Abstract Vibrational finishing processes are finding increased application in the finishing of high end components. Despite the growing popularity of vibrational finishing, and due to limited suitable process instrumentation, understanding of underlying physical processes remains largely anecdotal and empirical, and system-independent process control remains unrealized. In this paper, particle image velocimetry (PIV) is proposed as a versatile, non-intrusive, readily available diagnostic for both studying fundamental features associated with vibrational finishing, as well as for developing system-independent control strategies. With regard to fundamental processes, PIV is used to measure surface media velocity fields and find that in our experimental system, the media flow field consists of: (i) a weak, random component having repeatable statistical properties which are sensitive to, and indicative of, changing process parameters and media selection, superposed on, (ii) a dominant, non-random component which is insensitive to changes in process parameters. Importantly, from a potential process control standpoint, it is shown that a filtered version of the random velocity component offers a system-independent, parameter-sensitive indicator of process conditions.