Abstract: A method and apparatus for mixing and dispensing two different polymeric materials which react chemically with one another when combined by supplying each material to a common dispenser where the materials are mixed and dispensed, which method and apparatus is operative to maintain substantially steady state flow pressures of the materials at the inlets to the dispenser when flow is terminated such that upon restarting of the flow, the steady state volumetric ratio of materials is immediately reestablished and maintained. The method and apparatus includes two metering pumps for individually supplying the liquid materials to the dispenser and means for varying the speeds of the pumps in response to changes in temperature of the materials so as to maintain a fixed mass ratio of the materials to the dispenser.