Paper finishing

The characteristics, appearance and properties of paper and board are supplemented and enhanced by their final treatments. These may be simple processes where the reel is slit into a number of more narrow reels or cut into sheets or more complicated processes such as coating or super-calendering.

Coating improves the opacity, lightness, surface smoothness, lustre and colour-absorption ability of paper. It meets exacting quality demands regarding surface smoothness. Coating means that a layer is applied to the paper, either directly in the papermaking machine or separately. Varieties of coated paper range from pigmented to cast-coated. The coat consists of a mix of pigments, extenders such as china clay and chalk, and binders such as starch or latex. In addition, various chemicals are added to give the paper the desired characteristics.

For even smoother paper surface, super-calendering is required. This is done primarily for magazines and coated papers. The paper passes through rollers, which are alternately hard and soft. Through a combination of heat, pressure and friction, the paper acquires a high lustre surface. The paper becomes somewhat compressed during the process and is therefore thinner than its matt finished equivalent.

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