Provided is an apparatus for forming plastic preforms into plastic containers, having a blow mould which forms a cavity within which the plastic preforms can be expanded to form the plastic containers, and having an application device which is suitable and intended for acting upon the plastic preforms with a flowable medium in order to expand them, which is suitable and intended for acting upon the plastic preforms with a flowable medium in order to expand them, wherein the application device is placed against a mouth area of the plastic preforms in order to act upon these with the flowable medium. The application device forms at least one first flow channel for the flowable medium, which guides and/or directs at least a portion of the flowable medium to an inner wall of the mouth area in order to temper and, in particular, cool this inner wall.