When solid and liquid contact, the original solid-liquid interface disappears, forming a new solid-liquid interface. This phenomenon is called wetting. When the pigment filler is wetted with liquid and permeated into the agglomerates and aggregates of the pigment filler, if a small amount of surfactant is added into the liquid, the wetting and infiltration will be easier, which is the wetting effect. The surfactant that makes the pigment filler wet or accelerates the wetting is called wetting agent. This kind of liquid in water-based coating is water.            The main factors affecting the dispersion are the surface properties of pigments and fillers, the types and amounts of wetting dispersants, and the efficiency of dispersion equipment.            The stability or agglomeration of the suspension and dispersion system of pigments and fillers depends on the force, repulsion and attraction between particles. Repulsion is the main factor of stability and attraction is the main factor of agglomeration.