Two liquid components, an isocyanate and a polyol, are placed in holding tanks. They are conditioned to the correct temperatures (approximately 100 degrees Fahrenheit), pressures, and specific gravities. The dispensing unit pumps the correct amounts and ratios of these liquids into the mold during the injection phase of the molding cycle. During the molding process, the unit continuously circulates the isocyanate and the polyol at low pressures to keep them uniformly conditioned.