Abstract: A coating system, a paper machine, and methods of their use are provided.

Abstract: A glue detecting system uses linear filament lamps and photodiodes mounted in the ends of nonreflective tubes to distinguish between diffuse and specular reflections from the surface of a moving article. Sensor photodetectors are positioned directly over the locations where glue beads are intended to be present; reference photodiodes observe the surface where no glue is intended. The spacing between certain photodiodes in the direction of movement of the article may be used to determine the velocity of the article, and the intensity of the reflections is used to determine the presence of glue in the desired areas, and the presence of unwanted glue in other areas; the duration of the specular reflections is used to determine the volume of glue present. An alarm circuit indicates an insufficient amount of glue in the desired areas or the presence of unwanted glue in undesired areas.