Aluminum stearate is a white metallic soap made by the precipitation of stearic acid to produce a waxy powder. It repels water and dissolves in hot oil or mineral spirits. This compound is an effective thickening and gelling agent. It is used in commercial manufacturing to thicken varnish and prevent the separation of pigment and oil in paint.
When used in paint, this metal soap helps keep pigment particles from settling by coating their surfaces. Its stearic properties prevent the particles from sticking together and forming clumps. When it is present, less oil is needed to keep the pigment wet. Paint that contains this compound does not separate as much over long periods.
This substance is insoluble in ether, alcohol and water but dissolves in vegetable oil. When used in high enough concentration, it gels upon cooling. Manufacturers put this compound in paint used for construction as well as in artists' paints.