Abstract: A method and a processor having infrared sensed chemical replenishing system for processing photosensitive material. The processor includes a replenishing circuitry having a power supply; a pulsed infrared sensor electrically connected to the power supply for measuring the width of photosensitive materials; a pulse generator circuit for generating a pulse width and repetition rate to the infrared sensor means; and a summing circuit for producing a summation of all latched input elements transmitted from the sensor. The replenishing circuit also includes a replenishment calibration timing circuit for producing a replenishment command signal following a successive time interval equal to the time required for the processor drive to turn one revolution, and a control circuitry for controlling the chemical flow of the replenishment system.