Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)This article reports an analytical study of modifications occurring on surfaces coated by 17 varnishes and 10 paints. The surface films were submitted to accelerated laboratory tests and atmospheric environmental exposures. Digital image processing, energy dispersive X-ray fluorescence spectrometry (ED-XRF), and principal component analysis (PCA) were applied. Digitalized images were obtained using a conventional scanner and converted into gray color scale histograms. The data were organized into a matri and analyzed with PCA. This method permits the classification of weatherproofing products according to their performance in the tests, avoiding subjective interpretations. ED-XRF spectra combined with PCA were also efficient for evaluating deterioration processes of varnishes and paints, confirming the results from digitized images.64445455Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [04/02094-3]