Twenty-five years ago, wet end chemistry was viewed as a field so complex that we could not understand or control its behavior. This viewpoint was supported by the fact that a papermaking system has multiple, sometimes uncontrolled inputs and feedback loops affecting this chemistry. On top of this, most wet end chemistry reactions are irreversible, time dependent, and impacted by interfering and interacting mechanical factors. In addition, there are often simultaneous competing aggregation and dispersion chemistries, along with very limited online data.1