Method for determining the adhesive penetration in the form of the penetration height of the adhesive into at least one porous coating material which is pressed with at least one carrier plate and at least one adhesive layer arranged on the carrier plate, wherein the adhesive penetrates or rises into the at least one porous coating material during the pressing process, comprising the steps - Recording at least one NIR spectrum of several reference samples, each having different values for adhesive penetration into a porous coating material, using at least one NIR measuring head in a wavelength range between 500 nm and 2500 nm, preferably between 700 nm and 2000 nm, particularly preferably between 900 nm and 1700 nm, and especially advantageously between 1000 nm and 1300 nm and/or between 1400 nm and 1550 nm; the reference samples being identical to the sample to be measured; - Determining of adhesive penetration into the porous coating material of said reference samples by means of a mechanical removal of the porous material surface; - Correlating of the adhesive penetration determined by mechanical removal with the recorded NIR spectra of said reference samples; and - Establishing of a calibration model for the relationship between the spectral data of the NIR spectra and the corresponding adhesive penetrations of the reference samples using multivariate data analysis; - Pressing of at least one porous coating material with at least one carrier plate and at least one adhesive layer arranged on the carrier plate, - Recording at least one NIR spectrum of the porous coating material pressed with the carrier plate and the adhesive layer using the at least one NIR measuring head in a wavelength range between 500 nm and 2500 nm, preferably between 700 nm and 2000 nm, in particular preferably between 900 nm and 1700 nm and especially advantageously between 1000 nm and 1300 nm and/or between 1400 nm and 1550 nm; and - Determining the adhesive penetration into the at least one porous coating material by comparing the NIR spectrum recorded for the porous coating material with the calibration model created. - Recording at least one NIR spectrum of several reference samples, each having different values for adhesive penetration into a porous coating material, using at least one NIR measuring head in a wavelength range between 500 nm and 2500 nm, preferably between 700 nm and 2000 nm, particularly preferably between 900 nm and 1700 nm, and especially advantageously between 1000 nm and 1300 nm and/or between 1400 nm and 1550 nm; the reference samples being identical to the sample to be measured; - Determining of adhesive penetration into the porous coating material of said reference samples by means of a mechanical removal of the porous material surface; - Correlating of the adhesive penetration determined by mechanical removal with the recorded NIR spectra of said reference samples; and - Establishing of a calibration model for the relationship between the spectral data of the NIR spectra and the corresponding adhesive penetrations of the reference samples using multivariate data analysis; - Pressing of at least one porous coating material with at least one carrier plate and at least one adhesive layer arranged on the carrier plate, - Recording at least one NIR spectrum of the porous coating material pressed with the carrier plate and the adhesive layer using the at least one NIR measuring head in a wavelength range between 500 nm and 2500 nm, preferably between 700 nm and 2000 nm, in particular preferably between 900 nm and 1700 nm and especially advantageously between 1000 nm and 1300 nm and/or between 1400 nm and 1550 nm; and - Determining the adhesive penetration into the at least one porous coating material by comparing the NIR spectrum recorded for the porous coating material with the calibration model created.