Abstract: An ink density closed loop control system for an ink ribbon of an impact printer having a reservoir roller formed of an ink absorbent material with at least one or more channels within the reservoir roller fluidly connected to a pump and ink supply. A transfer roller can contact the reservoir roller for imparting ink to the ink ribbon. A sensor senses the relative amount of ink on the print ribbon and an electrical drive responsive to the sensor drives the pump for a flow of ink to the one or more channels. The sensor can sense ink on different segments of the ribbon and, with two or more channels in the reservoir roller can distribute ink to two or more segments of the reservoir roller depending upon the ink sensed at a particular segment of the ribbon. A further enhancement of this invention provides a multi-viscosity ink to compensate for changes in ambient temperature conditions.