FT-NIR spectroscopy for non-invasive identification of natural polymers and resins in easel paintings

Abstract

In the present study, the analytical strengths and limitations of near-infrared (NIR) spectroscopy to non-invasively characterize organic components in painting materials have been investigated. In spite of the increased amount of information available today from advanced modern analytical instrumentations dedicated to cultural heritage, the non-invasive identification of materials belonging to the wide class of organic compounds historically used in paintings is still a challenging task. Near-infrared spectroscopy offers several attractive features that make this technique particularly suitable to this purpose. In fact, it is non-invasive, allows for non-contact measurements in reflectance mode, gives molecular information on complex macromolecules, and can be performed on-site by means of portable devices. First-derivative transformation of reflectance spectroscopic data has been applied to provide a simple and fast way to deduce more information from NIR spectra. This approach has allowed spectral features to be identified that can be useful to distinguish different compounds belonging to the classes of lipids, proteins, and resins. To this purpose, at first, a spectral database of pure standard has been collected. Our analytical approach was then successfully validated on pictorial models reproducing the typical stratigraphy of an easel painting. As final step, the study of a real painting has been attempted and a drying oil, animal glue, and a terpenic natural resin, as well as an earth pigment were clearly identified, as cross-validated by GC-MS analysis.

MOLAB®meets Persia: Non-invasive study of a sixteenth-century illuminated manuscript

“…4A) in UV-Vis-NIR-SWIR spectra (Fig. 4A) (Vagnini et al, 2009) and by the CH combination bands at 2850, 2930, and 2955 cm −1 in the mid-FTIR spectra. The evidence is most clear on fol.…”

Visible and infrared imaging spectroscopy of paintings and improved reflectography

“…These features are often related to functional groups like hydroxyl (−OH) and carbonate (−CO 3 ) [7]. Absorption features from organic materials like the paint binding media, including the amide groups of proteins and lipid bands of oils and waxes, can also be observed [14] and even used to map their spatial distribution [15,16].…”

“…However, to discriminate between pigments having sharp transition edges, such as red and yellow semiconductor pigments, a resolution of <5 nm may be necessary. In the SWIR region, the required resolution should be <10 nm in order to resolve the narrow vibrational bands associated with some binding media [14][15][16]. X-ray fluorescence, in contrast, provides information on the elemental composition of materials and allows one to infer the possible colorants present [17].…”

Towards enhancing sustainable reuse of pre-treated drill cuttings for construction purposes by near-infrared analysis: A review

“…For instance, vis-NIR spectroscopy has found application in the petrochemical industries for gasoline classification (Balabin and Safieva, 2008) and identification of polymers and resins in painting materials (Vagnini et al, 2009). Vis-NIR diffuses reflectance spectroscopy (DRS) (350-2,500 nm) and vis-NIR spectroscopy (909-2000 nm) in transmittance mode has been respectively used to determine the amount of hydrocarbons (toluene, isooctane and n-hexane) sorbed on chrome shavings and the adsorption capacity of the chrome shavings during the remediation of hydrocarbonpolluted waters.…”