The importance of wet end chemistry is increasing, due to the trends of high speed paper making. The stability of wet end process can be achieved when agglomeration and adsorption, which are the most important phenomena, are controlled well. Therefore, all measurable parameters that explain the condition of the wet end system should be maintained at the appropriate levels. Most of these parameters used to be measured by the off-line systems, however, recently several on-line measurement systems have been developed and they make it possible to monitor the change of the wet end. In this paper, we present details of the recent online measurement systems, which have strong relation to the wet end chemistry, such as retention meter, cationic demand analyzer, and zeta potential analyzer with fundamentals and the examples of the measurements. Additionally, MOAS, entrained air analyzer, and slime monitor will be simply introduced.
