Measurement of the temperature decrease in evaporating soap films

TL;DR

This study investigates how evaporation causes soap films to cool significantly after formation, affecting their stability and dynamics, with experimental measurements and a supporting model.

Contribution

It provides the first quantitative analysis of soap film cooling due to evaporation, highlighting its importance in understanding film stability.

Findings

Soap films can cool up to 8°C after creation.

A model accurately predicts the temperature drop.

Cooling effects are significant for soap film dynamics.

Abstract

Recent advances have demonstrated that evaporation can play a significant role on soap film stability, which is a key concern in many industrial areas but also for children playing with bubbles. Thus, evaporation leads to a film thinning but also to a film cooling, which has been overlooked for soapy objects. Here, we study the temperature variation of an evaporating soap film for different values of relative humidity and glycerol concentrations. We evidence that the temperature of soap films can decrease after their creation up to 8$~^\text{o}$C. We propose a model describing the temperature drop of soap films after their formation that is in quantitative agreement with our experiments. We emphasize that this cooling effect is significant and must be carefully considered in future studies on the dynamics of soap films.