Method for determining the quantitative ratio of melamine-formaldehyde resin and urea-formaldehyde resin in at least one paper layer impregnated with a mixture of these resins, wherein the impregnation is carried out in a plant for impregnating at least one paper layer passing through the plant, Comprising the steps - Impregnating of several paper layers with resin mixtures, each with different quantitatively defined ratios of melamine-formaldehyde resin and urea-formaldehyde resin as reference samples; - Recording of at least one NIR spectrum of each of the reference samples 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 1450 nm and 1550 nm; - Correlating the different quantitative ratios of melamine-formaldehyde resin and urea-formaldehyde resin in the reference samples to the recorded NIR spectra of said reference samples; and - Establishing a calibration model for the correlation between the spectral data of the NIR spectra and the associated quantitative ratios of melamine-formaldehyde resin and urea-formaldehyde resin of the reference samples by means of multivariate data analysis; - Impregnating at least one paper layer with a resin mixture of melamine-formaldehyde resin and urea-formaldehyde resin; - Recording at least one NIR spectrum of the impregnated paper 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 1450 nm and 1550 nm; and - Determining the quantitative ratio of melamine-formaldehyde resin and urea-formaldehyde resin in the impregnated paper layer by comparing the NIR spectrum recorded for the impregnated paper layer with the calibration model created. - Impregnating of several paper layers with resin mixtures, each with different quantitatively defined ratios of melamine-formaldehyde resin and urea-formaldehyde resin as reference samples; - Recording of at least one NIR spectrum of each of the reference samples 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 1450 nm and 1550 nm; - Correlating the different quantitative ratios of melamine-formaldehyde resin and urea-formaldehyde resin in the reference samples to the recorded NIR spectra of said reference samples; and - Establishing a calibration model for the correlation between the spectral data of the NIR spectra and the associated quantitative ratios of melamine-formaldehyde resin and urea-formaldehyde resin of the reference samples by means of multivariate data analysis; - Impregnating at least one paper layer with a resin mixture of melamine-formaldehyde resin and urea-formaldehyde resin; - Recording at least one NIR spectrum of the impregnated paper 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 1450 nm and 1550 nm; and - Determining the quantitative ratio of melamine-formaldehyde resin and urea-formaldehyde resin in the impregnated paper layer by comparing the NIR spectrum recorded for the impregnated paper layer with the calibration model created. <EOS>