The streaming current detector (SCD) is an analytic device capable of measuring the streaming current created in a closed-end cylinder due to particles attached to cylinder and piston walls. Particle exchange with fresh sample in the flow-through chamber and electrical isolation of the cell provide the capability for continuous characterization of particle charge in a variety of industrial processes. Based on reports from the major marketers of SCDs, over 1,000 of these units are now in use, primarily in water treatment application for monitoring or automatic feedback control of coagulant dosage. The device is now being marketed worldwide and is also being utilized to a greater extent in other applications such as paper manufacture and slurry dewatering. In this paper, it is shown that the SCD's ability to characterize the charge on subcolloidal material can be used advantageously.