A blade is used to cut through a film between the panes of laminated glass in the area of a gap produced in the laminated glass the blade is provided on a holding device and can move along the gap. The holding device includes swiveling carrier on which there is a holding part for the blade with a vertical adjustment capacity. The blade is first placed next to the gap on the top of the top pane of the laminated glass. The vertical alignment of the blade is ascertained with a rule for determining the thickness of the laminated glass. Then the holding device is adjusted by a motor such that the blade falls into the gap. When a sufficient immersion depth of the blade into the gap is ascertained via the rule, the film is cut.