A system for controlling one or more properties of a sheet of material to be manufactured on a sheet-making machine, the system comprising: a plurality of actuators distributed in a cross-machine direction of the sheet-making machine, each actuator having an actuator response configured to vary in response to (i) a first control action that affects a magnitude of the actuator response of that actuator and (ii) a second control action that affects a cross-directional shape of the actuator response of that actuator, each actuator controllable to vary the one or more properties of the sheet by varying both the magnitude and the cross-directional shape of the actuator response of that actuator; at least one scanner operable to measure the one or more properties of the sheet; and a controller in communication with the at least one scanner and operable to calculate the first and second control actions for each actuator and to implement the first and second control actions at each actuator such that the actuators co-operate to adjust the one or more properties of the sheet to one or more desired targets, wherein each actuator comprises a steam actuator, characterized in that each steam actuator has an outlet chamber for releasing steam to the sheet and a mechanism for changing a cross-directional shape of the steam actuator response comprising: at least one baffle plate that is movable to control a cross-directional position and dimensions of the outlet chamber; or a screen plate with openings covering the outlet chamber and at least one movable plate, wherein movement of the at least one movable plate with respect to the screen plate acts to fully or partially obstruct the openings in the screen plate; or at least one air jet associated with the outlet chamber that is dischargeable to control the shape of the steam flow. a plurality of actuators distributed in a cross-machine direction of the sheet-making machine, each actuator having an actuator response configured to vary in response to (i) a first control action that affects a magnitude of the actuator response of that actuator and (ii) a second control action that affects a cross-directional shape of the actuator response of that actuator, each actuator controllable to vary the one or more properties of the sheet by varying both the magnitude and the cross-directional shape of the actuator response of that actuator; at least one scanner operable to measure the one or more properties of the sheet; and a controller in communication with the at least one scanner and operable to calculate the first and second control actions for each actuator and to implement the first and second control actions at each actuator such that the actuators co-operate to adjust the one or more properties of the sheet to one or more desired targets, wherein each actuator comprises a steam actuator, characterized in that each steam actuator has an outlet chamber for releasing steam to the sheet and a mechanism for changing a cross-directional shape of the steam actuator response comprising: at least one baffle plate that is movable to control a cross-directional position and dimensions of the outlet chamber; or a screen plate with openings covering the outlet chamber and at least one movable plate, wherein movement of the at least one movable plate with respect to the screen plate acts to fully or partially obstruct the openings in the screen plate; or at least one air jet associated with the outlet chamber that is dischargeable to control the shape of the steam flow. at least one baffle plate that is movable to control a cross-directional position and dimensions of the outlet chamber; or a screen plate with openings covering the outlet chamber and at least one movable plate, wherein movement of the at least one movable plate with respect to the screen plate acts to fully or partially obstruct the openings in the screen plate; or at least one air jet associated with the outlet chamber that is dischargeable to control the shape of the steam flow.