With a view to evaluate the mass distribution in a paper sheet on real-time basis, the images of flocs were taken using two light projecting systems : TV monitor and strobe light. These images were fed into an image processing unit and the mass density was expressed as the level of grey scales. The mass distribution obtained by the image processing method showed a good correlation with that obtained by the conventional soft x-ray method within the limit of the present experimental conditions.
These findings suggest the possibility of obtaining the mass distribution more speedily and more easily by analyzing the transmitted light through the sheet.
The sequence of addition of additives to the stock highly affects the frequency of formation of flocs.
It is also suggested that the dual polymer system in this investigation helps to increase homogeneous mass distribution in a sheet as well as the increase in retention of fillers. The z-direction distribution of fillers in a sheet tends to be homogeneous in a dual system, however, the mechanism remains to be solved.