large soap films, reaching heights of up to 1.2 m. Using an automated rupture detection system, we achieve a robust statistical measurement of their lifetimes and we also measure the film thinning dynamics. We demonstrate that drainage has a negligible impact on the film stability as opposed to evaporation. To do so, we compare the measured lifetimes with predictions from the Boulogne & Dollet model, originally designed to describe the convective evaporation of hydrogels. Interestingly, we show that this model can predict a maximum film lifetime for all sizes.