Colloidal Silica Polishing. Colloidal silica polishing a processing method based on the characteristic colloidal phenomenon through the use of a slurry with superfine particles of several 10 to several 100 Å suspended in a pH-controlled processing solution (e.g., alkali solution of pH ∼12). Thin colloidal silica exist between an artificial leather-like soft polisher and the workpiece. Once a shearing force is set to work in a horizontal direction under high pressure, the gelation phenomenon inherent in colloids is induced temporarily, a process known as dilatancy phenomenon. In this mechanism, polishing is accelerated by the mechanical microremoval action of an atomic/molecular order mainly through cohesive and abrasive actions of SiO2 fine particles that are held in the apparently gelated solutions (Figure 6.27) [37].