In order to seal the corner joint of an elastoplastic tape placed as a spacer on a glass pane, a film strip is pressed with a first portion of its length against the first leg section of the spacer and the protruding portion of the film strip is wrapped around the corner and pressed against the second leg section. For the purpose of automating this process, the film strip is severed mechanically from an automatically supplied film tape and held via a transfer apparatus which thereafter presses the film strip with the first portion of its length against the first leg section. The portion of the film strip protruding freely over the corner is wrapped around the corner via a pressure carriage and pressed by tautening against the second leg section of the spacer.