A system for processing a metal substrate comprising: a quenching system comprising: a top nozzle configured to distribute a cooling agent on a top surface of the metal substrate; a bottom nozzle configured to distribute the cooling agent on a bottom surface of the metal substrate, and a flatness-measuring device located a predetermined distance downstream from the quenching system, wherein the predetermined distance is a distance sufficient for the strip temperature to equilibrate, and wherein the flatness-measuring device is configured to: measure a flatness profile of the metal substrate across a width of the metal substrate; and output the measured flatness profile in a flatness signal, and wherein the system further comprises a controller configured to: receive the flatness signal from the flatness-measuring device; compare the measured flatness profile to a predetermined flatness profile; and control the quenching system such that the measured flatness profile matches the predetermined flatness profile, wherein the top nozzle is configured to stop distributing the cooling agent when a strip temperature of the metal substrate is reduced from an initial temperature to an intermediate temperature that is less than the initial temperature, and wherein the bottom nozzle is configured to continue distributing the cooling agent until the strip temperature of the metal substrate is reduced from the initial temperature to a target temperature that is less than the initial temperature and less than the intermediate temperature, characterized by a coolant removal device to be activated for removing residual cooling agent off the top surface of the metal substrate when the top nozzle stops distributing the cooling agent on the metal substrate, wherein the intermediate temperature is from about 120 °C to about 180 °C, wherein the target temperature is from about 60 °C to about 120 °C, and wherein the initial temperature is greater than about 180 °C. a top nozzle configured to distribute a cooling agent on a top surface of the metal substrate; a bottom nozzle configured to distribute the cooling agent on a bottom surface of the metal substrate, and a flatness-measuring device located a predetermined distance downstream from the quenching system, wherein the predetermined distance is a distance sufficient for the strip temperature to equilibrate, and wherein the flatness-measuring device is configured to: measure a flatness profile of the metal substrate across a width of the metal substrate; and output the measured flatness profile in a flatness signal, and wherein the system further comprises a controller configured to: receive the flatness signal from the flatness-measuring device; compare the measured flatness profile to a predetermined flatness profile; and control the quenching system such that the measured flatness profile matches the predetermined flatness profile, wherein the top nozzle is configured to stop distributing the cooling agent when a strip temperature of the metal substrate is reduced from an initial temperature to an intermediate temperature that is less than the initial temperature, and wherein the bottom nozzle is configured to continue distributing the cooling agent until the strip temperature of the metal substrate is reduced from the initial temperature to a target temperature that is less than the initial temperature and less than the intermediate temperature, characterized by a coolant removal device to be activated for removing residual cooling agent off the top surface of the metal substrate when the top nozzle stops distributing the cooling agent on the metal substrate, wherein the intermediate temperature is from about 120 °C to about 180 °C, wherein the target temperature is from about 60 °C to about 120 °C, and wherein the initial temperature is greater than about 180 °C. receive the flatness signal from the flatness-measuring device; compare the measured flatness profile to a predetermined flatness profile; and control the quenching system such that the measured flatness profile matches the predetermined flatness profile, wherein the top nozzle is configured to stop distributing the cooling agent when a strip temperature of the metal substrate is reduced from an initial temperature to an intermediate temperature that is less than the initial temperature, and wherein the bottom nozzle is configured to continue distributing the cooling agent until the strip temperature of the metal substrate is reduced from the initial temperature to a target temperature that is less than the initial temperature and less than the intermediate temperature, characterized by a coolant removal device to be activated for removing residual cooling agent off the top surface of the metal substrate when the top nozzle stops distributing the cooling agent on the metal substrate, wherein the intermediate temperature is from about 120 °C to about 180 °C, wherein the target temperature is from about 60 °C to about 120 °C, and wherein the initial temperature is greater than about 180 °C.