Disclosed is an apparatus (10) for the application of a liquid to viscous medium (42) onto an application surface (53), comprising a port (14) for providing a connection between the apparatus (10) and a supply of said liquid to viscous medium (42) upstream of the apparatus (10), at least two volumetric delivery pumps (23) for metering volumes of said medium, said volumetric delivery pumps (23) being located downstream of said port (14), each volumetric delivery pump (23) being in fluid connection with an application valve (25) of the apparatus (10), located downstream of the volumetric delivery pump (23) for passing a metered volume of the medium (42) from the delivery pump (23) to said application valve (25). It is characteristic that the apparatus (10) comprises a flow meter (13) in fluid connection with said volumetric delivery pumps (23), which flow meter (13) is located upstream of said volumetric delivery pumps (23).