Single Sided Lamination Curl against the Flatness Filling Lines Need
Single-sided lamination curl is controlled by balancing nip heat, reverse dampening, decurling bar tension, and conditioning board to filling line humidity.
Board Moisture Balance
Equilibrium State
Cellulose fibres within paperboard hold a specific percentage of water molecules relative to the humidity of the surrounding air. Board moisture balance acts as a control mechanism that stabilizes the physical dimensions of the sheet for print registration. Fluctuations in relative humidity force these fibres to absorb or release water until a new state of rest occurs.
Accurate maintenance of this property prevents curl and ensures consistent performance during high speed converting operations.
Internal Tolerance
Mills adjust the drying sequence to reach a target range that matches the environment of the intended finishing facility. Variations beyond a narrow threshold cause the substrate to warp because the surface tension changes across the width of the roll. Paperboard that remains too dry becomes brittle and cracks under mechanical stress while excess humidity softens the sheet and degrades runnability.
Pressroom operators monitor the humidity of their storage area to maintain the state established at the factory.
Production Outcome
Achieving an ideal condition allows the ink to set properly without distortion of the printed image. Proper hydration levels support the structural integrity of the fibres during the scoring and folding processes. Excessive water uptake softens the cellulose matrix and leads to poor die cutting results.
Consistent levels across the entire surface provide the stability required for precision mechanical processing.