  Whereas our understanding of the role and mechanism of wall slip has improved
substantially over the last decade or two, it is still common to see papers on
disperse systems appear wherein scant details of the measurement methods are
given and wherein no mention of the possibility (probability?) of slip is made.
It is argued that there is a need to raise awareness. It takes experience,
judgement and skill to make meaningful measurements on disperse systems and it
is suspected that the nature of the experimental challenge is under-estimated
grossly by too many workers even now.
