How to do the sedimentation test of suspension and what is limit for suspension
Sedimentation rate of a suspension can be assessed by filling suspension (after proper homogenization) in 100 mL or 250 mL capacity measuring cylinder up to mark and closing the cylinder tightly with a Cork. Keep this cylinder undisturbed on a steady surface, like work bench in laboratoryour at room temperature. Observe the suspension every day for any Sedimentation at the bottom and also for any supernetant clear liquid on the top surface. Measure the volume of both on daily basis and calculate rate.
There is no specific limit for sediment, however, after briskly shaking of the cylinder the suspension should become homogeneous. Sediment should not become a hard cake which is difficult to get dispersed there by making the suspension heterogeneous. This largely depends upon type of suspending agent used and the charge on the particles (Zeta potential).