The electrokinetic euphoria which gripped the paper industry a few years ago gradually subsided when it became clear that the zeta potential is not the panacea many people, particularly instrument manufacturers, had hoped it to be. This may have the salutary effect that electrokinetic phenomena, which undoubtedly occur in papermaking, are seen to be part of a complex of physico-chemical processes to which they make different contributions under different circumstances. It may well become the order of the day in the immediate future to study case histories in the hope that one day some more general rules may emerge. This is one of the reasons why the second half of this session is given to a number of short contributions, unusual for these symposia but a step we decided to take because it seemed the right thing to do.
The purpose of my own short contribution to this first and more academic half of the session is not to provide one of those case studies but to report on a simple observation in the laboratory which, if our interpretation is correct, would be very much at variance with the established concept of the electric double layer and the various models built around it.