Polymer Barrier Coatings and Pulpability Test Standards
Polymer barrier paperboard compliance requires passing 0.15mm laboratory slot screening with under 15 percent reject mass to prevent EPR fee penalties.
Filtrate Turbidity
Liquid Purity
Solid separation relies on filtrate turbidity to gauge the clarity of water drawn from pulp washing stages or dewatering presses. Suspended fines and colloidal debris pass through filter media when retention aids fail or vacuum levels spike beyond standard thresholds. Papermakers track this clarity metric to prevent closed loop accumulation of fillers and short fibres that foul shower nozzles and disrupt wet end chemistry.
Excess solids signal damaged wire mesh or incorrect polymer dosing during sheet formation.
Drainage Resistance
Sheet permeability drops sharply when high solids loading blinds the felt and restricts water removal under pressing rolls. Machine speed adjustments compensate for slow drainage only until dryer energy demands exceed economic limits. Fine retention efficiency dictates how much filler stays bound within the cellulose network rather than cycling back through white water loops.
Operators monitor suspended particle loads continuously to detect early signs of chemical imbalance before basis weight variations appear in finished rolls.
Retention Control
Wet end chemistry balances flocculation mechanics against shear forces in the headbox to maintain optimal particle capture. Cationic starch dosages and colloidal silica additions aggregate tiny fragments so they lodge securely between long cellulose fibres. Proper optimization of these additives reduces suspended load in drainage water and stabilizes sheet formation across wide deckle widths.
High solids measurement feedback loops adjust chemical pumps automatically when incoming stock consistency shifts.