Fibre Alignment
Drainage dynamics on the forming table dictate how fibre orientation establishes across a running web. Liquid suspension forces push cellulose strands into specific trajectories as the stock contacts the moving mesh. Machine direction tension pulls suspended pulp into parallel arrangements during early dewatering phases.
Cross direction profiles shift when slice lip openings distribute pulp unevenly across the width of the sheet. Resulting directional ratios control stiffness and tear propagation values in finished corrugated containers and folding boxboards.
Surface Uniformity
Microscopic voids form along the top layer when drainage pressures fluctuate past established thresholds during consolidation. Drainage elements pull water downward through the forming fabric while suction boxes remove residual moisture before the press section. Uneven suction pulls fibres deeper into the mesh openings and creates localized pinholes across the substrate.
Print quality suffers on rougher zones because ink transfer drops when local caliper variations exceed standard printing tolerances.
Retention Control
Fine particle losses during initial dewatering steps alter filler distribution through the thickness of the sheet. Dual polymer systems stabilize mineral additives and short cellulose fractions within the wet web before the final pressing stages. Polymer chains bridge suspended solids together and prevent them from draining through the plastic mesh into white water loops.
Mechanical retention levels determine opacity and brightness metrics for high speed offset printing papers without increasing basis weight targets.
