A working device (1) to be used on blanks running essentially in a planar manner within a folding and gluing machine, with the outer printable surface originally oriented downwards. First turning device (10) turns over each blank so as to position its outer surface on the top. A transport device (20) moves each blank with the outer surface on the top. An action device (30) implements at least one of printing the outer surface of each blank on the one hand and monitoring the outer surface of each blank on the other hand, while the outer surface is facing up. A second turning device (40) turns over each blank again in order to reposition its outer surface downward.