METHOD FOR DETERMINING THE COATING QUANTITY ON A MATERIAL WEB

This invention relates to a method for determining the quantity of a coating applied to a material web, in particular a fibrous web, with which radiation is directed onto the material web coated with the coating and the radiation interacts at least with the coating, and with which at least a fraction of the radiation that has interacted with the coating is detected in order to determine, on the basis of at least one measurement signal produced by way of the detected radiation, the quantity of the coating on and if necessary in the material web. The radiation, after its interaction, is detected in various frequency bands in order to produce a specific measurement signal for each frequency band, wherein the frequency bands include at least one frequency common to all frequency bands and the frequency bands are selected such that, with any given quantity of the applied coating, at least one of the specific measurement signals varies more with the structure of the applied coating than another of the specific measurement signals and the specific measurement signals of the various frequency bands are mathematically linked with each other to determine the quantity of the coating.