Abstract: A recirculating coating liquid supply system for continuous delivery of a supply of coating liquid to a coating apparatus includes a holding tank carrying coating liquid mixture, a main feed line having an intake at the holding tank and a discharge at an applicator trough associated with the coating apparatus. A branch of the main feed line discharges into the holding tank. The system also includes a return feed line having an intake at the applicator trough and a discharge at the holding tank. Pumps are associated with both the main feed line and the return line and a viscometer is connected to measure the viscosity of the coating liquid mixture flowing through the main feed line. Viscosity adjustments are made by infusing measured quantities of coating liquid base or coating liquid thinner into the main feed line.