2. Refining

The aim of this fundamental step in the pulp preparation process is to modify the physical state of the fibers by mechanical means, in order to obtain the qualities required for processing and use of the paper produced. If this phase were omitted, paper produced from unrefined fibers would never (with the exception of blotting paper) have the desired physical characteristics.

Refining has three main effects on the fibres, with different consequences on the manufacturing process and on the properties of the paper:

• swelling or hydration of fibers, resulting in water penetration and increased suppleness;

• fibrillation or the creation of fibrils and fine elements that increase the possibility of contact between fibers and therefore of bonding;

• cutting,...