Gripper cracks happen on coil stamps. Most coil stamps are printed by a press that uses a cylinder with two plates attached to it. The plates are held to the cylinder by means of grippers that hold the plates down at the ends. These plates have small spaces in them that the grippers can hold. Because of the stress that the grippers exert on the plates, cracks can develop where the grippers are located. In general the "gripper cracks" can occur mainly on the stamps immediately to the left and the right of the joint- or seam line.