Viscometer vs. Rheometer: Which Is The Better Choice?

This is the type of query that comes in from customers to instrument manufacturers on a frequent basis. It may go somewhat like the following set of statements and questions.

We produce certain thickeners and thinning agents used by the pharmaceutical industry in their formulation of creams and ointments. We want to purchase a new viscometer (although our local dealer suggests a rheometer). In our understanding, the rheometer can perform the function of the viscometer (and more). A possible downside may be the inability to match the standard industry protocol for a specific QC test method. Is this a correct statement in general terms? If the rheometer is the better instrument, why can’t it match the standard industry test? Is there any other difference or disadvantage to consider? Finally, please advise which model of rheometer with accessories is most suitable for our application.

Pharmaceutical manufacturers generally find that rheometers offer several major benefits, in particular a broader range of test capabilities compared to the standard bench top viscometer. If that test capability can be combined with rugged construction of instrument for use in QC, which lengthens the time interval between service appointments, then the choice of a rheometer over a viscometer may be more practical to consider. If cost is affordable, then the same instrument may prove effective in both applications.