every small volume unit of emulsion has to pass close to the stirrer
tip to allow formation of the smallest droplets obtainable.
This brings us to what may be considered the most important point.
Formation of small drops (bubbles) involves a number of different
processes, roughly illustrated in Figure 11.10. Drops are deformed
and may or may not be broken up. Moreover, drops frequently
encounter each other and this may or may not lead to their
(re)coalescence. In the meantime, surfactant adsorbs, which affects
the result of the various processes. Each of these processes has its
own time scale, depending on a number of variables. All of the
processes occur numerous (say, 100) times during stirring, beating,
homogenizing, etc., starting with large drops that gradually give rise
to smaller ones. Finally, a steady state may be reached, in which
disruption and recoalescence balance each other. In practice, such a
state is generally not quite reached.FIGURE11.10 Various processes occurring during making of small drops (or
bubbles). The drops are depicted by thin lines and the surfactant by heavy lines and
dots. Highly schematic and not to scale.