A method for manufacturing a glass assembly comprises the steps: lowering of a dip pipe that gas may flow through vertically to the surface of a glass melt; determining when the surface of the glass melt is encountered by the dip pipe end showing towards the glass melt by detecting an increase of the gas pressure found inside the dip pipe; continued lowering of the dip pipe until a predetermined depth of entry of the dip pipe end showing towards the glass melt is reached; obtaining a predetermined pressure inside the dip pipe while the dip pipe first stays at the given immersion depth for the given duration and after the predetermined duration is completed, is lifted with a given speed vertically to the surface of the glass melt, thus creating a gas bubble in the glass melt whose walls are attached to the end of the dip pipe; continued lifting of the dip pipe vertically to the surface of the glass melt until the gas bubble is separated from the glass melt, with the wall of the gas bubble remaining at the dip pipe end as a closing film; and setting, especially controlling and/or adjusting of the pressure inside the dip pipe based on the geometry of the film closing the end of the dip pipe as determined by an image capturing device.