Study of aging in oil paintings by 1D and 2D NMR spectroscopy.

Nuclear magnetic resonance spectroscopy is proposed as an efficient analytical tool in the study of painted artworks. The binding medium from two original oil paintings, dated from the early 20th and the late 17th century, was studied via high-resolution 1D and 2D NMR, establishing the advanced state of hydrolysis and oxidation of the oil paint. Studies of the solvent-extractable component from model samples of various drying oils, raw oil paints, and aged oil paints allowed the definition of several markers based on the integral ratios of various chemical species present in the 1H and 13C NMR spectra. These markers are sensitive to hydrolytic and oxidative processes that reflect the extent of aging in oil paintings. The rapidity, simplicity, and nondestructive nature of the proposed analytical NMR methodology represents a great advantage, since the usually minute sample quantities available from original artwork can be subsequently analyzed further by other analytical techniques, if necessary.