an apparatus for transforming plastic preforms into containers , includes at least one blow mould which forms a cavity , inside which the plastic preforms can be transformed into containers . the apparatus includes an opening and closing mechanism for opening and closing the blow mould , and a cleaning device for cleaning regions of the blow mould . the cleaning device includes at least a first cleaning element for cleaning an inner wall of the blow mould , which cleaning element is arranged at least at times outside the blow mould .