The distribution of filler particles in printing papers increases in importance with increasing filler content. In this paper it is shown that conclusions about the chalk distribution can be made from formation measurements on sheets before and after removing the chalk respectively. Chalk can be chemically removed using an HC1-Propanol solution.
Measurements of filler distribution have been made on fine paper containing 35-70% chalk. The sheets were formed in a twin wire, roll former laboratory machine at 500 m/min. A three component dry strength,/retention aid system was used, including starch, one anionic polymer component, and one cationic polymer component. Both when using a strategy for maximum retention and for optimum formation it was found that the local filler grammage was proportional to the local fiber grammage.
Measurements of formation on base paper and roll coated paper respectively revealed that there is a strong negative correlation between local filler grammage and local fiber grammage, which results in very even formation of the coated sheet.