A method for mounting a printing master on a printing form cylinder includes readying a new print job with a printing-image length by releasing an unwinding spool, activating an unwinding spool drive for moving the printing master a length in circumferential direction of the cylinder on the circumferential surface by drawing the printing master to a rewinding spool and braking the unwinding spool for building tension. A preceding job image start is located on the surface facing the rewinding spool. A control device activates the unwinding spool drive and, before activation, data is produced in the control device regarding the length to be spooled forward, and the spools are fixed, after advancing the printing master a length, for insuring tension. A value is determined for the printing master length to be spooled forward, being at most the printing image length of the preceding print job plus a printing image spacing.