Formation of clusters of pigment particles in a fluid medium that may occur after dispersion. The
condition usually is reversible, and the particle clusters can be broken up by applying relatively
weak mechanical forces or by a change in the physical forces at the interface between the liquid
and the solid dispersed particles. Flocculation is often visible as a “Jack Frost” pattern in a
flowout of a dispersion; microscopically, it appears as a lacework or reticulum of loosely clustered particles. It results in more rapid settling although it is usually soft, shows loss of color strength and poor dispersion. Surface-active agents are often useful in reducing the extent of flocculation and hence the yield value.
