During Stage I the total volume of the system decreases (because of drying) and this causes the material to shrink. Such a phenomenon takes place until the solid particles form a rigid skeleton . Starting from this point CS Stage II starts. Similar to all the liquid phase sintering processes particle rearrangement takes place, followed by the formation of physical interparticle necks. Note that in UCS Stage I may not occur, in that case the process starts with Stage II. The progressive evaporation of the liquid medium is accompanied by material densification (or by the formation of pores). Stage II can be carried out with (UCS) or without (ICC) an external pressure.