Abstract: An ink fountain assembly for use in duplicating machines, such as rotary offset lithographic machines. A fountain trough is defined by an elongated blade extending along one side of the trough and an ink fountain roller extending along the other side of the trough. A fixed wall defines one end of the trough for flush abutment against adjacent ends of the blade and the roller to prevent ink leakage therethrough. An adjustable wall defines an opposite end of the fountain trough and is releasably secured against the top of the blade to provide a seal therewith. The adjustable wall is movable relative to the blade to bring the adjustable wall into flush abutment against the opposite end of the ink fountain roller to provide a seal therewith and prevent ink leakage therebetween.