The present invention relates to a method for altering the surface tension in interfaces formed between a liquid and a gaseous phase in which the vapour of the liquid in question dissolves, characterised by controlling the vapour concentration in the gaseous phase. If the liquid is an aqueous solution and the gaseous phase is air, the method for altering the surface tension consists of altering the relative humidity of the air, increasing same, for example, by using some sort of humidifier in order to reduce the surface tension, or reducing same, for example, by using any sort of desiccator in order to increase the surface tension.