Spectral characterization for the evaluation of a protective coating on dolomite by visible and near infrared spectroscopy

Calcareous heritage stones are essential to the European cultural heritage but vulnerable to weathering that compromises their structural and aesthetic integrity. Graphene oxide (GO) emerges a promising protective coating, enhancing resistance to climatic aggressions while preserving the stone’s appearance and reducing restoration costs. To ensure effective application and to monitor durability, rapid and consistent on-site analytical methods are needed. This study evaluates infrared spectroscopy as a non-destructive and reliable tool for the characterization and quantification of GO coatings applied to dolomite stones coming from two different Spanish quarries. Using a partial least squares regression, spectral data enabled accurate assessment of the coating presence, concentration (which was tested in the range from 0 to 16.5 µg·cm⁻²), and uniformity. This work establishes vibrational spectroscopy as a powerful in situ technique for monitoring protective coatings on heritage stones, providing a measurable and reliable framework to safeguard cultural assets against environmental degradation.