Method for the preparation of biliquid foam compositions

A method for the preparation of a biliquid foam composition without formation of a gas foam, which method comprises the steps of:

• i) introducing into a mixing vessel equipped with a stirrer having a single or a multiplicity of stirrer blades, a continuous polar phase which optionally contains a surfactant for the preparation of the biliquid foam, the stirrer operating in a manner such that at least one part of the stirrer mechanism breaks the interface between the continuous polar phase and the air;
• ii) stirring the continuous polar phase;
• iii) adding a non-polar phase which optionally contains a surfactant for the preparation of the biliquid foam at least initially at a controlled rate to the continuous polar phase whilst continuing stirring, the rate of addition of the non-polar phase being controlled so that the droplets of the non-polar phase which lie on the surface of the continuous polar phase are broken up into smaller droplets by the action of the stirrer blade breaking the interface between the continuous polar phase and the non-polar phase;
• a slurfactant being included in at least one of the polar or non-polar phases;
• and
• iv) thereby forming a plurality of biliquid foam particles comprising non-polar phase droplets encapsulated in a film of the continuous polar phase, which particles act as nucleating sites providing additional surfaces for the preparation of the biliquid foam.