Abstract: An applicator for applying a coating liquid to a moving web of paper carried through an application zone, wherein the applicator has a chamber for receiving the coating liquid and an opening thereto for directing the liquid into an application zone and onto the web, the zone being established between a front wall of the chamber and a doctor blade extending from a rear side of the opening across and against the web, is characterized by a readily removable and replaceable orifice plate on the front wall, which extends toward and closely spaced from the web to define with the web a gap through which coating liquid in the zone flows to form a liquid seal. Because the orifice plate may readily be removed and replaced, orifice plates of different heights may be used with the applicator, so that simply by selecting a particular orifice plate for use, the gap in which the liquid seal is established may be made to have a predetermined size.