<p>A method for evaluating performance of a plurality of nozzles of a printing head includes repeatedly operating each of the nozzles to print test marks on a surface of a substrate, each of the test marks printed by that nozzle being printed at a different time. At least once during the repeated operation of each of the nozzles, at least some of the test marks are erased from the surface. The test marks that were printed by that nozzle are inspected for a feature that is indicative of the performance of that nozzle.</p>
