Procedure for measuring coating rates

Abstract

The invention concerns a procedure for measurement of the material quantities in coating layers applied upon a base material, by utilizing x-ray radiation. The procedure is particularly suited for use in a paper or cardboard manufacturing process wherein onto a material web in continuous motion are applied by steps one or several coating courses. The radiation source and detector are both placed on one side of the moving web, and the procedure is based on measurement of the fluorescence radiation excited by the primary x-ray radiation obtained from the radiation source in the material underlying the coating layer that is to be measured. The primary and secondary radiation both are thereby compelled to pass through the coating layer under measurement before the arrival of the fluorescence radiation at the detector. The moving web may be equipped with a plurality of consecutive pairs of radiation source and detector, the first pair measuring the fluorescence radiation from the base material before application of the coating layer and the latter measuring the equivalent fluorescence radiation after applying the coating layer, in above-presented manner. It is alternatively possible to use one single radiation source and detector and to measure simultaneously the fluorescence radiation produced both in the coating layer under measurement and in the underlying base material.