A new look at how fines influence the strength of filled papers

The ability of kraft pulp fines to strengthen PCC filled paper was quantified by measuring the force to delaminate two-ply laminated handsheets made with a layer of fines and fillers at the ply/ply interface. Fines were particularly effective at compensating for the strength loss induced by the presence of fillers. Secondary fines, produced by refining softwood bleached kraft pulp were significantly more effective than the more chunky primary fines separated from the original market pulp.