A liquid film as applied to a transfer drum or planar surface by the textural force of a member in a trough which contacts one wall of the trough to prevent entrainment of air into the body by the member, e.g. a roller, while a wiper or the like engages the surface to prevent entrainment of air by the...http://www.google.de/patents/US4538541?utm_source=gb-gplus-sharePatent US4538541 - Method of and apparatus for applying a uniform layer of liquid to a surface
