After disintegration, MFC is typically obtained as a suspension in liquid, usually water. During homogenization, the suspension changes froma lowviscosity to ahigh viscositymedium. Normally a 2 wt% fiber suspension is used for the preparation of MFC. At higher concentrations, the increased viscosity during processing becomes too high, such that the suspension cannot be moved forward by the pumping system. The MFC aqueous suspensions display a gel-like behavior as shown in Fig. 2.