This paper introduces the principle, applications, and results of a unique retention and ash control solution. White water consistency control is first described results and experiences from machines producing a variety of paper and board grades show that the control stabilizes consistencies in the short circulation by 40 to 80% and reduces the MD variation of the final product by 10 to 40%. Moreover, it has opened new possibilities to control the wet end.
New, comprehensive control solutions based on headbox ash Cs and thick stock ash content measurements are described together with some practical results. The paper concludes with a short overview of the further development potential in wet end control.