Abstract:
The present invention is related to a method for marking of fibrous products, in particular fibrous cementitious products, using luminescent materials by introduction of said luminescent materials in the fibrous product. The invention is furhter related to methods of detecting the mark by admission of/introduction of energy to the fibrous product and inspection by the human eye or by a preferably automated spectroscopic or spectrometric technique, that capture (specific wavelengths of) the emitted light.