AbstractThe ease with which water is released from cellulosic fiber material during the manufacturing of paper can affect both the production rate and the consumption of energy during the manufacturing process. Important theoretical contributions to dewatering phenomena have been based on flow through packed beds of uniformly distributed fibers. Such descriptions are able to explain why resistance to dewatering increases as a function of the hydrodynamic surface area of fibers. More recent studies have demonstrated a critical role of finely divided matter. If the fines are unattached to fibers, then they tend to move freely through the fiber mat and plug channels in the paper web during the dewatering process. Dewatering also is affected by the deformability of cellulosic fibers and by whether the fibers easily slide past each other, thereby forming a dense mat. By emphasizing the role of fine matter, colloidal forces, and conformability of cellulosic materials, one can gain a more realistic understanding of strategies that papermakers use to enhance initial drainage and vacuum-induced dewatering.