Static electricity may be the cause of malfunctioning of high speed printing presses. At the feeder sheets may stick together with mis-registration and machine stop as a result. Ionising air knives blowing in paper direction to separate the top sheet from the stack with ionised air. The top sheet is now fed into the machine and can be neutralised in open air when passing underneath the bar, mounted on top of the stack. Single or double side neutralisation at the delivery section will ensure a neat stack.