A process for the preparation of a glass container from a glass tube in a glass processing machine, wherein the glass tube comprises a first portion with a first end, a second portion with a second end and a longitudinal axis L tube that passes through the centre of the first and the second end (203,205), wherein the glass processing machine comprises a plurality of processing stations, first and second clamping chucks (206,207) which are adapted and arranged to hold the glass tube while rotating the glass tube around its longitudinal axis L tube and to transport the rotating glass tube from one glass container processing station to the next one, a heating device and a mold matrix, wherein the process comprises the steps of I) heating the glass tube at a defined position between the first portion and the second portion to a temperature above the glass transition temperature while the glass tube is rotating around its longitudinal axis L tube and pulling apart the first portion and the second portion thereby separating the first portion from the second portion and forming a closed bottom at one end of the first portion; II) moving the mold matrix towards the closed bottom and bringing the mold matrix into contact with the closed bottom; wherein, while bringing the mold matrix into contact with the closed bottom in process step II), a distance Y m between the mold matrix and the first clamping chuck is decreased stepwise. wherein the glass tube comprises a first portion with a first end, a second portion with a second end and a longitudinal axis L tube that passes through the centre of the first and the second end (203,205), wherein the glass processing machine comprises a plurality of processing stations, first and second clamping chucks (206,207) which are adapted and arranged to hold the glass tube while rotating the glass tube around its longitudinal axis L tube and to transport the rotating glass tube from one glass container processing station to the next one, a heating device and a mold matrix, wherein the process comprises the steps of I) heating the glass tube at a defined position between the first portion and the second portion to a temperature above the glass transition temperature while the glass tube is rotating around its longitudinal axis L tube and pulling apart the first portion and the second portion thereby separating the first portion from the second portion and forming a closed bottom at one end of the first portion; II) moving the mold matrix towards the closed bottom and bringing the mold matrix into contact with the closed bottom; I) heating the glass tube at a defined position between the first portion and the second portion to a temperature above the glass transition temperature while the glass tube is rotating around its longitudinal axis L tube and pulling apart the first portion and the second portion thereby separating the first portion from the second portion and forming a closed bottom at one end of the first portion; II) moving the mold matrix towards the closed bottom and bringing the mold matrix into contact with the closed bottom; wherein, while bringing the mold matrix into contact with the closed bottom in process step II), a distance Y m between the mold matrix and the first clamping chuck is decreased stepwise.