A note on the initial condition for the formation of foams

It is shown that the initial condition which is input into the model describing bubble growth in liquids needs to be re-examined for the case of rapid foam formation. The initial condition that is assumed in foam formation is the critical nucleus; it is from here that the expansion occurs. For a rapid foam formation the initial condition needs to be changed, the size adopted is that of a bubble which allows the onset of instability. This instability occurs when the pressure difference between the inside of the bubble and the outside is small and approaching a difference of the order of 1 to 2 atmospheres, this corresponds to bubble sizes of 10−4 m. This is the value that should be used as the initial condition in the differential equations expressing the growth of bubbles in the formation of a liquid foam.