A method and apparatus for incorporating feature substances into a still moist but already sufficiently consolidated paper web provides for directing a feature substance suspension onto the surface of the paper web as a laminar jet with low jet pressure. A special pressure control circuit ensures that the jet pressure is always constant regardless of the number of parallel feature substance suspension jets directed onto the paper web. This makes it possible to incorporate a great variety of line codings in paper under the same process conditions without any visible changes in fiber structure occurring in the paper.