Method for determining adhesive penetration into at least one porous coating material

A method for determining the adhesive penetration into at least one porous coating material which is pressed with at least one carrier plate and at least one adhesive layer, wherein the at least one adhesive layer is arranged on the carrier plate and the at least one porous coating material is arranged on the at least one adhesive layer, wherein the adhesive penetrates or rises into the at least one porous coating material during the pressing process,

• comprising the steps of:
• 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;
• determining adhesive penetration into the porous coating material of said reference samples by means of a mechanical removal of the porous material surface;
• correlating the adhesive penetration determined by mechanical removal with the recorded NIR spectra of said reference samples;
• establishing 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 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 at least one adhesive layer using the at least one NIR measuring head in a wavelength range between 500 nm and 2500 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.