A method and apparatus is disclosed for operating an ink jet print head 14 of the type having an air chamber 64 to which a stream of air is delivered and an ink chamber 32. A valve 48 interrupts the flow of air to the air chamber 64 from time to time, such as after each copy of a print is printed by the print head. This reduces the air pressure within the air chamber 64 and permits ink from ink chamber 32 to enter the air chamber 64 and replenish ink within the air chamber. The ink pressure is increased while the air pressure is reduced. This reduces the time required to replenish the ink. With the ink in the air chamber maintained at a consistent quantity and shape, the convergence of ink drops on printing medium is enhanced.