Calibration of paint and varnish properties: Potentialities using X-ray Spectroscopy and Partial Least Squares

This work presents a method for multivariate calibration of the properties of varnishes and paints, combining X-ray Spectroscopy (XRS) with Partial Least Squares (PLS) data treatment. The potential calibrated property for varnishes was density (calibrated values raging from 0.88 to 0.92 g cm− 3 and absolute errors from 0.0014 to 0.055 g cm− 3). For paints, the potential calibrated property was Stormer viscosity (calibrated values ranging from 72 to 89 KU and absolute errors from 0.4 to 8 KU). The information here presented was also promoted by the influence of Compton and Rayleigh effects observed in X-ray spectra. X-ray fluorescence spectra were obtained using an ED- XRF system equipped with a Rh target X-ray tube. The importance of the X-ray scattering region (from 18.00 to 24.00 keV), where Compton and Rayleigh effects occur, were evidenced by the best PLS models and lower error values. With the PLS method and X-ray spectra it was also possible to calibrate the content % (m/m) of two organic elements, C and H. It is important to highlight that the proposed analytical method permitted to save time in the quality control of the studied samples, reducing the generation of residues.