After each use, remove the cartridge and gently wipe any residual spray from the nozzle with a tissue. Then flush out the sprayer by pressing the nozzle button for a few seconds. Before using again, flush the unit by pressing the nozzle button (you should feel air coming out of the nozzle head). Insert a cartridge into the nozzle and listen for a "click". Spray in a circular fashion about 1 inch away from the paper.