How Paper Is Coated Calendered and Finished
Inline blade coating and soft-nip calendering establish surface uniformity, while targeted finishing passes balance visual embellishment against repulpability.
Beveled Blade
Metering Element
Liquid coatings applied to a moving web of paper or paperboard must be smoothed and controlled to ensure an even distribution across the entire surface. A beveled blade is a steel strip with a pre-ground angled edge that rides against the wet coating layer. This tool uses a specific angle of attack to shave away excess coating rather than bending under the hydrodynamic pressure of the liquid.
It sits at a fixed angle to the backing roll to maintain a precise gap for the passage of the slurry. The uniform contact area prevents streaks and maintains a consistent coat weight across varying press speeds.
Angle Integrity
The wear behavior of the steel determines the lifespan of the tool and the quality of the finished sheet. As the blade contacts the moving web, the abrasive pigments in the coating clay gradually wear down the steel to create a flat land area. This land area alters the hydrodynamic pressure beneath the blade, which reduces the coat weight and degrades the surface profile.
Press operators must adjust the blade angle or replace the steel strip to counteract this wear. Modern coating lines use ceramic tips to extend the period of stable operation.
Blade Geometry
Steeper angles of the bevel produce thinner coatings with higher precision on smooth base papers, because the sharper edge limits hydrodynamic lift.