Silent Paper Grade Furnish Substitution Mechanics at Machine Gate
Furnish substitutions at the machine gate require wet end NIR tracking and ISO 1924 tensile verification to prevent runnability failures and yield losses
Cationic Starch Loading
Wet End Addition
Chemical dry-strength addition modifies wet-end papermaking chemistry to improve internal fiber bonding and fine retention. Wet-end chemical systems add cationic starch loading into the fiber slurry before headbox delivery to bind negatively charged wood fibers and mineral fillers. The process applies to aqueous paper stock suspensions containing cellulosics and inorganic pigments.
The wet-end addition boundary stops at the point of web formation on the forming wire.
Electrokinetic Charge
Positively charged amine groups on modified starch molecules adsorb onto negatively charged cellulosic fiber surfaces through electrostatic attraction. Stock preparation systems dose quaternary ammonium-modified starches at specific addition rates relative to dry fiber mass. Adsorbed starch molecules form hydrogen bonds during sheet drying, which increases dry tensile strength and internal bond strength.
Over-dosing neutralizes the net negative charge of the pulp suspension, which reduces retention aid efficiency and causes wet-end foaming. Continuous charge measurement via streaming current detectors optimizes cationic starch loading addition rates during grade changes.
Internal Strength
Fiber retention and internal bond strength directly govern paperboard burst resistance and lint reduction during printing. Paperboard mills increase starch addition to maintain structural specifications when using high-yield or recycled fiber furnish. Machine speed capability improves when fine particles remain fixed in the forming sheet.