A method for the preparation of a biliquid foam which does not rely upon the initial formation of a gas foam, in which a stirrer having a single or a multiplicity of blades is used, the stirrer being operated in a manner such that at least one part of the stirrer mechanism breaks the interface between the continuous polar phase used to form the biliquid foam and the air, the non-polar phase being added dropwise at least initially whilst stirring the continuous polar phase and the rate of addition of the non-polar phase being controlled so that a biliquid foam composition is formed.