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.
Supercalender
Finishing Machine
Producing high-gloss, smooth paper surfaces for high-quality printing requires a mechanical treatment after the papermaking process. A supercalender is an off-machine stack of alternating hard steel rolls and soft filled rolls that compresses the paper web under high pressure and temperature. This treatment polishes the surface by friction, which generates a highly uniform thickness and gloss.
It differs from standard calenders because the soft rolls deform slightly, which ensures that the paper is polished without crushing its internal fiber structure. This process is commonly used to produce magazine paper and release liners for labels.
Deformation Action
The stack applies both vertical compression and lateral shearing forces to the paper web. As the paper passes through the nip, the soft roll compresses and then expands, which creates a micro-sliding motion against the smooth steel roll. This sliding action polishes the paper surface to improve its gloss and smoothness.
The moisture content of the incoming web must be carefully controlled, as too much moisture leads to blackening of the paper.
Print Quality
Smoother surfaces reduce ink consumption and improve the clarity of fine-screen halftone images. This finish is essential for the high-speed gravure and web offset printing used in commercial publishing.