Abstract: An apparatus for the application of a flowable medium (2, 2′) from a stock chamber (7, 8) to a surface (6) being moved along the apparatus, and to the use of an apparatus of this type. The stock chamber (7, 8) partly covers the surface (6), with formation of a sealing gap (14) and an exit gap (18). In order to prevent the formation of air bubbles in the medium (2, 2′), it is proposed to divide the stock chamber (7, 8) into a pre-chamber (7) and a main chamber (8). A dividing element (10) which, together with the surface (6), limits a dividing gap (15), is arranged between the chambers. Various shapes of the dividing element are proposed. The apparatus is particularly suitable for the application of a polymer dispersion to the surface (6). A process for operating an apparatus of this type is also described.