A printing device is provided, wherein the printing device includes a printing fluid reservoir configured to hold a volume of a printing fluid, a print head assembly configured to transfer the printing fluid to a printing medium, a conduit fluidically connecting the printing fluid reservoir and the print head assembly, and a printing fluid detector. The printing fluid detector includes first and second electrodes configured to be in contact with the printing fluid, and is configured to distinguish printing fluid from printing fluid froth by taking an impedance measurement across the first and second electrodes and comparing the impedance measurement to a froth threshold impedance value that is calibrated to a measured printing fluid temperature.