A coating unit is located after a sheet-fed digital printer on a manufacturing line. As a response to a workpiece entering the coating unit from the printer, coating substance is dosed onto a plate cylinder, and said plate cylinder is rotated to transfer said coating substance onto the workpiece, which is then transferred further on the manufacturing line. As a response to a first time limit expiring after transferring the workpiece further without a subsequent workpiece entering the coating unit, the rotation of the plate cylinder is stopped.