Pigment Dispersion
The replacement of the moisture and air on the surface of the pigment by the solvent (paint) is called wetting. Wetting of solvent-based paints is not a problem because the surface tension of the solvent (paint) is generally always lower than that of the pigment. But wetting requires a process, especially since the pigment is an aggregate, and the solvent needs to flow into the voids of the pigment. When the solvent viscosity is low, the speed of wetting can be very fast. Pay attention to the order of adding the pigment and solvent, add the solvent first and then add the pigment. In water-based paints, due to the high surface tension of water, it is difficult to wet organic pigments, and a wetting agent needs to be added to reduce the surface tension of water.
