According to one example, there is provided a method of controlling a printing system. The method comprises: obtaining a print job to print on a substrate; obtaining a value of a factor material to an undesirable condition occurring; determining a quantity of printing fluid to be deposited on a substrate when printing a portion of the print job; determining, based on the obtained value and the determined quantity of printing fluid to be deposited, whether the undesirable condition is likely to occur whilst printing the portion of the print job; and temporarily reducing the throughput of the printing system whilst printing the portion of the print job where it is determined that the undesirable condition is likely to occur whilst printing the portion of the print job.