Abstract: A method for producing a sealing seam which joins two film sides. The method includes performing a pre-sealing process and a final sealing process. The pre-sealing process includes heating at least one film side of the two film sides, and, in a heated state of the at least one film side, bringing the two film sides into contact with one another to form a pre-sealing seam which joins the two film sides together. The final sealing process includes supplying the pre-sealing seam at a transport speed to a pressing device which is arranged downstream of the pre-sealing process, and applying a force via the pressing device to at least one film side of the two film sides along the pre-sealing seam substantially perpendicular to the transport direction to transform the pre-sealing seam into a final sealing seam which is substantially impermeable to air.