The coating of different substrates is an important part of many industrial manufacturing processes. The fluids used in these processes have very different rheological properties. They are coated to solid surfaces with high substrate velocities by dipping, spraying, casting or by the use of knives, blades and rollers. The field of flow between two rotating rollers is influenced by the free surfaces of the fluid and the contact point between the three phases, solid roller, coating fluid, and the surrounding gas. Viscous, inertial, gravitational and capillary forces control the velocity field between the rollers. Stable fluid coatings that satisfy the increasingly stringent demands on the quality of their surface structure have to be created within certain limits of the forces occurring. In order to predict these limits, the flow fields have to be completely calculated. Therefore all three conservation equations and an additional equation for the position of the free surfaces are solved with consideration of the constitutive equations and possible wall slip effects of the coating fluids.